Dual-Input Linear Charger, Smart Power Selector
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
General Description
The MAX8934G dual-input Li+/Li-Poly linear battery charger with Smart Power SelectorK safely charges a single
Li+/Li-Poly cell in accordance with JEITA* recommendations. The MAX8934G monitors the battery temperature
(TBATT) while charging, and automatically adjusts the
fast-charge current and charge termination voltage as the
battery temperature varies. The MAX8934G also monitors
the battery temperature while the battery is discharging,
and provides a warning flag (OT) to the system in the
event that the battery is over temperature. Safety region
2 is supported (see Figure 6 for details). An ultra-low IQ,
always-on LDO provides an additional 3.3V supply for
system power.
The MAX8934G operates with either separate inputs
for USB and AC adapter power, or from a single input
that accepts both. All power switches for charging and
switching the load between battery and external power
are included on-chip. No external MOSFETs are required.
The MAX8934G features a Smart Power Selector to make
the best use of limited USB or adapter power. Input current limit and battery charge current limit are independently set. Input power not used by the system charges
the battery. Charge current limit and DC current limit can
be set up to 1.5A and 2A, respectively, while USB input
current can be set to 100mA or 500mA. Automatic input
selection switches the system load from battery to external
power.
Features
S Li+ Charger with Smart Power Selector, No
External MOSFETs Needed
S Monitors Battery Temperature and Adjusts Charge
Current and Termination Voltage Automatically
per JEITA Recommendations
S OT Flags System of a Hot Battery During
Discharge
S Ultra-Low IQ, Always-On 3.3V LDO
S Common or Separate USB and Adapter Inputs
S Automatic Adapter/USB/Battery Switchover
S Load Peaks in Excess of Adapter Rating are
Supported by Battery
S Input OVP to 16V (DC) and 9V (USB)
S 40mI SYS-to-BATT Switch
S Thermal Regulation Prevents Overheating
S 4.35V SYS Regulation Voltage
Ordering Information
PART
MAX8934GETI+
*JEITA (Japan Electronics and Information Technology
Industries Association) Standard, A Guide to the Safe Use of
Secondary Lithium Ion Batteries on Notebook–Type Personal
Computers, April 20, 2007.
28 Thin QFN-EP**
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
LDO
3.3V ALWAYS-ON
LINEAR
REGULATOR
AC
ADAPTER
DC
SYS
Q1
CHARGE
CURRENT
Applications
PDAs, Palmtop, and Wireless Handhelds
Portable Media, MP3 Players, and PNDs
Digital Still Cameras and Digital Video Cameras
Handheld Game Systems
PIN-PACKAGE
**EP = Exposed pad.
The MAX8934G provides a SYS output voltage of 4.35V.
Other features include overvoltage protection (OVP),
open-drain charge status and fault outputs, power-OK
monitors, charge timers, and a battery thermistor monitor. Additionally, on-chip thermal limiting reduces the
battery charge-rate to prevent charger overheating.
The MAX8934G is available in a 28-pin, 4mm x 4mm,
TQFN package.
TEMP RANGE
-40NC to +85NC
LOAD
CURRENT
SYSTEM
LOAD
Q3
USB
USB Q2
CHARGE
AND
SYS LOAD
SWITCH
BATT
BATTERY
GND
MAX8934G
Smart Power Selector is a trademark of Maxim Integrated
Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-5296; Rev 0; 6/10
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
ABSOLUTE MAXIMUM RATINGS
DC, PEN1 to GND..................................................-0.3V to +16V
USB to GND.............................................................-0.3V to +9V
VL to GND................................................................-0.3V to +4V
LDO to GND.......... -0.3V to the lower of +4V and (VSYS + 0.3V)
THMEN, THMSW to GND...................... -0.3V to +(VLDO + 0.3V)
THM to GND........................................-0.3V to (VTHMSW + 0.3V)
PSET, ISET, CT to GND................................ -0.3V to (VL + 0.3V)
BATT, SYS, CEN, CHG, OT, DOK,
UOK, FLT, DONE, USUS, PEN2 to GND..............-0.3V to +6V
EP (Exposed Pad) to GND....................................-0.3V to +0.3V
DC Continuous Current (total in two pins)..................... 2.4ARMS
SYS Continuous Current (total in two pins).................... 2.4ARMS
USB Continuous Current (total in two pins)................... 2.0ARMS
BATT Continuous Current (total in two pins).................. 2.4ARMS
LDO Continuous Current.............................................. 50mARMS
LDO Short-Circuit Duration.......................................... Continuous
Continuous Power Dissipation (TA = +70NC)
Single-Layer Board
(derate 20.8mW/NC above +70NC).......................1666.7mW
Multilayer Board
(derate 28.6mW/NC above +70NC).......................2285.7mW
Operating Temperature Range........................... -40NC to +85NC
Junction Temperature....................................... -40NC to +125NC
Storage Temperature........................................ -65NC to +150NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK,
UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
6.6
V
DC-to-SYS PREREGULATOR
DC Operating Voltage Range
4.1
DC Withstand Voltage
VBATT = VSYS = 0V
14
V
DC Undervoltage Threshold
When V DOK goes low, VDC rising, 500mV hysteresis
3.95
4.0
4.05
V
DC Overvoltage Threshold
When V DOK goes high, VDC rising, 360mV hysteresis
6.8
V
DC Operating Supply Current
6.9
7.0
ISYS = IBATT = 0mA, V CEN = 0V
1
2
ISYS = IBATT = 0mA, V CEN = 5V
0.8
1.5
mA
DC Suspend Current
VDC = V CEN = VUSUS = 5V, VPEN1 = 0V
195
340
FA
DC-to-SYS On-Resistance
ISYS = 400mA, V CEN = 5V
0.2
0.35
I
DC to BATT Dropout Voltage
When SYS regulation and charging stops, VDC falling,
150mV hysteresis
10
50
90
mV
DC Current Limit
VDC = 5V, VSYS = 4V,
TA = +25NC
RPSET = 1.5kI
1800
2000
2200
RPSET = 3kI
900
1000
1100
RPSET = 6.3kI
450
475
500
VPEN1 = 0V, VPEN2 = 5V
(500mA USB mode)
450
475
500
VPEN1 = VPEN2 = 0V
(100mA USB mode)
80
95
100
PSET Resistance Range
SYS Regulation Voltage
1.5
VDC = 6V, ISYS = 1mA to 1.75A, V CEN = 5V
Connecting DC with USB not present
4.29
6.3
4.35
4.4
mA
kI
V
1.5
ms
Connecting DC with USB present
50
Fs
Thermal-Limit Temperature
Die temperature at when the charging current and input
current limits are reduced
100
NC
Thermal-Limit Gain
ISYS reduction with die temperature (above +100NC)
VL Voltage
IVL = 0 to 5mA, USB = unconnected
Input Current Soft-Start Time
2 5
3
3.3
%/C
3.6
V
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK,
UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
6.6
V
8
V
USB-TO-SYS PREREGULATOR
USB Operating Voltage Range
4.1
USB Withstand Voltage
VBATT = VSYS = 0V
USB Undervoltage Threshold
When V UOK goes low, VUSB rising, 500mV hysteresis
3.95
4.0
4.05
V
USB Overvoltage Threshold
When V UOK goes high, VUSB rising, 360mV hysteresis
6.8
6.9
7.0
V
1
2
ISYS = IBATT = 0mA, V CEN = 5V, VPEN2 = 0V
0.9
1.5
USB Suspend Current
DC = unconnected, VUSB = V CEN = VUSUS = 5V
190
340
FA
USB to SYS On-Resistance
DC unconnected, VUSB = V CEN = 5V, ISYS = 400mA
0.22
0.33
I
USB-to-BATT Dropout Voltage
When SYS regulation and charging stops, VUSB falling,
150mV hysteresis
10
50
90
mV
USB Current Limit
(See Table 2)
DC unconnected,
VUSB = 5V, TA = +25NC
VPEN1 = 0V, VPEN2 = 5V
450
475
500
VPEN1 = VPEN2 = 0V
80
95
100
SYS Regulation Voltage
DC unconnected, VUSB = 6V, VPEN2 = 5V, ISYS = 1mA
to 400mA, VCEN = 5V
4.29
4.35
4.4
Input Limiter Soft-Start Time
Input current ramp time
50
Fs
Thermal-Limit Temperature
Die temperature at when the charging current and input
current limits are reduced
100
NC
Thermal-Limit Gain
ISYS reduction with die temperature (above +100NC)
VL Voltage
DC unconnected, VUSB = 5V, IVL = 0 to 5mA
USB Operating Supply Current
ISYS = IBATT = 0mA, V CEN = VPEN2 = 0V
5
3
3.3
mA
mA
V
%/NC
3.6
V
LDO LINEAR REGULATOR
LDO Output Voltage
DC unconnected, VUSB = 5V, ILDO = 0mA
3.234
3.3
3.366
VDC = 5V, USB unconnected, ILDO = 0mA
3.234
3.3
3.366
DC and USB unconnected, VBATT = 4V, ILDO = 0mA
3.234
3.3
3.366
V
ILDO = 0 to 30mA
0.003
BATT-to-SYS On-Resistance
VDC = 0V, VBATT = 4.2V, ISYS = 1A
0.04
0.08
I
BATT-to-SYS Reverse
Regulation Voltage
VPEN1 = VPEN2 = 0V, ISYS = 200mA
50
75
105
mV
TA = +25NC, VTHM_T2 < VTHM <
VTHM_T3
4.175
4.2
4.225
TA = 0NC to +85NC, VTHM_T2 <
VTHM < VTHM_T3
4.158
4.2
4.242
TA = +25NC, VTHM_T1 < VTHM <
VTHM_T2 or VTHM_T3 < VTHM <
VTHM_T4
4.05
4.075
4.1
TA = 0NC to +85NC, VTHM_T1 <
VTHM < VTHM_T2 or VTHM_T3 <
VTHM < VTHM_T4
4.034
4.075
4.1
LDO Load Regulation
%/mA
BATTERY CHARGER
BATT Regulation Voltage—Safety
IBATT = 0mA
Region 2
Maxim Integrated
V
3
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK,
UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER
CONDITIONS
BATT Recharge Threshold—
Safety Region 2
Change in VBATT
from DONE to fastcharge restart
BATT Fast-Charge
Current Range
RISET = 10kI to 2kI
BATT Charge Current Accuracy
VSYS = 5.5V,
VTHM_T1 < VTHM
< VTHM_T4 (safety
region 2)
MIN
TYP
MAX
VTHM_T2 < VTHM < VTHM_T3
-145
-104
-65
VTHM_T1 < VTHM < VTHM_T2 or
VTHM_T3 < VTHM < VTHM_T4
-120
-80
-40
0.3
RISET = 2kI
1350
1500
1650
RISET = 4kI
675
750
825
RISET = 10kI
270
300
330
RISET = 2kI, VBATT = 2.5V
(prequal)
270
300
330
RISET = 4kI, VBATT = 2.5V
(prequal)
130
150
170
RISET = 10kI, VBATT = 2.5V
(prequal)
ISET Output Voltage
RISET = 4kI, IBATT = 500mA (VISET = 1.5V at full
charge current) VTHM_T1 < VTHM < VTHM_T4
Charger Soft-Start Time
Charge-current ramp time
BATT Prequal Threshold
VBATT rising, 180mV hysteresis
BATT Input Current
VBATT = 4.2V,
ILDO = 0
1.5
UNITS
mV
A
mA
60
0.9
1
1.1
1.5
2.9
ms
3
3.1
No DC or USB power
connected, THMEN = low,
VCEN = 5V
5
12
No DC or USB power
connected, THMEN = high,
V CEN = 5V
12
25
0.003
2
DC or USB power connected,
V CEN = 5V
V
V
FA
DONE Threshold as a
Percentage of Fast-Charge
Current
IBATT decreasing
20
%
Maximum Prequal Time
From CEN falling to end of prequal charge, VBATT = 2.5V
180
min
Maximum Fast-Charge Time
From CEN falling to FLT falling
300
min
15
s
Maximum Top-Off Time
Timer Accuracy
-20
+20
%
Timer Extend Threshold
Percentage of fast-charge current below where the timer
clock operates at half-speed
50
%
Timer Suspend Threshold
Percentage of fast-charge current below where timer
clock pauses
20
%
4 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK,
UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER
THERMISTOR MONITOR (Beta = 3964) (Note 2)
THM Cold No-Charge Threshold
(T1)
CONDITIONS
ICHG = 0A, when charging is suspended, 2NC hysteresis
THM Cold Threshold (T2)
VBATT_REG, reduced, 2NC hysteresis
THM Hot Threshold (T3)
VBATT_REG reduced, 2.5NC hysteresis
THM Hot No-Charge Threshold
(T4)
ICHG = 0mA, when charging is suspended, 3NC
hysteresis
THM Hot Discharge Threshold
(TOT)
OT asserts low, 5NC hysteresis
THM Input leakage
THM = GND or LDO
THMSW Output Leakage
THMSW = GND
THMSW Output Voltage High
Sourcing 1mA
TA = +25NC
TA = +25NC
MAX
-2.1
0
+2.4
NC
76.4
77.2
77.9
8.2
10
12
NC
66.2
67
67.6
% of
THMSW
42.8
45
47.5
NC
% of
THMSW
29.8
30
30.6
57
60
63.5
NC
19.5
19.8
20.1
% of
THMSW
71
75
80
NC
12.6
12.9
13.1
% of
THMSW
-1
+0.001
+1
0.01
-0.2
+0.001
VIN = 0 to 5.5V
Logic-Low Output Voltage
Sinking 1mA
VOUT = 5.5V
+1
0.01
VLDO 0.05
FA
FA
V
1.3
Low level
Logic-Input Leakage Current
UNITS
% of
THMSW
TA = +85NC
0.4
Hysteresis
Logic-High Output Leakage
Current
TYP
TA = +85NC
LOGIC I/O: PEN1, PEN2, CHG, FLT, DONE, DOK, UOK, USUS, THMEN)
High level
Logic-Input Thresholds
MIN
50
V
mV
TA = +25NC
0.001
TA = +85NC
0.01
1
25
100
TA = +25NC
0.001
1
TA = +85NC
0.01
FA
mV
FA
Note 1: Limits are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design.
Note 2: NC includes external NTC thermistor error. % of THMSW excludes thermistor beta error and external pullup error. NTC
thermistor assumed to be 100kI Q1% nominal, part number Vishay NTHS0603N01N1003FF, external pullup resistor =
100kI Q1%.
Maxim Integrated
5
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
400
200
ENTERING OVLO
700
600
500
1
2
3
4
5
6
300
200
100
100
50
ENTERING OVLO
0
0
1
2
3
4
5
6
7
8
0
2
3
4
5
6
7
USB VOLTAGE (V)
BATTERY INPUT CURRENT
vs. BATTERY VOLTAGE
(USB DISCONNECTED)
BATTERY INPUT CURRENT
vs. TEMPERATURE
CHARGE CURRENT vs.
BATTERY VOLTAGE (100mA USB)
8
6
4
THMEN = 0
2
90
4.7
80
4.6
4.5
4.4
4.3
1
2
3
4
50
40
30
4.2
20
4.1
10
0
-40
5
-15
10
35
60
85
0
VUSB = 5V
PEN1 = X, PEN2 = 1
300
1200
250
200
150
100
VDC = 5V
PEN1 = 1, PEN2 = X
1000
CHARGE CURRENT (mA)
VBATT RISING
VBATT FALLING
350
3
4
5
CHARGE CURRENT
vs. BATTERY VOLTAGE (1A DC)
MAX8934G toc07
500
2
BATTERY VOLTAGE (V)
CHARGE CURRENT
vs. BATTERY VOLTAGE (500mA USB)
400
1
TEMPERATURE (°C)
BATTERY VOLTAGE (V)
450
VBATT RISING
VBATT FALLING
60
4.0
0
VUSB = 5V
PEN1 = X, PEN2 = 0
70
MAX8934G toc08
10
4.8
100
8
MAX8934G toc06
VBATT = 4V, THMEN = 0, ILDO = 0
USB AND DC UNCONNECTED
4.9
CHARGE CURRENT (mA)
THMEN = 1
5.0
BATTERY INPUT CURRENT (µA)
12
CHARGE CURRENT (mA)
1
USB VOLTAGE (V)
MAX8934G toc04
BATTERY INPUT CURRENT (uA)
150
USB VOLTAGE (V)
14
0
VBATT = 4.2V,
USUS = 1
200
0
8
7
VUSB RISING
VUSB FALLING
400
0
0
MAX8934G toc02
800
250
USB QUIESCENT CURRENT (FA)
VUSB RISING
VUSB FALLING
600
VBATT = 4.2V,
VUSUS = 0V
CEN = 1
ISYS = 0A
PEN1 = X, PEN2 = 1
MAX8934G toc05
800
USB OPERATING SUPPLY CURRENT (µA)
VBATT = 4.2V,
VUSUS = 0V
CHARGER IN
DONE MODE
ISYS = 0A
1000
900
MAX8934G toc01
USB OPERATIN SUPPLY CURRENT (µA)
1200
USB SUSPEND CURRENT
vs. USB VOLTAGE
USB OPERATING SUPPLY CURRENT
vs. USB VOLTAGE (CHARGER DISABLED)
MAX8934G toc03
USB OPERATING SUPPLY CURRENT
vs. USB VOLTAGE (CHARGER ENABLED)
VBATT RISING
VBATT FALLING
800
600
400
200
50
0
0
0
1
2
3
BATTERY VOLTAGE (V)
6 4
5
0
1
2
3
4
5
BATTERY VOLTAGE (V)
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
NORMALIZED CHARGE CURRENT
vs. AMBIENT TEMPERATURE
(LOW IC POWER DISSIPATION)
1.0050
1.0025
1.0000
0.9975
0.9950
0.9925
-15
4.210
4.205
4.200
4.195
4.190
4.185
4.180
10
35
60
85
4.170
-40
10
35
SYS OUTPUT VOLTAGE
vs. USB VOLTAGE
SYS OUTPUT VOLTAGE
vs. DC VOLTAGE
4.8
MAX8934G toc11
VBATT = 4.0V
NO SYS LOAD
VBATT = 4.0V
NO SYS LOAD
4.6
SYS VOLTAGE (V)
4.6
4.4
85
60
BATTERY VOLTAGE (V)
4.8
4.2
4.4
4.2
4.0
0
1
2
3
4
5
6
7
4.0
8
0
2
4
6
8
10
12
USB VOLTAGE (V)
DC VOLTAGE (V)
SYS OUTPUT VOLTAGE vs. SYS OUTPUT
CURRENT (USB AND DC DISCONNECTED)
SYS OUTPUT VOLTAGE
vs. SYS OUTPUT CURRENT (DC)
THE SLOPE OF THIS LINE
SHOWS THAT THE BATT-TO-SYS
RESISTANCE IS 40mI.
4.2
4.1
4.0
3.9
3.8
14
MAX8934G toc14
4.3
5.5
5.1
SYS VOLTAGE (V)
4.4
VBATT = 4.0V
MAX8934G toc13
4.5
4.7
VDC = 6V
4.3
3.9
VBAT = 4V
PEN1 = 1, PEN2 = X
CEN = 1
3.7
VDC = 5V
3.5
3.6
0
0.5
1.0
1.5
SYS OUTPUT CURRENT (A)
Maxim Integrated
-15
AMBIENT TEMPERATURE (°C)
MAX8934G toc12
-40
SYS VOLTAGE (V)
4.215
4.175
0.9900
SYS OUTPUT VOLTAGE (V)
MAX8934G toc10
1.0075
4.220
BATTERY REGULATION VOLTAGE (V)
VUSB = 5V, VBATT = 4V
MAX8943G toc09
NORMALIZED CHARGE CURRENT
1.0100
BATTERY REGULATION VOLTAGE
vs. TEMPERATURE
2.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
SYS CURRENT (A)
7
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
VL OUTPUT VOLTAGE vs.
DC VOLTAGE
SYS OUTPUT VOLTAGE vs.
SYS OUTPUT CURRENT (USB)
3.0
4.9
0.1A, PEN1 = 0, PEN2 = 0
4.7
4.5
MAX8934G toc16
0.5A, PEN1 = 0, PEN2 = 0
4.3
4.1
3.9
2.5
2.0
IVL = 5mA
1.5
1.0
IVL = 0mA
0.5
3.7
3.5
0
0
0.5
1.0
1.5
2.0
3.0
2.5
0
2
4
SYS OUTPUT CURRENT (A)
MAX8934G toc17
12
14
3.5
IBAT
BATTERY CURRENT (mA)
350
MAX8934G toc18
1.0
4.0
BATTERY VOLTAGE (V)
BATTERY CURRENT (mA)
400
VBAT
10
1.2
4.5
450
300
8
CHARGE PROFILE—820mAh BATTERY
ADAPTER INPUT—1A CHARGE
CHARGE PROFILE—820mAh BATTERY
USB INPUT—500mA CHARGE
500
6
DC VOLTAGE (V)
4.5
4.0
VBAT
3.5
0.8
IBAT
0.6
3.0
0.4
2.5
2.5
0.2
2.0
2.0
120
0
250
3.0
200
150
100
BATTERY VOLTAGE (V)
SYS OUTPUT VOLTAGE (V)
5.1
VL OUTPUT VOLTAGE (V)
VBATT = 4.0V,
VUSB = 5.0V
CEN = 1
5.3
3.5
MAX8934G toc15
5.5
50
0
0
20
40
60
80
100
1.5
0
20
MAX8934G toc19
4.35V
CDC CHARGING
IDC
5V/div
CSYS CHARGING
VBATT
VSYS
IDC
IUSB
5V/div
4.35V
CSYS CHARGING
1.2A
1A/div
0A
160mA
1A/div
-303mA
BATTERY CHARGER SOFT-START
400µs/div
8 5V/div
500mA/div
475mA
0A
IBATT
MAX8934G toc20
3.6V
3.6V
CDC
CHARGING
1A/div
1.2A
0A
80
DC CONNECT WITH NO USB
(RSYS = 22I)
DC CONNECT WITH USB CONNECTED
(RSYS = 22I)
VSYS
60
TIME (min)
TIME (min)
3.8V
40
-1A
0mA
IBATT
-1A
1A/div
BATTERY CHARGER SOFT-START
400µs/div
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
DC DISCONNECT WITH NO USB
(RSYS = 22I)
MAX8934G toc21
VBATT
MAX8934G toc22
5V/div
3.6V
VSYS
4V
3.6V
1.2A
VUSB
5V/div
475mA
CSYS CHARGING
IUSB
160mA
VSYS
3.3V
VUOK
3.3V
VCHG
3.3V
1A/div
-1A
IBATT
-IBATT = CHARGING
4.3V
IUSB
0V
475mA
VCHG
IBATT
MAX8934G toc24
-307mA
5V/div
VUSUS
IUSB
500mA/div
5V/div
3.3V
5V/div
3.3V
5V/div
160mA
500mA/div
3.6V
VCHG
3.3V
IBATT
160mA
5V/div
5V/div
500mA/div
VUSB = 5V
LDO OUTPUT VOLTAGE vs. LDO OUTPUT
CURRENT (USB DISCONNECTED)
3V
475mA
4.3V
500mA/div
3.7V
5V/div
3.3V
160mA
3.35
5V/div
0V
0A
BATTERY CHARGER
SOFT-START
-307mA
VUSB = 5V
200µs/div
Maxim Integrated
3.7V
500mA/div
USB RESUME (RSYS = 22I)
VSYS
IBATT
0A
200µs/div
3.6V
VCHG
475mA
5V/div
200µs/div
5V/div
500mA/div
VBATT = 4.0V
3.30
LDO OUTPUT VOLTAGE (V)
IUSB
3.3V
-307mA
MAX8934G toc25
VUSUS
0V
VSYS
3.6V
VUOK
500mA/div
USB SUSPEND (RSYS = 22I)
MAX8934G toc23
3.7V
5V/div
200µs/div
0mA
VSYS
5V/div
BATTERY CHARGER
-1A
SOFT-START -307mA
-150mA
USB DISCONNECT WITH NO DC
(RSYS = 22I)
4.2V
3.7V
5V/div
200µs/div
VUSB
500mA/div
CDC CHARGING
1A/div
0A
IBATT
5V/div
5V
MAX8934G toc26
IDC
USB CONNECT WITH NO DC
(RSYS = 22I)
3.25
DC UNCONNECTED
3.20
VDC = 5.0V
3.15
3.10
3.05
3.00
2.95
0
25
50
75 100 125 150
LDO OUTPUT CURRENT (mA)
175
9
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
LDO OUTPUT VOLTAGE vs.
BATTERY VOLTAGE
LDO STARTUP WAVEFORMS
MAX8934G toc27
VBATT
VLDO
3.0
2V/div
3.3V
2V/div
50mA/div
IBATT
MAX8934G toc28
3.5
3.6V
LDO OUTPUT VOLTAGE (V)
ILDO = 0
2.5
VBATT FALLING
2.0
VBATT RISING
1.5
1.0
0.5
0
400Fs/div
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BATTERY VOLTAGE (V)
ALWAYS-ON LDO POWER-SUPPLY
REJECTION RATIO vs. FREQUENCY
-15
PSRR (dB)
-20
-25
-30
-35
700
600
500
400
300
-40
200
-45
100
-50
MAX8934G toc30
VBATT = 3.8V,
ILDO = 10mA
RESISTIVE LOAD
800
OUTPUT NOISE (nV/Hz)
VSYS = 3.6V
ILDO = 10mA
RESISTIVE LOAD
-10
900
MAX8934G toc29
0
-5
LDO NOISE DENSITY
vs. FREQUENCY
0
0.1
1
10
100
0.01
FREQUENCY (kHz)
0.1
1
10
100
1000 10,000
FREQUENCY (kHz)
THM NORMAL TO
THM COLD (< T2) TRANSITION
MAX8934G toc31
1V/div
VTHM
2.2V
4.2V
4.075V
VBAT
200mV/div
420mA
IBAT
10I RESISTOR FROM BATT TO GND
200mA/div
10ms/div
10 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current
indicates charging.)
THM NORMAL TO THM HOT NO
CHARGE (> T4) TRANSITION
THM NORMAL TO THM HOT
(> T3) TRANSITION
MAX8934G toc33
MAX8934G toc32
0.65V
500mV/div
VTHM
1.0V
4.2V
4.2V
VBATT
500mV/div
VTHM
4.075V
IBATT
200mV/div
500mA/div
940mA
4.075V
VBATT
THM NORMAL TO T2 TO T1
(COLD, NO CHARGE) TRANSITION
MAX8934G toc35
MAX8934G toc34
2.2V
2V/div
3V
100mA/div
20ms/div
THM NORMAL TO THM HOT
THRESHOLD DISCHARGE TOT
VOT
0mA
HP6060B ELECTRONIC
LOAD SET TO CC MODE
10ms/div
VTHM
2V/div
100mA
IBATT
HP6060B ELECTRONIC LOAD
SET TO CC MODE
0V
1V/div
VTHM
0.425V
4.2V
2V/div
2.54V
4.075V
1V/div
VBATT
VBATT
2V/div
3.6V
420mA
VSYS
2V/div
3.6V
IBATT
0V
200mA/div
10I RESISTOR FROM BATT TO GND
0mA
4ms/div
Maxim Integrated
10ms/div
11
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Pin Description
PIN
NAME
1
DONE
FUNCTION
Charge Complete Output. The DONE active-low, open-drain output pulls low when the charger enters
the DONE state. The charger current = 0mA when DONE is low. See Figure 7.
DC Power Input. DC is capable of delivering up to 2A to SYS. DC supports both AC adapter and USB
inputs. The DC current limit is set with PEN1, PEN2, and RPSET. See Table 2. Both DC pins must be
connected together externally. Connect a 10FF ceramic capacitor from DC to GND. The DC inputs should
be grounded if not used.
2, 3
DC
4
CEN
Active-Low Charger Enable Input. Connect CEN to GND or drive low with a logic signal to enable
battery charging when a valid source is connected at DC or USB. Drive high with a logic signal to
disable battery charging.
5
PEN1
Input Limit Control 1. See Table 2 for complete information.
6
PEN2
Input Limit Control 2. See Table 2 for complete information.
7
PSET
DC Input Current-Limit Setting. Connect a resistor from PSET to GND to program the DC current limit up
to 2A (3000V/RPSET).
8
VL
9, 13
GND
10
CT
11
ISET
12
USUS
USB Suspend Digital Input. As shown in Table 2, driving USUS high suspends the DC or USB inputs if
they are configured as a USB power input.
THM
Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor with good thermal
contact with the battery from THM to GND. Use a thermistor with Beta = 3964. Connect a resistor
of equal resistance to the thermistor resistance at +25°C from THM to THMSW so that the battery
temperature can be monitored, and the fast-charge current and/or the charge termination voltage is
automatically adjusted, in accordance with safety region 2 of the JEITA specification.
14
15
16
12 Internal Logic LDO Output Bypass Pin. Provides 3.3V when DC or USB is present. Connect a 0.1FF
ceramic capacitor from VL to GND. VL powers the internal circuitry and provides up to 5mA to an
external load.
Ground. Both GND pins must be connected together externally.
Charge Timer Program Input. A capacitor from CT to GND sets the maximum prequal and fast-charge
timers. Connect CT to GND to disable the timer.
Charge Current-Limit Setting. A resistor (RISET) from ISET to GND programs the fast-charge charge
current up to 1.5A (3000V/RISET). The prequal charge current is 20% of the set fast-charge charge
current.
THMEN
Thermistor Enable Input. THMEN controls THMSW by connecting the external thermistor pullup resistor
and the thermistor monitoring circuit to LDO. Drive THMEN high to enable the thermistor circuit in
discharge mode and to connect the external thermistor pullup resistor. Drive THMEN low to disconnect
the external thermistor pullup resistor and to disable the thermistor monitoring circuit to conserve
battery energy when not charging.
THMSW
Thermistor Pullup Supply Switch. Drive THMEN high to enable the THMSW, shorting the THMSW output
to LDO. Drive THMEN low to open the THMSW switch. THMSW is always on when a valid input source
is present and the battery is being charged. When no input source is present, THMSW is controlled by
THMEN. THMSW is also active when the battery is being discharged, so that the battery temperature
can be monitored for an overtemperature condition.
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Pin Description (continued)
PIN
NAME
FUNCTION
17
LDO
Always-On Linear Regulator Output. LDO is the output of an internal always-on 3.3V LDO that provides
power to external circuitry. The LDO output provides up to 30mA of current for indicator LEDs or other
loads. LDO remains active even when only a battery is present, so that the thermistor monitor circuitry
can be activated when the battery is being discharged, and other circuitry can remain powered.
Connect a 1FF ceramic capacitor from LDO to GND.
18, 19
USB
USB Power Input. USB is capable of delivering up to 0.5A to SYS. The USB current limit is set with
PEN2 and USUS. See Table 2. Both USB pins must be connected together externally. Connect a 4.7FF
ceramic capacitor from USB to GND.
20, 21
BATT
Battery Connection. Connect the positive terminal of a single-cell Li+ battery to BATT. The battery
charges from SYS when a valid source is present at DC or USB. BATT powers SYS when neither DC nor
USB power is present, or when the SYS load exceeds the input current limit. Both BATT pins must be
connected together externally.
22
CHG
Charger Status Output. The CHG active-low, open-drain output pulls low when the battery is in fast
charge or prequal. Otherwise, CHG is high impedance.
23, 24
SYS
System Supply Output. SYS is connected to BATT through an internal 40mI system load switch when
DC or USB are invalid, or when the SYS load is greater than the input current limit.
When a valid voltage is present at DC or USB, SYS is limited to or 4.35V. When the system load (ISYS)
exceeds the DC or USB current limit, SYS is regulated to 75mV below VBATT and both the input and the
battery service the SYS load. Bypass SYS to GND with a 10FF ceramic capacitor. Both SYS pins must
be connected together externally.
25
OT
Battery Overtemperature Flag. The OT active-low, open-drain output pulls low when THMEN is high and
the battery temperature is R +75NC.
26
DOK
DC Power-OK Output. The DOK active-low, open-drain output pulls low when a valid input is detected
at DC.
27
UOK
USB Power-OK Output. The UOK active-low, open-drain output pulls low when a valid input is detected
at USB.
28
FLT
Fault Output. The FLT active-low, open-drain output pulls low when the battery timer expires before
prequal or fast charge complete.
—
EP
Exposed Pad. Connect the exposed pad to GND. Connecting the exposed pad does not remove the
requirement for proper ground connections to the appropriate pins.
Maxim Integrated
13
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
OT
LDO
DC POWER MANAGEMENT
DC
SYS
DC
SYS
PWR OK
3.3V ALWAYS-ON
LOW-IQ LDO
CHARGER
CURRENT AND
VOLTAGE
CONTROL
CURRENTLIMITED VOLTAGE
REGULATOR
DOK
Li+ BATTERY CHARGER
AND SYS LOAD SWITCH
ISET
BATT
SET INPUT
LIMIT
VL
BATT
VL LDO FOR
IC POWER
THERMISTOR
MONITOR
(SEE FIGURE 5)
USB POWER MANAGEMENT
THM
T
USB
THMSW
PWR OK
UOK
THMEN
CURRENTLIMITED VOLTAGE
REGULATOR
THERMAL
REGULATION
CHG
CHARGE
TERMINATION
AND MONITOR
SET INPUT
LIMIT
USUS
DONE
FLT
MAX8934G
PEN1
PEN2
CHG
INPUT AND
CHARGER
CURRENT-LIMIT
LOGIC CONTROL
CHARGE
TIMER
CT
CEN
PSET
GND
EP
Figure 1. Block Diagram
14 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
TO LDO
RPU
1MI
RPU
4x 1MI
1
CHARGE
DONE
ADAPTER
DONE
OT
MAX8934G
2 DC
CDC
10FF
3 DC
5
OFF
4
CHARGE ON
500mA
6
100mA
7
DOK
8
CVL
0.1FF
9, 13
CCT
0.068FF
THMSW
ACTIVE
DISABLED
10
15
16
14
100kI
NTC
100kI
25C
FAULT OUTPUT
27
USB PWR OK
26
DC PWR OK
SYS 23
CEN
CSYS
10FF
SYS 24
PEN2
TO
SYSTEM
LOAD
1MI
PSET
CHG
11
OVERTEMPERATURE
28
PEN1
RPSET
1.5kI
RISET
3kI
FLT
UOK
25
22
LDO
CHARGE
INDICATOR
BATT 20
ISET
BATT 21
1-CELL
Li+
CBATT
4.7FF
VL
USB 18
GND
CT
USB 19
THMEN
LDO
THMSW
1
CUSB
4.7FF
17
2
3
4
5
VBUS
DD+
ID
GND
CLDO
1FF
THM
EP
USUS
12
USB SUSPEND
Figure 2. Typical Application Circuit Using Separate DC and USB Connector
Maxim Integrated
15
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
TO LDO
5-PIN USB
CONNECTOR
VBUS
DD+
ID
GND
RPU
1MI
CHARGE
DONE
RPU
4x 1MI
1
DONE
2 DC
1
2
3
4
5
CDC
10FF
MAX8934G
4
CHARGE ON
DC
5
USB
500mA
6
100mA
7
DOK
RISET
3kI
8
CVL
0.1FF
9, 13
CCT
0.068FF
10
THMSW
ACTIVE
15
DISABLED
16
14
100kI
NTC
100kI
25C
25
OVERTEMPERATURE
28
FAULT OUTPUT
27
USB PWR OK
26
DC PWR OK
SYS 23
CEN
CSYS
10FF
SYS 24
PEN1
1MI
CHG
PEN2
PSET
22
VLDO
TO
SYSTEM
LOAD
CHARGE
INDICATOR
BATT 20
RPSET
1.5kI
11
FLT
UOK
3 DC
OFF
OT
BATT 21
CBATT
4.7FF
1-CELL
Li+
ISET
USB 18
VL
USB 19
GND
CT
LDO
17
CLDO
1FF
THMEN
THMSW
USUS
12
USB SUSPEND
THM
EP
Figure 3. Typical Application Circuit Using a 5-Pin USB Connector or Other DC/USB Common Connector
16 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Table 1. External Components List for Figures 2 and 3
COMPONENT
(Figures 2 and 3)
FUNCTION
CDC
DC filter capacitor
10FF ±10%, 16V X5R ceramic capacitor (0805)
Taiyo Yuden EMK212BJ106KG
CUSB
USB filter capacitor
4.7FF ±10%, 10V X5R ceramic capacitor (0805)
Taiyo Yuden LMK212BJ475KD
CVL
VL filter capacitor
0.1FF ±10%, 10V X5R ceramic capacitor (0402)
Taiyo Yuden LMK105BJ104KV
CSYS
SYS output bypass capacitors
10FF ±10%, 6.3V X5R ceramic capacitor (0805)
Taiyo Yuden JMK212BJ106KD
CBATT
Battery bypass capacitor
4.7FF ±10%, 6.3V X5R ceramic capacitor (0805)
Taiyo Yuden JMK212BJ475KD
CCT
Charger timing capacitor
0.068FF ±10%, 16V X5R ceramic capacitor (0402)
Taiyo Yuden EMK105BJ683KV
CLDO
LDO output capacitor
RPU (x5)
Logic-output pullup resistors
THM
Negative TC thermistor
PART NUMBER
1FF ±10%, 6.3V X5R ceramic capacitor (0402)
Taiyo Yuden JMK105BJ105KV
1MI ±5% resistor
Vishay NTC Thermistor P/N NTHS0603N01N1003FF
RTHMSW
THM pullup resistor
RPSET
DC input current-limit programming resistor
RISET
Fast-charge current programming resistor
Detailed Description
The MAX8934G is a dual-input linear charger with Smart
Power Selector that safely charges a single Li+/Li-Poly cell
in accordance with JEITA specifications. The MAX8934G
integrates power MOSFETs and control circuitry to manage
power flow in portable devices. See Figure 1. The charger
has two power inputs, DC and USB. These can be separately connected to an AC adapter output and a USB port,
or the DC input could be a single power input that connects
to either an adapter or USB. Logic inputs, PEN1 and PEN2,
select the correct current limits for two-input or single-input
operation. Figure 2 is the typical application circuit using
separate DC and USB connectors. Figure 3 is the typical
application circuit using a 5-pin USB connector or another
DC/USB common connector.
In addition to charging the battery, the MAX8934G also
supplies power to the system through the SYS output. The
charging current is also provided from SYS so that the set
input current limit controls the total SYS current, where total
SYS current is the sum of the system load current and the
battery-charging current. SYS is powered from either the
DC input pin or the USB input pin. If both the DC and USB
sources are connected, DC takes precedence.
Maxim Integrated
100kI
1.5kI ±1% for 2A limit
3kI ±1% for 1A charging
In some instances, there may not be enough adapter
current or USB current to supply peak system loads. The
MAX8934G Smart Power Selector circuitry offers flexible
power distribution from an AC adapter or USB source to
the battery and system load. The battery is charged with
any available power not used by the system load. If a
system load peak exceeds the input current limit, supplemental current is taken from the battery. Thermal limiting
prevents overheating by reducing power drawn from the
input source.
The MAX8934G features an overvoltage limiter at SYS. If
the DC or USB input voltage exceeds the SYS regulation
voltage, VSYS does not follow VDC or VUSB, but remains
at its regulation voltage. The MAX8934G has numerous
other charging and power-management features that are
detailed in the following sections.
A 3.3V ultra-low quiescent current, always-on LDO provides up to 30mA for indicator LEDs and for backup
power to the system. This LDO powers the thermistor
monitor circuitry and provides bias to the external pullup
resistor for the thermistor.
17
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Smart Power Selector
The MAX8934G Smart Power Selector seamlessly distributes power among the external inputs, the battery,
and the system load (see the Typical Operating Circuit).
The basic functions performed are:
U With both an external power supply (USB or adapter)
and battery connected:
U
When the system load requirements are less than
the input current limit, the battery is charged with
residual power from the input.
U
When the system load requirements exceed the
input current limit, the battery supplies supplemental current to the load.
U When the battery is connected and there is no external
power input, the system is powered from the battery.
U When an external power input is connected and there
is no battery, the system is powered from the external
power input.
System Load Switch
An internal 40mI MOSFET connects SYS to BATT (Q3
in the Typical Operating Circuit) when no voltage source
is available at DC or USB. When an external source is
detected at DC or USB, this switch is opened and SYS
is powered from the valid input source through the input
limiter.
The SYS-BATT switch also holds up SYS when the system
load exceeds the input current limit. If that should happen,
the SYS-BATT switch turns on so that the battery supplies
additional SYS load current. If the system load continuously exceeds the input current limit, the battery does not
charge, even though external power is connected. This is
not expected to occur in most cases, since high loads usually occur only in short peaks. During these peaks, battery
energy is used, but at all other times the battery charges.
Input Limiter
The input voltage limiter is essentially an LDO regulator. While in dropout, the regulator dissipates a small
I2R loss through the 0.2I MOSFET (Q1 in the Typical
Operating Circuit) between DC and SYS. With an AC
adapter or USB source connected, the input limiter
distributes power from the external power source to the
system load and battery charger. In addition to the input
limiter’s primary function of passing power to the system
and charger loads at SYS, it performs several additional
functions to optimize use of available power.
18 Input Voltage Limiting
If an input voltage is above the overvoltage threshold
(6.9V typ), the MAX8934G enters overvoltage lockout
(OVLO). OVLO protects the MAX8934G and downstream
circuitry from high-voltage stress up to 14V at DC and
8V at USB. In OVLO, VL remains on, the input switch that
sees overvoltage (Q1, Q2, Typical Operating Circuit)
opens, the appropriate power-monitor output (DOK,
UOK) is high impedance, and CHG is high impedance.
If both DC and USB see overvoltage, both input switches
(Q1 and Q2, Typical Operating Circuit) open and the
charger turns off. The BATT-to-SYS switch (Q3, Typical
Operating Circuit) closes, allowing the battery to power
SYS. An input is also invalid if it is less than BATT, or less
than the DC undervoltage threshold of 3.5V (falling). With
an invalid input voltage, SYS connects to BATT through a
40mI switch (Q3, Typical Operating Circuit).
Input Overcurrent Protection
The current at DC and USB is limited to prevent input
overload. This current limit can be selected to match the
capabilities of the source, whether it is a 100mA or 500mA
USB source, or an AC adapter. When the load exceeds
the input current limit, SYS drops to 75mV below BATT
and the battery supplies supplemental load current.
Thermal Limiting
The MAX8934G reduces input limiter current by 5%/NC
when its die temperature exceeds +100NC. The system
load (SYS) has priority over the charger current, so lowering the charge current first reduces the input current. If
the junction temperature still reaches +120NC in spite of
charge current reduction, no input (DC or USB) current
is drawn, the battery supplies the entire system load,
and SYS is regulated at 75mV below BATT. Note that
this on-chip thermal-limiting circuitry is not related to and
operates independently from the thermistor input.
Adaptive Battery Charging
While the system is powered from DC, the charger draws
power from SYS to charge the battery. If the charger
load plus system load exceeds the input current limit, an
adaptive charger control loop reduces charge current
to prevent the SYS voltage from collapsing. Maintaining
a higher SYS voltage improves efficiency and reduces
power dissipation in the input limiter. The total current
through the switch (Q1 or Q2 in the Typical Operating
Circuit) is the sum of the load current at SYS and the battery charging current. The MAX8934G limiter clamps at
4.35V, so input voltages greater than 4.35V can increase
power dissipation in the limiter. The MAX8934G input
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
limiter power loss is (VDC – VSYS) x IDC, where VSYS
may be as high as 4.35V. The input limiter power loss is
not less than 0.2I x IDC2. Also note that the MAX8934G
turns off when any input exceeds 6.9V (typ).
DC and USB Connections and
Current-Limit Options
Input Current Limit
The input and charger current limits are set as shown
in Table 2. It is often preferable to change the input
current limit as the input power source is changed. The
MAX8934G facilitates this by allowing different input current limits for DC and USB as shown in Table 2.
When the input current limit is reached, the first action
taken by the MAX8934G is to reduce the battery charge
current. This allows the regulator to stay in dropout during heavy loads, thus reducing power dissipation. If, after
the charge current is reduced to 0mA, the load at SYS
still exceeds the input current limit, SYS voltage begins
to fall. When the SYS voltage drops to BATT, the SYSto-BATT switch turns on, using battery power to support
the system load during the load peak. The MAX8934G
features flexible input connections (at the DC and USB
input pins) and current-limit settings (set by PEN1, PEN2,
PSET, and ISET) to accommodate nearly any input
power configuration. However, it is expected that most
systems use one of two external power schemes: separate connections for USB and an AC adapter, or a single
connector that accepts either USB or AC adapter output.
Input and charger current limit are controlled by PEN1,
PEN2, RPSET, and RISET, as shown in Table 2.
Separate Adapter and USB Connectors
When the AC adapter and USB have separate connectors, the adapter output connects to DC and the USB
source connects to USB. PEN1 is permanently connected
high (to DC or VL). The DC current limit is set by RPSET,
while the USB current limit is set by PEN2 and USUS.
Single Common Connector
for USB or Adapter
When a single common connector is used for both AC
adapter and USB sources, the DC input is used for
both input sources. The unused USB inputs should be
grounded when an AC adapter is connected at DC,
PEN1 should be pulled high to select the current limit
set by RPSET. When a USB source is connected, PEN1
should be low to select 500mA, 100mA, or USB suspend
(further selected by PEN2 and USUS). PEN1 can be
pulled up by the AC adapter power to implement hardware adapter/USB selection.
USB Suspend
Driving USUS high when PEN1 is low turns off the charger and reduces input current to 190FA to accommodate
USB suspend mode. The input limiter is disabled and
SYS is supported by BATT.
Power Monitor Outputs (UOK, DOK)
DOK is an open-drain output that pulls low when the DC
input has valid power. UOK is an open-drain output that
pulls low when the USB input has valid power. A valid
input for DC or USB is between 4.1V and 6.6V. If a single
power-OK output is preferred, DOK and UOK can be
wire-ORed together. The combined output then pulls low
if either USB or DC is valid.
Table 2. Input Limiter Control Logic
POWER
SOURCE
DOK
UOK
PEN1
PEN2
USUS
DC INPUT
CURRENT LIMIT
AC adapter at
DC input
L
X
H
X
X
3000V/RPSET
USB power at
DC input
L
X
L
H
L
475mA
L
X
L
L
L
95mA
USB suspend
USB power at
USB input; DC
unconnected
DC and USB
unconnected
L
X
L
X
H
H
L
X
H
L
H
L
X
L
L
H
L
X
X
H
H
H
X
X
X
USB INPUT
CURRENT LIMIT
USB input off;
DC input has
priority
3000V/RISET
475mA
95mA
0
475mA
No DC input
MAXIMUM CHARGE
CURRENT*
95mA
3000V/RISET
USB suspend
0
No USB input
0
*Charge current cannot exceed the input current limit. Actual charge current may be less than the maximum charge current if the
total SYS load exceeds the input current limit.
Maxim Integrated
19
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Soft-Start
To prevent input transients that can cause instability in
the USB or AC adapter power source, the rate of change
of input current and charge current is limited. When a
valid DC or USB input is connected, the input current
limit is ramped from zero to the set current-limit value (as
shown in Table 2). If DC is connected with no USB power
present, input current ramps in 1.5ms. If DC is connected with USB already present, input current ramps in
50Fs. When USB is connected with no DC present, input
current also ramps in 50Fs. If USB is connected with DC
already present, the USB input is ignored.
If an adapter is plugged into DC while USB is already
powered, the input current limit reramps from zero back
up to the DC current limit so that the AC adapter does
not see a load step. During this transition, if the input
current limit is below the SYS load current, the battery
supplies the additional current needed to support the
load. Additionally, capacitance can be added to SYS to
support the load during input power transitions. When
the charger is turned on, charge current ramps from zero
to the ISET current value in 1.5ms. Charge current also
ramps when transitioning to fast-charge from prequal
and when changing the USB charge current from 100mA
to 500mA with PEN2. There is no dI/dt limiting, however,
if ISET is changed suddenly using a switch at RISET.
Battery Charger
The battery charger state diagram is illustrated in Figure
7. With a valid DC or USB input, the battery charger
initiates a charge cycle when the charger is enabled. It
first detects the battery voltage. If the battery voltage is
less than the BATT prequal threshold (3.0V), the charger
enters prequal mode and charges the battery at 20% of
the maximum fast-charge current. This reduced charge
rate ensures that the maximum fast-charge current setting does not damage a deeply discharged battery.
Once the battery voltage rises to 3.0V, the charger transitions to fast-charge mode and applies the maximum
charge current. As charging continues, the battery voltage rises until it approaches the battery regulation voltage where charge current starts tapering down. When
charge current decreases to 20% of the fast-charge
current, the charger enters a brief 15s top-off state, then
DONE pulls low and charging stops. If the battery voltage subsequently drops below the recharge threshold,
charging restarts and the timers reset.
20 Charge Enable (CEN)
When CEN is low, the charger is on. When CEN is high,
the charger turns off. CEN does not affect the SYS output. In many systems, there is no need for the system
controller (typically a microprocessor) to disable the
charger, because the MAX8934G Smart Power Selector
circuitry independently manages charging and adapter/
battery power hand-off. In these situations, CEN can be
connected to ground.
Setting the Charge Current
ISET adjusts charge current to match the capacity of the
battery. A resistor from ISET to ground sets the maximum
fast-charge current:
ICHGMAX = 2000 x 1.5V/RISET = 3000V/RISET
Determine the ICHGMAX value by considering the characteristics of the battery. It is not necessary to limit the
charge current based on the capabilities of the expected
AC adapter/USB charging input, the system load, or
thermal limitations of the PCB. The MAX8934G automatically adjusts the charging algorithm to accommodate
these factors.
Monitoring the Charge Current
In addition to setting the charge current, ISET can also
be used to monitor the actual current charging the battery. See Figure 4. The ISET output voltage is:
VISET = ICHG x 1.5V/ICHGMAX = ICHG x RISET/2000
where ICHGMAX is the set fast-charge current and ICHG
is the actual battery charge current. A 1.5V output indicates the battery is being charged at the maximum set
fast charge current; 0V indicates no charging. This voltage is also used by the charger control circuitry to set
and monitor the battery current. Avoid adding more than
10pF capacitance directly to the ISET pin. If filtering of
the charge-current monitor is necessary, add a resistor
of 100kI or more between ISET and the filter capacitor
to preserve charger stability.
Note that the actual charge current can be less than the
set fast-charge current when the charger enters voltage
mode or when the input current limiter or thermal limiter
reduces charge current. This prevents the charger from
overloading the input source or overheating the system.
Charge Termination
When the charge current falls to the termination threshold
and the charger is in voltage mode, charging is complete. Charging continues for a brief 15s top-off period
and then enters the DONE state where charging stops.
The DONE current threshold (IDONE) is set to 20% of the
Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
charge-termination threshold (IDONE) and the charger is
in voltage mode. The charger exits the DONE state, and
fast-charge resumes, if the battery voltage subsequently
drops 104mV, or if input power or CEN is cycled. When
the MAX8934G is used in conjunction with a FP, connect a pullup resistor between DONE and the logic I/O
voltage to indicate charge status to the FP. Alternatively,
DONE can sink up to 20mA for an LED indicator.
Fault Output (FLT) and Charge Timer
FLT is an open-drain, active-low output that goes low
during a battery fault. The fault state occurs when either
the prequal or fast-charge timer expires. The prequal
and fast-charge fault timers are set by CCT:
MONITORING THE BATTERY
CHARGE CURRENT WITH VISET
VISET (V)
1.5
VISET
PREQUAL:
=
t PQ 180min ×
0
DISCHARGING
2000 (1.5V/RISET)
0
C CT
0.068FF
FAST CHARGE:
=
t FC 300min ×
C CT
0.068FF
BATTERY CHARGING CURRENT (A)
Figure 4. Monitoring the Battery Charge Current with VISET
fast-charge current setting. Note that if charge current
falls to IDONE as a result of the input or thermal limiter,
the charger does not enter the DONE state. For the charger to enter the DONE state, the charge current must be
less than IDONE, the charger must be in voltage mode,
and the input or thermal limiter must not be reducing the
charge current. The charger exits the DONE state, and
fast-charge resumes if the battery voltage subsequently
drops 104mV or if CEN is cycled.
Charge Status Outputs
TOP − OFF:t TO = 15s
While in fast-charge mode, a large system load or device
self-heating can cause the MAX8934G to reduce charge
current. Under these circumstances, the fast-charge
timer adjusts to ensure that adequate charge time is still
allowed. Consequently, the fast-charge timer is slowed
by 2x if charge current is reduced below 50% of the programmed fast-charge level. If charge current is reduced
to below 20% of the programmed level, the fast-charge
timer is paused. The fast-charge timer is not adjusted
if the charger is in voltage mode where charge current
reduces due to current tapering under normal charging.
Charge Output (CHG)
CHG is an open-drain, active-low output that is low during charging. CHG is low when the battery charger is in
its prequalification and fast-charge states. When charge
current falls to the charge termination threshold (IDONE)
and the charger is in voltage mode, CHG goes high
impedance. CHG goes high impedance if the thermistor
causes the charger to enter temperature suspend mode.
To exit a fault state, toggle CEN or remove and reconnect
the input source(s). Note also that thermistor out of range
or on-chip thermal-limit conditions are not considered
faults. When the MAX8934G is used in conjunction with a
FP, connect a pullup resistor between FLT and the logic
I/O voltage to indicate fault status to the FP. Alternatively,
FLT can sink up to 20mA for an LED indicator.
When the MAX8934G is used with a microprocessor (FP),
connect a pullup resistor between CHG and the logic I/O
voltage to indicate charge status to the FP. Alternatively,
CHG can sink up to 20mA for an LED indicator.
The MAX8934G thermistor monitor is configured to
execute JEITA recommendations regarding Li+/Li-Poly
battery charging by adjusting the fast charge current
and/or the charge termination voltage accordingly (see
Figure 6 ). Connect the THM input to an external negative
temperature coefficient (NTC) thermistor to monitor battery or system temperature. Since the thermistor monitoring circuit employs an external bias resistor from THM
to THMSW, the thermistor is not limited only to 10kI (at
Charge DONE Output (DONE)
DONE is an open-drain, active-low output that goes
low when charging is complete. The charger enters its
DONE state 15s after the charge current falls to the
Maxim Integrated
Thermistor Monitor
21
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
+25NC). Any thermistor resistance can be used as long
as the value of RTHMSW is equivalent to the thermistor’s
+25NC resistance. The MAX8934G THM thresholds are
optimized for a thermistor Beta of 3964. The general relation of thermistor resistance to temperature is defined by
the following equation:
=
R T R 25
the fast-charge current, depending on the sensed battery temperature. If the battery temperature exceeds the
THM hot overtemperature threshold and THMEN is high,
the OT flag pulls low. Typical systems connect OT to a
FP input so that the system can safely shut down.
Always-On LDO
 
1
1 
β 

T
273
C
298
+
°
°C 
×e 
The ultra-low quiescent current LDO is always on and is
preset to an output voltage of 3.3V. The LDO provides up
to 30mA output current. When DC and USB are invalid
and the battery is discharging, the LDO output voltage tracks VSYS as it drops below 3.3V. A 1FF ceramic
capacitor connected from LDO to GND is recommended
for most applications.
where:
RT = The resistance in ohms of the thermistor at
temperature T in NC
R25 = The resistance in ohms of the thermistor at
+25NC
Power Dissipation
PCB Layout and Routing
A = The material constant of the thermistor
Good design minimizes ground bounce and voltage
gradients in the ground plane. GND should connect to
the power-ground plane at only one point to minimize the
effects of power-ground currents. Battery ground should
connect directly to the power-ground plane. Connect
GND to the exposed pad directly under the IC. Use multiple tightly spaced vias to the ground plane under the
exposed pad to help cool the IC. Position input capacitors from DC, SYS, BATT, and USB to the power-ground
plane as close as possible to the IC. Keep high current
traces such as those to DC, SYS, and BATT as short and
wide as possible. Refer to the MAX8934A Evaluation Kit
for a suitable PCB layout example.
T = The temperature of the thermistor in NC
Charging is suspended when the thermistor temperature
is out of range (VTHM_T1 < VTHM or VTHM < VTHM_T4).
The charge timers are also suspended and hold their
state but no fault is indicated. When the thermistor
comes back into range, charging resumes and the
charge timer continues from where it left off.
The THMEN input controls THMSW and the thermistor
monitor circuitry when the battery charger is disabled,
providing the user with the means to minimize the battery current drain caused by the thermistor monitor. The
THMEN input is ignored while the battery is charging,
since the thermistor must be monitored at all times.
While charging, the thermistor monitor is used to automatically adjust the charge termination voltage and/or
Table 3. Package Thermal Characteristics
28-PIN 4mm x 4mm THIN QFN
SINGLE-LAYER PCB
MULTILAYER PCB
1666.7mW
(derate 20.8mW/NC above +70NC)
2285.7mW
(derate 28.6mW/NC above +70NC)
BJA
48NC/W
35NC/W
BJC
3NC/W
3NC/W
Continuous Power
Dissipation
22 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
SYS
LOW-IQ, ALWAYS-ON 3.3V LDO
TRACKS SYS WHEN DC AND USB ARE NOT
PRESENT, THE BATTERY IS BEING
DISCHARGED, AND VBATT P 3.3V.
LDO
CHG
VINT
CHG
THMEN
CHG
THMSW
CHARGER
CONTROL
RTHMSW
T4
(60NC)
+
OT
CHG
THERMISTOR
MONITOR
THM
VINT
VINT
VINT
T3
(45NC)
T
+
CHG
VINT
VINT
T2
(10NC)
+
CHG
VINT
VINT
TOT
(75NC)
+
NOT CHARGING
THMEN
VINT
VINT
T1
(0NC)
+
CHG
Figure 5. Thermistor Monitor Details
Maxim Integrated
23
MAX8934G
BATT REGULATION VOLTAGE (V)
(VBATT_REG)
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
T2
0
10
T1
T2
0
10
T3
T4
4.2
4.1
4.075
4.0
C
FAST-CHARGE CURRENT
(ICHG)
T1
25
45
60
TEMPERATURE (NC)
T3
T4
45
60
85
0.5C
25
85
TEMPERATURE (NC)
Figure 6. Safety Region 2: Fast-Charge Currents and Charge Termination Voltages
24 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
NOT READY
UOK AND DOK = HIGH-Z
CHG = HIGH-Z
FLT = HIGH-Z
DONE = HIGH-Z
ICHG = 0mA
CEN = HIGH
OR
REMOVE AND RECONNECT
THE INPUT SOURCE(S)
TOGGLE CEN
OR REMOVE AND RECONNECT
THE INPUT SOURCE(S)
UOK OR DOK = LOW
CEN = 0
RESET TIMER
STATE DIAGRAM IS FOR 10NC < TEMP < +45NC,
OUTSIDE OF THIS RANGE SEE FIGURE 6
ANY STATE
PREQUAL
UOK OR DOK = LOW
CHG = LOW
FLT = HIGH-Z
DONE = HIGH-Z
0V P VBATT P 3V
ICHG = ICHGMAX 10
VBATT > 3V,
RESET TIMER
VBATT < 2.82V,
RESET TIMER
FAST-CHARGE
VBATT < 2.82V
RESET TIMER
UOK OR DOK = LOW
CHG = LOW
FLT = HIGH-Z
DONE = HIGH-Z
3V P VBATT P 4.2V
ICHG = ICHGMAX
ICHG < IDONE
AND VBATT = 4.2V
AND THERMAL
OR OUTPUT LIMIT
NOT EXCEEDED
RESET TIMER
ICHG > IDONE
RESET TIMER
(PQ, FC, TOP-OFF)
ANY CHARGING
STATE
VTHM_T1 < VTHM < VTHM_T4
TIMER RESUME
VTHM_T1 < VTHM OR VTHM < VTHM_T4
TIMER SUSPEND
TEMPERATURE
SUSPEND
ICHG = 0mA
UOK OR DOK = PREVIOUS STATE
CHG = HIGH-Z
FLT = HIGH-Z
DONE = HIGH-Z
VTHM < VTHM_OT
VTHM > VTHM_OT
OVERTEMP
OT = LOW
TIMER > tPQ
FAULT
UOK AND DOK = LOW
CHG = HIGH-Z
FLT = LOW
DONE = HIGH-Z
ICHG = 0mA
TIMER > tFC
(TIMER SLOWED BY 2X IF
ICHG < ICHGMAX/2, AND
PAUSED IF ICHG < ICHGMAX/5
WHILE BATT < 4.2V)
TOP-OFF
UOK OR DOK = LOW
CHG = HIGH-Z
FLT = HIGH-Z
DONE = HIGH-Z
BATT = 4.2V
ICHG = IDONE
VBATT < 4.1V
RESET TIMER
TIMER > 15s
DONE
UOK OR DOK = LOW
CHG = HIGH-Z
FLT = HIGH-Z
DONE = LOW
4.1V < VBATT < 4.2V
ICHG = 0mA
Figure 7. Charger State Diagram
Maxim Integrated
25
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Pin Configuration
USB
USB
LDO
THMSW
THMEN
TOP VIEW
BATT
PROCESS: BiCMOS
BATT
Chip Information
21
20
19
18
17
16
15
CHG 22
14
THM
SYS 23
13
GND
12
USUS
11
ISET
DOK 26
10
CT
UOK 27
9
GND
8
VL
SYS 24
MAX8934G
OT 25
*EP
4
5
6
7
PEN1
PEN2
PSET
DC
3
CEN
2
DC
1
DONE
FLT 28
THIN QFN
*EXPOSED PAD
26 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Package Information
For the latest package outline information and land patterns, go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-”
in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to
the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
28 TQFN-EP
T2844+1
21-0139
90-0068
Maxim Integrated
27
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Package Information (continued)
For the latest package outline information and land patterns, go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-”
in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to
the package regardless of RoHS status.
28 Maxim Integrated
MAX8934G
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
Revision History
REVISION
NUMBER
REVISION
DATE
0
6/10
DESCRIPTION DATE
Initial release
PAGES
CHANGED
—
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2010
Maxim Integrated
29
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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