LTC4096/LTC4096X - Dual Input Standalone Li

LTC4096/LTC4096X - Dual Input Standalone Li
LTC4096/LTC4096X
Dual Input Standalone
Li-Ion Battery Chargers
FEATURES
DESCRIPTION
■
The LTC®4096/LTC4096X are standalone linear chargers
that are capable of charging a single-cell Li-Ion or Li-Polymer battery from both wall adapter and USB inputs. The
chargers can detect power at the inputs and automatically
select the appropriate power source for charging.
■
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■
■
■
■
■
■
■
■
Charges Single-Cell Li-Ion Battery from Wall
Adapter and USB Inputs
Automatic Input Detection (DC Input has Charging
Priority)
Charge Current Programmable up to 1.2A from
Wall Adapter Input
C/X Charge Current Termination
Input Power Present Output (PWR) with 120mA
Drive Capability
Independent DC, USB Charge Current Programming
Preset Float Voltage with ±0.6% Accuracy
Thermal Regulation Maximizes Charge Rate Without
Risk of Overheating*
Charge Status Output
Automatic Recharge
20µA Charger Quiescent Current in Shutdown
Available in a Thermally Enhanced, Low Profile
(0.75mm) 10-Lead (3mm × 3mm) DFN Package
Other features include trickle charge (LTC4096 only), automatic recharge, undervoltage lockout, charge status output
and power present output with 120mA drive capability.
APPLICATIONS
■
■
■
No external sense resistor or blocking diode is required
for charging due to the internal MOSFET architecture.
Internal thermal feedback regulates the battery charge
current to maintain a constant die temperature during high
power operation or high ambient temperature conditions.
The float voltage is fixed at 4.2V and the charge current
is programmed with an external resistor. The LTC4096
terminates the charge cycle when the charge current drops
below the user programmed termination threshold after
the final float voltage is reached. The LTC4096 can be put
into shutdown mode reducing the DCIN supply current to
20µA, the USBIN supply current to 10µA, and the battery
drain current to less than 2µA even with power applied
to both inputs.
Cellular Telephones
MP3 Players
Portable Handheld Devices
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. Patents including 6522118.
TYPICAL APPLICATION
1mF
1mF
ON OFF
DCIN
BAT
USBIN
PWR
IDC
1.24k
IUSB
2k
+
1k
SUSP
CHRG
ITERM
GND
2k
4096 TA01
4.2V
Li-Ion
BATTERY
BATTERY
CHARGE
VOLTAGE (V) CURRENT (mA)
USB
PORT
800mA (WALL)
500mA (USB)
LTC4096
WALL
ADAPTER
Complete Charge Cycle (1100mAh Battery)
1000
800
600
400
200
0
4.2
4.0
3.8
3.6
3.4
DCIN
VOLTAGE (V)
Dual Input Battery Charger for Single-Cell Li-Ion Battery
5.0
CONSTANT VOLTAGE
USBIN = 5V
TA = 25°C
RIDC = 1.24k
RIUSB = 2k
2.5
0
0
0.5
1.0
2.0
1.5
TIME (HR)
2.5
3.0
4096 TA01b
4096xf
1
LTC4096/LTC4096X
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1,7)
VDCIN, VUSBIN
t < 1ms and Duty Cycle < 1% .................. –0.3V to 7V
Steady State............................................. –0.3V to 6V
BAT, ⎯C⎯H⎯R⎯G, SUSP ........................................ –0.3V to 6V
IDC, IUSB, ITERM ...........................–0.3V to VCC + 0.3V
BAT Short-Circuit Duration............................Continuous
PWR Short-Circuit Duration ..........................Continuous
BAT, DCIN Pin Current (Note 6)..............................1.25A
USBIN Pin Current (Note 6) .....................................1.1A
IDC, IUSB, ITERM Pin Current ............................1.25mA
Junction Temperature ........................................... 125°C
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
TOP VIEW
10 BAT
DCIN
1
USBIN
2
PWR
3
CHRG
4
7 IUSB
SUSP
5
6 ITERM
9 IDC
11
8 GND
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 40°C/W (Note 3)
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
DD PART MARKING
LTC4096EDD
LTC4096XEDD
LCSJ
LCLM
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VDCIN = 5V, VUSBIN = 5V, RIDC = 1kΩ, RIUSB = 2kΩ, RITERM = 2kΩ unless
otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VDCIN
Adapter Supply Voltage
●
4.25
5.5
V
VUSBIN
USB Supply Voltage
●
4.25
5.5
V
IDCIN
DCIN Supply Current
Charge Mode (Note 4), RIDC = 10k
Standby Mode; Charge Terminated
Shutdown Mode (SUSP = 5V)
●
●
250
50
20
800
100
40
µA
µA
µA
IUSBIN
USBIN Supply Current
Charge Mode (Note 5), RIUSB = 10k, VDCIN = 0V
Standby Mode; Charge Terminated, VDCIN = 0V
Shutdown (VDCIN = 0V, SUSP = 5V)
VDCIN > VUSBIN
●
●
250
50
20
10
800
100
40
20
µA
µA
µA
µA
VFLOAT
Regulated Output (Float) Voltage
IBAT = 1mA
IBAT = 1mA, 0°C ≤ TA ≤ 85°C
4.179
4.158
4.2
4.2
4.221
4.242
V
V
IBAT
BAT Pin Current
RIDC = 1.25k, Constant-Current Mode
RIUSB = 2.1k, Constant-Current Mode
RIDC = 10k or RIUSB = 10k
Standby Mode, Charge Terminated
Shutdown Mode (Charger Disabled)
Sleep Mode (VDCIN = 0V, VUSBIN = 0V)
750
450
88
800
476
100
–5
–2
–5
850
500
112
–8
–4
–8
VIDC
IDC Pin Regulated Voltage
Constant-Current Mode, RIDC = 1.25k
1
V
VIUSB
IUSB Pin Regulated Voltage
Constant-Current Mode, RIUSB = 2k
1
V
mA
mA
mA
µA
µA
µA
4096xf
2
LTC4096/LTC4096X
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VDCIN = 5V, VUSBIN = 5V, RIDC = 1kΩ, RIUSB = 2kΩ, RITERM = 2kΩ unless
otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ITERMINATE
Charge Current Termination
Threshold
RITERM = 1k
RITERM = 2k
RITERM = 10k
88
42
6
100
50
9.5
112
58
13
mA
mA
mA
ITRIKL
Trickle Charge Current
(LTC4096 Only)
VBAT < VTRIKL; RIDC = 1k
VBAT < VTRIKL; RIUSB = 2k
85
42
100
50
115
58
mA
mA
VTRIKL
Trickle Charge Threshold Voltage VBAT Rising
(LTC4096 Only)
Hysteresis
2.8
2.9
135
3
V
mV
VUVDC
DCIN Undervoltage Lockout
Voltage
From Low to High
Hysteresis
4
4.22
200
4.4
V
mV
VUVUSB
USBIN Undervoltage Lockout
Voltage
From Low to High
Hysteresis
3.8
4
200
4.2
V
mV
VASD-DC
VDCIN – VBAT Lockout Threshold
Voltage
VDCIN from High to Low, VBAT = 4.3V
VDCIN from Low to High, VBAT = 4.3V
5
30
100
55
mV
mV
VASD-USB
VUSBIN – VBAT Lockout Threshold VUSBIN from High to Low, VBAT = 4.3V
Voltage
VUSBIN from Low to High, VBAT = 4.3V
5
30
150
55
mV
mV
VSUSP
VIL, Logic Low Voltage
0.5
V
●
VIH, Logic High Voltage
1.2
●
RSUSP
SUSP Pulldown Resistance
V⎯C⎯H⎯R⎯G
⎯C⎯H⎯R⎯G Output Low Voltage
I⎯C⎯H⎯R⎯G = 5mA
ΔVRECHRG
Recharge Battery Threshold
Voltage
VFLOAT – VRECHRG
tRECHRG
Recharge Comparator Filter Time VBAT from High to Low
tTERMINATE
Termination Comparator Filter
Time
RON-DC
1.3
●
30
V
3.4
7
MΩ
62
150
mV
50
80
mV
1.6
ms
3
ms
Power FET “ON” Resistance
(Between DCIN and BAT)
420
mΩ
RON-USB
Power FET “ON” Resistance
(Between USBIN and BAT)
470
mΩ
RDC-PWR
Power FET “ON” Resistance
(Between DCIN and PWR)
VDCIN = 5V, VUSBIN = 0V
15
Ω
RUSB-PWR
Power FET “ON” Resistance
(Between USBIN and PWR)
VDCIN = 0V, VUSBIN = 5V
6.6
Ω
TLIM
Junction Temperature in
Constant-Temperature Mode
115
°C
IBAT Drops Below Termination Threshold
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC4096 is guaranteed to meet the performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Failure to correctly solder the Exposed Pad of the package to the
PC board will result in a thermal resistance much higher than 40°C/W. See
Thermal Considerations.
Note 4: Supply current includes IDC and ITERM pin current (approximately
100µA each) but does not include any current delivered to the battery
through the BAT pin.
Note 5: Supply current includes IUSB and ITERM pin current
(approximately 100µA each) but does not include any current delivered to
the battery through the BAT pin.
Note 6: Guaranteed by long term current density limitations.
Note 7: VCC is greater of DCIN or USBIN
4096xf
3
LTC4096/LTC4096X
TYPICAL PERFORMANCE CHARACTERISTICS
Battery Regulated Output (Float)
Voltage vs Charge Current
4.26
4.26
4.215
4.205
4.20
4.20
4.200
VBAT (V)
4.22
4.18
4.18
4.16
4.190
4.14
4.14
4.185
4.12
4.12
4.180
4.10
200
400
600
800 1000
CHARGE CURRENT (mA)
100
0
1200
200
300
400
500
CHARGE CURRENT (mA)
4096 G01
4.26
4.24
4.22
4.20
4.20
VBAT (V)
4.22
4.18
4.16
4.14
4.14
4.12
4.12
4.50
4.75
5.00
VDCIN (V)
5.25
600
400
200
0
4.50
4.75
5.00
VUSBIN (V)
5.25
1.006
VUSBIN = 5V
RIUSB = 2k
1.006
VDCIN = 5V
RIDC = 10k
1.002
1.002
VIUSB (V)
400
VIDC (V)
1.004
1.000
0.998
0.998
100
0.996
0.996
0.4
0.6
0.8
1.0
1.2
VIUSB (V)
4096 G07
1.0
0.994
–50
–25
0
25
50
TEMPERATURE (°C)
75
1.2
100
4096 G08
VUSBIN = 5V
RIUSB = 10k
1.000
200
0.2
0.6
0.8
VIDC (V)
IUSB Pin Voltage vs Temperature
(Constant-Current Mode)
1.004
0
0.4
4096 G06
500
0
0.2
0
5.50
IDC Pin Voltage vs Temperature
(Constant-Current Mode)
300
VDCIN = 5V
RIDC = 1k
4096 G05
Charge Current vs IUSB Pin
Voltage
100
800
4096 G04
600
75
1000
4.10
4.25
5.50
1200
IBAT = 10mA
RIUSB = 2k
4.18
4.16
4.10
4.25
0
25
50
TEMPERATURE (°C)
Charge Current vs IDC Pin
Voltage
Battery Regulated Output (Float)
Voltage vs USBIN Voltage
IBAT = 10mA
RIDC = 1k
4.24
–25
4096 G03
IBAT (mA)
4.26
4.175
–50
600
4096 G02
Battery Regulated Output (Float)
Voltage vs DCIN Voltage
VBAT (V)
4.195
4.16
0
VDCIN = 5V
RIDC = 1k
VUSBIN = 5V
RIUSB = 2k
4.210
4.22
4.10
IBAT (mA)
Battery Regulated Output (Float)
Voltage vs Temperature
VUSBIN = 5V
RIUSB = 2k
4.24
VBAT (V)
VBAT (V)
Battery Regulated Output (Float)
Voltage vs Charge Current
VDCIN = 5V
RIDC = 1k
4.24
TA = 25°C, unless otherwise noted.
0.994
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4096 G09
4096xf
4
LTC4096/LTC4096X
TYPICAL PERFORMANCE CHARACTERISTICS
IDC Pin Voltage vs VDCIN
(Constant-Current Mode)
1.006
TA = 25°C, unless otherwise noted.
Recharge Threshold Voltage
vs Temperature
IUSB Pin Voltage vs VUSBIN
(Constant-Current Mode)
1.006
VBAT = 3.7V
RIDC = 10k
1.004
1.004
1.002
1.002
70
VBAT = 3.7V
RIUSB = 10k
VDCIN = VUSBIN = 5V
65
1.000
∆VRECHRG (mV)
VIUSB (V)
VIDC (V)
60
1.000
0.998
0.998
0.996
0.996
55
50
45
40
0.994
4.25
4.50
4.75
5.00
VDCIN (V)
5.25
5.50
35
0.994
4.25
4.50
4.75
5.00
VUSBIN (V)
5.25
4096 G10
575
1100
550
1050
525
475
900
450
850
425
3.2
3.4
3.6
VBAT (V)
3.8
RIDC = 1k
800
600 R
IUSB = 2k
400
3.2
3.4
3.6
VBAT (V)
3.8
4096 G13
200 VDCIN = VUSBIN = 5V
VBAT = 3.7V
θJA = 40°C/W
0
–50 –25
0
25
50
75
TEMPERATURE (°C)
4.0
100
4096 G14
Charge Current vs Supply Voltage
104
THERMAL REGULATION
1000
400
3.0
4.0
125
4096 G15
Charge Current vs Battery Voltage
Charge Current vs Battery Voltage
600
1200
VBAT = 3.7V
100
1200
VUSBIN = 5V
RIUSB = 2k
500
950
800
3.0
75
Charge Current vs Ambient
Temperature with Thermal
Regulation
IBAT (mA)
VDCIN = 5V
RIDC = 1k
1000
0
25
50
TEMPERATURE (°C)
4096 G12
Charge Current vs Battery Voltage
600
IBAT (mA)
IBAT (mA)
1150
–25
4096 G11
Charge Current vs Battery Voltage
1200
30
–50
5.50
LTC4096X
1000
500
800
400
LTC4096X
100
RIUSB = 10k
IBAT (mA)
RIDC = 10k
IBAT (mA)
IBAT (mA)
102
600
300
200
400
98
200
96
4.25
4.50
4.75
5.00
VDCIN, VUSBIN (V)
5.25
5.50
4096 G16
0
2.0
LTC4096
2.5
VDCIN = 5V
RIDC = 1k
θJA = 40°C/W
3.0
3.5
VBAT (V)
100
LTC4096
4.0
4.5
4096 G17
0
2.0
2.5
VUSBIN = 5V
RIUSB = 2k
θJA = 40°C/W
3.0
3.5
VBAT (V)
4.0
4.5
4096 G18
4096xf
5
LTC4096/LTC4096X
TYPICAL PERFORMANCE CHARACTERISTICS
DCIN Power FET On-Resistance
vs Temperature
550
550
VDCIN = 4V
IBAT = 200mA
20
VUSBIN = 4V
IBAT = 200mA
VDCIN = 5V
IPWR = 30mA
400
350
15
RPWRON (Ω)
RUSBON (mΩ)
500
450
450
400
–25
0
25
50
TEMPERATURE (°C)
75
300
–50
100
–25
0
25
50
TEMPERATURE (°C)
75
120
100
VDCIN = VUSBIN = 5V
VBAT = 4V
40
1
20
0
VCHRG (mV)
60
2
50
75
100
IPWR (mA)
125
150
0
VDCIN = VUSBIN = 5.5V
60
VDCIN = VUSBIN = 4.25V
40
1
2
3
4
5
0
–50
6
–25
VCHRG (V)
4096 G22
0
25
50
TEMPERATURE (°C)
75
4096 G23
Shutdown Supply Current vs
Temperature and VDCIN
4.5
VDCIN = VUSBIN = 5V
100
4096 G24
SUSP Pin Pulldown Resistance vs
Temperature
SUSP Pin Threshold Voltage
(On-to-Off) vs Temperature
100
20
0
25
75
ICHRG = 5mA
80
80
ICHRG (mA)
4
0
0
25
50
TEMPERATURE (°C)
⎯C⎯H⎯R⎯G Pin Output Low Voltage vs
Temperature
100
VUSBIN = 5V
VDCIN = 5V
–25
4096 G21
⎯C⎯H⎯R⎯G Pin I-V Curve
6
3
0
–50
100
4096 G20
VPWR vs IPWR
5
VUSBIN = 5V
IPWR = 30mA
5
4096 G19
VPWR (V)
10
350
300
–50
1000
PWR-DCIN and PWR-USBIN
Power FET On-Resistance vs
Temperature
USBIN Power FET On-Resistance
vs Temperature
500
RDCON (mΩ)
TA = 25°C, unless otherwise noted.
60
SUSP = VDCIN
VUSBIN = VDCIN
50
950
850
40
IDCIN (µA)
900
RSUSP (MΩ)
VSUSP (mV)
4.0
3.5
800
30
VDCIN = 5.5V
20
VDCIN = 4.25V
3.0
750
700
–50
10
–25
0
25
50
TEMPERATURE (°C)
75
100
4096 G25
2.5
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4096 G26
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4096 G27
4096xf
6
LTC4096/LTC4096X
TYPICAL PERFORMANCE CHARACTERISTICS
Shutdown Supply Current vs
Temperature and VUSBIN
60
TA = 25°C, unless otherwise noted.
Undervoltage Lockout Voltage
(Falling) vs Temperature
4.10
SUSP = VUSBIN
VDCIN = 0V
4.05
50
DCIN UVLO
4.00
3.95
VUV (V)
IUSBIN (µA)
40
30
VUSBIN = 5.5V
3.85
20
0
–50
USBIN UVLO
3.80
VUSBIN = 4.25V
10
3.90
3.75
–25
0
25
50
TEMPERATURE (°C)
75
100
3.70
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4096 G29
4096 G28
PIN FUNCTIONS
DCIN (Pin 1): Wall Adapter Input Supply Pin. Provides
power to the battery charger. The maximum supply
current is 1.2A. This pin should be bypassed with a 1µF
capacitor.
SUSP (Pin 5): Charge Enable Input. A logic low on this
pin enables the charger. If left floating, an internal 3.4MΩ
pull-down resistor defaults the LTC4096 to charge mode.
Pull this pin high for shutdown.
USBIN (Pin 2): USB Input Supply Pin. Provides power to
the battery charger. The maximum supply current is 1A.
This pin should be bypassed with a 1µF capacitor.
ITERM (Pin 6): Charge Termination Current Threshold
Program. The termination current threshold, ITERMINATE, is
set by connecting a resistor, RITERM, to ground. ITERMINATE
is set by the following formula:
PWR (Pin 3): Power Present Output. When the DCIN or
USBIN pin voltage is sufficient to begin charging (i.e. when
the DCIN or USBIN supply is greater than the undervoltage
lockout thresholds and at least 100mV or 150mV, respectively, above the battery terminal), the PWR pin is
connected to the appropriate input through an internal
P-channel MOSFET. If sufficient voltage to charge is not
present on DCIN or USBIN the PWR pin is high impedance.
This output is able to source up to 120mA.
⎯C⎯H⎯R⎯G (Pin 4): Open-Drain Charge Status Output. When
the LTC4096 is charging, the ⎯C⎯H⎯R⎯G pin is pulled low by
an internal N-channel MOSFET. When the charge cycle is
completed, ⎯C⎯H⎯R⎯G becomes high impedance. This output
is capable of sinking up to 10mA, making it suitable for
driving an LED.
ITERMINATE =
100V
RITERM
When the battery current, IBAT, falls below the termination
threshold, charging stops and the ⎯C⎯H⎯R⎯G output becomes
high impedance.
IUSB (Pin 7): Charge Current Program for USB Power.
The charge current is set by connecting a resistor, RIUSB,
to ground. When charging in constant-current mode, this
pin servos to 1V. The voltage on this pin can be used to
measure the battery current delivered from the USBIN
input using the following formula:
IBAT =
VIUSB
• 1000
RIUSB
4096xf
7
LTC4096/LTC4096X
PIN FUNCTIONS
GND (Pin 8): Ground.
IDC (Pin 9): Charge Current Program for Wall Adapter
Power. The charge current is set by connecting a resistor,
RIDC, to ground. When charging in constant-current mode,
this pin servos to 1V. The voltage on this pin can be used
to measure the battery current delivered from the DCIN
input using the following formula:
IBAT =
BAT (Pin 10): Charger Output. This pin provides charge
current to the battery and regulates the final float voltage
to 4.2V.
Exposed Pad (Pin 11): GND. The exposed backside of the
package is ground and must be soldered to PC board ground
for electrical connection and maximum heat transfer.
VIDC
•1000
RIDC
BLOCK DIAGRAM
DCIN
BAT
USBIN
1
10
2
CC/CV
REGULATOR
CC/CV
REGULATOR
DCON
+
USBON
+
–
4.2V
–
DCIN UVLO
USBIN UVLO
+
CHRG
4
+
–
BAT
10mA MAX
4V
–
BAT
RDC-PWR
DCIN
HIGH-Z
+
4.15V
RUSB-PWR
RECHARGE
LOGIC
3 PWR
USBIN
–
RECHRG
BAT
TRICKLE
DC_ENABLE
–
TERM
USB_ENABLE
CHARGER CONTROL
+
SUSP
TRICKLE
CHARGE*
2.9V
+
100mV
THERMAL
REGULATION
AND
SHUTDOWN
5
RSUSP
IBAT/1000
TERMINATION
IBAT/1000
+
–
–
TDIE
115°C
150°C
IBAT/1000
–
ITERM
6
IDC
9
IUSB
7
4096 BD
*NOT PRESENT IN THE "X" VERSION
RITERM
RIDC
GND
8, 11
RIUSB
4096xf
8
LTC4096/LTC4096X
OPERATION
The LTC4096 is designed to efficiently manage charging a
single-cell lithium-ion battery from two separate voltage
sources: a wall adapter and USB power bus. Using the
constant-current/constant-voltage algorithm, the charger
can deliver up to 1.2A of charge current from the wall
adapter supply or up to 1A of charge current from the
USB supply with a final float voltage accuracy of ±0.6%.
The LTC4096 has two internal P-channel power MOSFETs,
thermal regulation and shut down circuitry. No blocking
diodes or external sense resistors are required.
Power Source Selection
The LTC4096 can charge a battery from either the wall
adapter input or the USB port input. The LTC4096 automatically senses the presence of voltage at each input. If both
voltage sources are present, the LTC4096 defaults to the
wall adapter source provided sufficient voltage is present
at the DCIN input. “Sufficient voltage” is defined as:
• Supply voltage is greater than the UVLO threshold.
• Supply voltage is greater than the battery voltage by
30mV (100mV or 150mV rising, 30mV falling).
The power present output pin (PWR) indicates that sufficient input voltage is available. Table 1 describes the
behavior of this status output.
Programming and Monitoring Charge Current
The charge current delivered to the battery from the wall
adapter supply is programmed using a single resistor from
the IDC pin to ground.
RIDC =
1000 V
ICHRG(DC)
, ICHRG(DC) =
1000 V
RIDC
Similarly, the charge current from the USB supply is
programmed using a single resistor from the IUSB pin
to ground.
RIUSB =
1000 V
ICHRG(USB)
, ICHRG(USB) =
1000 V
RIUSB
Charge current out of the BAT pin can be determined at
any time by monitoring the IDC or IUSB pin voltage and
applying the following equations:
IBAT =
VIDC
• 1000, (ch arg ing from wall adapter )
RIDC
IBAT =
VIUSB
• 1000, (ch arg ing from USB sup ply)
RIUSB
Table 1. Power Source Selection
VUSBIN > 4V and
VUSBIN > BAT + 30mV
VUSBIN < 4V or
VUSBIN < BAT + 30mV
VDCIN > 4.2V and
VDCIN > BAT + 30mV
Charger powered from wall adapter source; Charger powered from wall adapter source
VPWR = VDCIN – RDC-PWR • IPWR
VPWR = VDCIN – RDC-PWR • IPWR
USBIN current < 25µA
VDCIN < 4.2V or
VDCIN < BAT + 30mV
Charger powered from USB source;
VPWR = VUSBIN – RUSB-PWR • IPWR
No charging
PWR: Hi-Z
4096xf
9
LTC4096/LTC4096X
OPERATION
Programming Charge Termination
The charge cycle terminates when the charge current
falls below the programmed termination threshold during
constant-voltage mode. This threshold is set by connecting an external resistor, RITERM, from the ITERM pin to
ground.
The charge termination current threshold (ITERMINATE) is
set by the following equation:
RITERM =
100V
ITERMINATE
, ITERMINATE =
100V
RITERM
The termination condition is detected by using an internal
filtered comparator to monitor the ITERM pin. When the
ITERM pin voltage drops below 100mV* for longer than
tTERMINATE (typically 3ms), the charge cycle terminates,
charge current latches off and the LTC4096 enters standby
mode. When charging, transient loads on the BAT pin can
cause the ITERM pin to fall below 100mV for short periods
of time before the DC charge current has dropped below
the programmed termination current. The 3ms filter time
(tTERMINATE) on the termination comparator ensures that
transient loads of this nature do not result in premature
charge cycle termination. Once the average charge current
drops below the programmed termination threshold, the
LTC4096 terminates the charge cycle and stops providing
any current out of the BAT pin. In this state, any load on
the BAT pin must be supplied by the battery.
Low-Battery Charge Conditioning (Trickle Charge)
This feature ensures that deeply discharged batteries are
gradually charged before applying full charge current. If
the BAT pin voltage is below 2.9V, the LTC4096 supplies
1/10th of the full charge current to the battery until the
BAT pin rises above 2.9V. For example, if the charger is
programmed to charge at 800mA from the wall adapter
input and 500mA from the USB input, the charge current
during trickle charge mode would be 80mA and 50mA,
respectively.
The LTC4096X has no trickle charge mode.
Automatic Recharge
In standby mode, the charger sits idle and monitors the
battery voltage using a comparator with a 1.6ms filter time
(tRECHRG). A charge cycle automatically restarts when the
battery voltage falls below 4.15V (which corresponds to
approximately 80%-90% battery capacity). This ensures
that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle
initiations. If the battery is removed from the charger, a
sawtooth waveform appears at the battery output. This
is caused by the repeated cycling between termination
and recharge events. This cycling results in pulsing at the
⎯C⎯H⎯R⎯G output; an LED connected to this pin will exhibit
a blinking pattern, indicating to the user that a battery is
not present. The frequency of the sawtooth is dependent
on the amount of output capacitance.
Status Indicators
⎯ H
⎯ R
⎯ G
⎯ ) has two states: pull-down
The charge status output (C
and high impedance. The pull-down state indicates that
the LTC4096 is in a charge cycle. Once the charge cycle
has terminated or the LTC4096 is disabled, the pin state
becomes high impedance. The pull-down state is capable
of sinking up to 10mA.
The power present output (PWR) has two states: DCIN/
USBIN voltages and high impedance. These states are
described in Table 1 and the circuit is shown in Figure
2. The high impedance state indicates that voltage is
not present at either DCIN or USBIN, so LTC4096 lacks
sufficient power to charge the battery. The PWR present
output is capable of sourcing up to 120mA steady state
and includes short circuit protection.
*Any external sources that hold the ITERM pin above 100mV will prevent the LTC4096 from
terminating a charge cycle.
4096xf
10
LTC4096/LTC4096X
APPLICATIONS INFORMATION
Manual Shutdown
The SUSP pin has a 3.4MΩ pulldown resistor to GND. A
logic low enables the charger and logic high disables it
(the pulldown defaults the charger to the charging state).
The DCIN input draws 20µA when the charger is in shutdown. The USBIN input draws 20µA during shutdown if
no power is applied to DCIN, but draws only 10µA when
VDCIN > VUSBIN.
Thermal Limiting
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise
above a preset value of approximately 115°C. This feature
protects the LTC4096 from excessive temperature and
allows the user to push the limits of the power handling
capability of a given circuit board without risk of damaging the device. The charge current can be set according
to typical (not worst case) ambient temperature with the
assurance that the charger will automatically reduce the
current in worst case conditions. A safety thermal shut
down circuit will turn off the charger if the die temperature
rises above a value of approximately 150°C. DFN power
considerations are discussed further in the Applications
Information section.
STARTUP
DCIN POWER APPLIED
ONLY USB POWER APPLIED
POWER SELECTION
DCIN POWER
REMOVED
TRICKLE CHARGE*
MODE
USBIN POWER
REMOVED OR
DCIN POWER
APPLIED
TRICKLE CHARGE*
MODE
BAT < 2.9V
BAT < 2.9V
1/10th FULL CURRENT
1/10th FULL CURRENT
CHRG STATE: PULLDOWN
PWR STATE: DCIN
CHRG STATE: PULLDOWN
PWR STATE: USBIN
BAT > 2.9V
2.9V < BAT
BAT > 2.9V
CHARGE
MODE
CHARGE
MODE
FULL CURRENT
CHRG STATE: PULLDOWN
PWR STATE: USBIN
CHRG STATE: PULLDOWN
PWR STATE: DCIN
IBAT < ITERMINATE
IN VOLTAGE MODE
IBAT < ITERMINATE
IN VOLTAGE MODE
BAT < 4.15V
SUSP
DRIVEN LOW
2.9V < BAT
FULL CURRENT
STANDBY
MODE
STANDBY
MODE
NO CHARGE CURRENT
NO CHARGE CURRENT
CHRG STATE: Hi-Z
PWR STATE: DCIN
CHRG STATE: Hi-Z
PWR STATE: USBIN
SUSP
DRIVEN HIGH
SHUTDOWN
MODE
SUSP
DRIVEN HIGH
IDCIN DROPS TO 20µA
CHRG STATE: Hi-Z
PWR STATE: DCIN
*NOT PRESENT IN THE "X" VERSION
SHUTDOWN
MODE
BAT < 4.15V
SUSP
DRIVEN LOW
IUSBIN DROPS TO 20µA
DCIN POWER
REMOVED
USBIN POWER
REMOVED OR
DCIN POWER
APPLIED
CHRG STATE: Hi-Z
PWR STATE: USBIN
4096 F01
Figure 1. LTC4096 State Diagram of a Charge Cycle
4096xf
11
LTC4096/LTC4096X
APPLICATIONS INFORMATION
Using a Single Charge Current Program Resistor
Stability Considerations
In applications where the programmed wall adapter charge
current and USB charge current are the same, a single
program resistor can be used to set both charge currents.
Figure 3 shows a charger circuit that uses one charge current program resistor. In this circuit, one resistor programs
the same charge current for each input supply.
The constant-voltage mode feedback loop is stable without
any compensation provided a battery is connected to the
charger output. However, a 4.7µF capacitor with a 1Ω
series resistor is recommended at the BAT pin to keep
the ripple voltage low when the battery is disconnected.
When the charger is in constant-current mode, the charge
current program pin (IDC or IUSB) is in the feedback loop,
not the battery. The constant-current mode stability is
affected by the impedance at the charge current program
pin. With no additional capacitance on this pin, the charger
is stable with program resistor values as high as 20KΩ
(ICHRG = 50mA); however, additional capacitance on these
nodes reduces the maximum allowed program resistor.
ICHRG(DC) = ICHRG(USB) =
1000 V
RISET
The LTC4096 can also program the wall adapter charge
current and USB charge current independently using two
program resistors, RIDC and RIUSB. Figure 4 shows a
charger circuit that sets the wall adapter charge current
to 800mA and the USB charge current to 500mA.
DCIN
USBIN
1
2
+
4.2V
+
–
–
DCIN UVLO
∆V
+–
DCON
USBON
4V
USBIN UVLO
+
+
–
–
BAT
10
–
BAT
10
DCON
–+
∆V
–
CURR-LIM
CURR-LIM
+
+
4096 BD
3 120mA MAX
PWR
Figure 2. Input Power Present Output (PWR) Circuit
4096xf
12
LTC4096/LTC4096X
APPLICATIONS INFORMATION
LTC4096
WALL
ADAPTER
USB
PORT
500mA
USBIN
1µF
1µF
+
IUSB
RISET
2k
1%
IDC
DCIN
ITERM
GND
BAT
USBIN
1µF
BAT
DCIN
800mA (WALL)
500mA (USB)
LTC4096
WALL
ADAPTER
USB
PORT
1µF
PWR
1k
4.2V
1-CELL
Li-Ion
BATTERY
IUSB
RIUSB
2k
1%
RITERM
1k
1%
RIDC
1.24k
1%
IDC
CHRG
ITERM
GND
RITERM
1k
1%
4096 F04
4096 F03
Figure 3. Dual Input Charger Circuit. The
Wall Adapter Charge Current and USB Charge
Current are Both Programmed to be 500mA
4.2V
1-CELL
Li-Ion
BATTERY
+
Figure 4. Full Featured Dual Input Charger Circuit
TA = 115°C – (5V – 3.3V) • (800mA) • 40°C/W
Power Dissipation
TA = 115°C – 1.36W • 40°C/W = 115°C – 54.4°C
When designing the battery charger circuit, it is not necessary to design for worst-case power dissipation scenarios
because the LTC4096 automatically reduces the charge
current during high power conditions. The conditions
that cause the LTC4096 to reduce charge current through
thermal feedback can be approximated by considering the
power dissipated in the IC. Most of the power dissipation
is generated from the internal MOSFET pass device. Thus,
the power dissipation is calculated to be:
TA = 60.6°C
PD = (VIN – VBAT) • IBAT
PD is the power dissipated, VIN is the input supply voltage (either DCIN or USBIN), VBAT is the battery voltage
and IBAT is the charge current. The approximate ambient
temperature at which the thermal feedback begins to
protect the IC is:
TA = 115°C – PD • θJA
TA = 115°C – (VIN – VBAT) • IBAT • θJA
Example: An LTC4096 operating from a 5V wall adapter (on
the DCIN input) is programmed to supply 800mA full-scale
current to a discharged Li-Ion battery with a voltage of 3.3V.
Assuming θJA is 40°C/W (see Thermal Considerations),
the ambient temperature at which the LTC4096 will begin
to reduce the charge current is approximately:
The LTC4096 can be used above 60.6°C ambient, but
the charge current will be reduced from 800mA. The approximate current at a given ambient temperature can be
approximated by:
IBAT =
105°C – TA
(VIN – VBAT ) • θ JA
Using the previous example with an ambient temperature
of 70°C, the charge current will be reduced to approximately:
105°C – 60°C
45°C
=
(5V – 3.3V)• 40°C / W 68°C / A
= 662mA
IBAT =
IBAT
It is important to remember that LTC4096 applications do
not need to be designed for worst-case thermal conditions,
since the IC will automatically reduce power dissipation
when the junction temperature reaches approximately
115°C. Moreover a thermal shut down protection circuit
around 150°C safely prevents any damage putting LTC4096
into shut down mode.
4096xf
13
LTC4096/LTC4096X
APPLICATIONS INFORMATION
Thermal Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on the
backside of the LTC4096 package is properly soldered
to the PC board ground. When correctly soldered to a
2500mm2 double sided 1oz copper board, the LTC4096
has a thermal resistance of approximately 40°C/W. Failure
to make thermal contact between the exposed pad on the
backside of the package and the copper board will result in
thermal resistances far greater than 40°C/W. As an example,
a correctly soldered LTC4096 can deliver over 800mA to
a battery from a 5V supply at room temperature. Without
a good backside thermal connection, this number would
drop to much less than 500mA.
Protecting the USB Pin and Wall Adapter Input from
Overvoltage Transients
Caution must be exercised when using ceramic capacitors
to bypass the USBIN pin or the wall adapter inputs. High
voltage transients can be generated when the USB or wall
adapter is hot plugged. When power is supplied via the
USB bus or wall adapter, the cable inductance along with
the self resonant and high Q characteristics of ceramic
capacitors can cause substantial ringing which could
exceed the maximum voltage ratings and damage the
LTC4096. Refer to Linear Technology Application Note 88,
entitled “Ceramic Input Capacitors Can Cause Overvoltage
Transients” for a detailed discussion of this problem.
Always use an oscilloscope to check the voltage waveforms at the USBIN and DCIN pins during USB and wall
adapter hot-plug events to ensure that overvoltage
transients have been adequately removed.
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity
voltage on the input supply pins is desired. If the supply voltage is high enough, a series blocking diode can
be used. In other cases where the voltage drop must be
kept low, a P-channel MOSFET can be used (as shown in
Figure 5).
DRAIN-BULK
DIODE OF FET
WALL
ADAPTER
LTC4096
DCIN
4096 F05
Figure 5. Low Loss Input Reverse Polarity Protection
4096xf
14
LTC4096/LTC4096X
PACKAGE DESCRIPTION
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 ±0.05
3.50 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
6
3.00 ±0.10
(4 SIDES)
0.38 ± 0.10
10
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
(DD10) DFN 1103
5
0.200 REF
1
0.75 ±0.05
0.00 – 0.05
0.25 ± 0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
4096xf
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC4096/LTC4096X
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC3455
Dual DC/DC Converter with USB Power
Management and Li-Ion Battery Charger
Efficiency >96%, Accurate USB Current Limiting (500mA/100mA),
4mm × 4mm QFN-24 Package
LTC4053
USB Compatible Monolithic Li-Ion Battery Charger
Standalone Charger with Programmable Timer, Up to 1.25A Charge Current
LTC4054/LTC4054X Standalone Linear Li-Ion Battery Charger
with Integrated Pass Transistor in ThinSOTTM
Thermal Regulation Prevents Overheating, C/10 Termination,
C/10 Indicator, Up to 800mA Charge Current
LTC4055
Charges Single-Cell Li-Ion Batteries Directly from USB Port,
Thermal Regulation, 4mm × 4mm QFN-16 Package
USB Power Controller and Battery Charger
LTC4058/LTC4058X Standalone 950mA Lithium-Ion Charger in DFN
C/10 Charge Termination, Battery Kelvin Sensing, ±7% Charge Accuracy
LTC4061
Standalone Li-Ion Charger with Thermistor Interface 4.2V, ±0.35% Float Voltage, Up to 1A Charge Current,
3mm × 3mm DFN-10 Package
LTC4061-4.4
Standalone Li-Ion Charger with Thermistor Interface 4.4V, ±0.4% Float Voltage, Up to 1A Charge Current,
3mm × 3mm DFN-10 Package
LTC4062
Standalone Li-Ion Charger with Micropower
Comparator
4.2V, ±0.35% Float Voltage, Up to 1A Charge Current,
3mm × 3mm DFN-10 Package
LTC4065/LTC4065A Standalone 750mA Li-Ion Charger
in 2mm × 2mm DFN
4.2V, ±0.6% Float Voltage, Up to 750mA Charge Current,
2mm × 2mm DFN-6 Package
LTC4066
Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and
Wall Adapter, Low-Loss (50mΩ) Ideal Diode, 4mm × 4mm QFN-24 Package
USB Power Controller and Li-Ion Linear Battery
Charger with Low-Loss Ideal Diode
LTC4068/LTC4068X Standalone Linear Li-Ion Battery Charger with
Programmable Termination
Charge Current up to 950mA, Thermal Regulation,
3mm × 3mm DFN-8 Package
LTC4069
Standalone Li-Ion Battery Charger with NTC
Thermistor Input in 2mm × 2mm DFN
4.2V, ±0.6% Float Voltage, Up to 750mA Charge Current, Timer Termination +
C/10 Detection Output
LTC4075
Dual Input Standalone Li-Ion Battery Charger
Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with
Automatic Input Power Detection and Selection, 950mA Charger Current,
Thermal Regulation, C/X Charge Termination, 3mm × 3mm DFN Package
LTC4076
Dual Input Standalone Li-Ion Battery Charger
Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with
Automatic Input Power Detection and Selection, 950mA Charger Current,
Thermal Regulation, C/X Charge Termination, 3mm × 3mm DFN Package
LTC4077
Dual Input Standalone Li-Ion Battery Charger
Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with
Automatic Input Power Detection and Selection, 950mA Charger Current,
Thermal Regulation, C/10 Charge Termination, 3mm × 3mm DFN Package
LTC4085
USB Power Manager with Ideal Diode Controller
and Li-Ion Charger
Charges Single-Cell Li-Ion Batteries Directly from a USB Port, Thermal
Regulation, 200mΩ Ideal Diode with <50mΩ option, 4mm × 3mm
DFN-14 Package
LTC4089/
LTC4089-5
USB Power Manager with Ideal Diode Controller and High Efficiency 1.2A Charger from 6V to 36V (40V Max) Input, Charges Single
High Efficiency Li-Ion Battery Charger
Cell Li-Ion Batteries Directly from a USB Port, Thermal Regulation; 200mΩ
Ideal Diode with <50mΩ Option, 4mm × 3mm DFN-14 Package, Bat-Track
Adaptive Output Control (LTC4089); Fixed 5V Output (LTC4089-5)
LTC4410
USB Power Manager and Battery Charger
Manages Total Power Between a USB Peripheral and Battery Charger, Ultralow
Battery Drain: 1µA, ThinSOT Package
LTC4411/LTC4412
Low Loss PowerPathTM Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing, Replaces ORing
Diodes
ThinSOT and PowerPath are trademarks of Linear Technology Corporation
4096xf
16 Linear Technology Corporation
LT 1006 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2006
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