SC810
Single Input/Single Mode
Single-cell Li-ion Charger
POWER MANAGEMENT
Features
Description
„
The SC810 is a linear single-cell Li-ion battery charger in a
6 lead 2×2mm MLPD Ultra-thin package. The input will
survive sustained input voltage up to 30V to protect
against hot plug overshoot and faulty charging adapters.
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Input voltage protection — 30V
Single input charger
Constant voltage — 4.2V, 1% regulation
Charging by current and voltage regulation (CC/CV)
Thermal limiting of charge current
Programmable fast-charge current
Current-limited adapter support — reduces power dissipation in charger IC
Instantaneous CC-to-CV transition for faster charging
Three termination options — float-charge, automatic
re-charge, or forced re-charge to keep the battery
topped-off after termination without float-charging
Soft-start reduces adapter load transients
High operating voltage range permits use of unregulated adapters
Complies with CCSA YD/T 1591-2006
Space saving 2×2×0.6 (mm) MLPD package
Pb free, Halogen free, and RoHS/WEEE compliant
Applications
„
Mobile phones
MP3 players
„ GPS handheld receivers
„
Charging begins automatically when a valid input source
is applied. Thermal limiting protects the SC810 from
excessive power dissipation. It can be programmed to
turn off when charging is complete or to continue operating as an LDO regulator while float-charging the battery.
The input will charge with an adapter operating in voltage
regulation or in current-limit to obtain the lowest possible
power dissipation by pulling the input voltage down to
the battery voltage. The maximum fast-charge current
setting is 1A.
Charge current is programmed with a single resistor. Precharge and termination current are fixed at 20% and 10%,
respectively, of the programmed fast-charge current.
Charge current steps up to the programmed value (soft
starts) to reduce load transients on the charging adapter.
Typical Application Circuit
SC810
VADAPTER
VIN
ENB
STATB
BAT
GND
IPRGM
Device
Load
2.2 μF
2.2 μF
Battery
Pack
September 17, 2009
© 2009 Semtech Corporation
1
SC810
Pin Configuration
VIN
Ordering Information
1
6
ENB
5
BAT
4
IPRGM
TOP VIEW
STATB
2
GND
3
Device
Package
SC810ULTRT(1)(2)
MLPD-UT-6 2×2
SC810EVB
Evaluation Board
Notes:
(1) Available in tape and reel only. A reel contains 3,000 devices.
(2) Pb free, halogen free, and RoHS/WEEE compliant.
T
MLPD-UT6; 2×2, 6 LEAD
θJA = 68°C/W
Marking Information
810
yw
yw = Date Code
2
SC810
Absolute Maximum Ratings
Recommended Operating Conditions
VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +30.0
Operating Ambient Temperature (°C) . . . . . . . . . -40 to +85
BAT, IPRGM (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.5
VIN Operating Voltage(2) (V) . . . . . . . . . . . . . . . . 4.60 to 8.20
STATB, ENB (V) . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to VBAT + 0.3
VIN Input Current (A). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5
BAT, IPRGM Short-to-Duration . . . . . . . . . . . . . Continuous
ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Thermal Information
Thermal Resistance, Junction to Ambient(3) (°C/W). . . . . 68
Maximum Junction Temperature (°C) . . . . . . . . . . . . . . +150
Storage Temperature Range (°C) . . . . . . . . . . . . -65 to +150
Peak IR Reflow Temperature (10s to 30s) (°C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not recommended.
NOTES:
(1) Tested according to JEDEC standard JESD22-A114D.
(2) This is the input voltage at which the charger is guaranteed to begin operation. This range, VTUVLO-R Max to VOVP-F Min, applies to charging
sources operating in voltage regulation. Charging sources operating in current limit may be pulled below this range by the charging load.
Maximum operating voltage is the maximum Vsupply as defined in EIA/JEDEC Standard No. 78, paragraph 2.11.
(3) Calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
Electrical Characteristics
Test Conditions: VVIN= 4.75V to 5.25V; CVIN = CBAT = 2.2μF; VBAT = 3.7V; Typ values at 25°C; Min and Max at -40°C < TA < 85°C, unless specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Units
4.30
4.45
4.60
V
2.70
2.85
3.00
V
9.6
V
VIN Under-Voltage Lockout
Rising Threshold
VTUVLO-R
VIN Under-Voltage Lockout Falling
Threshold (1)
VTUVLO-F
VIN OVP Rising Threshold
VTOVP-R
VIN OVP Falling Threshold
VTOVP-F
VIN OVP Hysteresis
VTOVP-H
VTOVP-R - VTOVP-F
VIN Charging Disabled Quiescent
Current
IqVIN_DIS
VENB = VBAT
2
3
mA
VIN Charging Enabled Quiescent
Current
IqVIN_EN
VENB = 0V, excluding IBAT and IIPRGM
2
3
mA
VCV
IBAT = 50mA, -40°C ≤ TJ ≤ 125°C
4.20
4.24
V
10
mV
CV Regulation Voltage
CV Voltage Load Regulation
Battery Leakage Current
VCV_LOAD
VVIN > VBAT
Relative to VCV @ 50mA, 1mA ≤ IBAT ≤ 1A,
-40°C ≤ TJ ≤ 125°C
8.2
V
50
mV
4.16
-20
lBAT_V0
VVIN = 0V
0.1
1
μA
lBAT_DIS
VVIN = 5V, VENB = 2V
0.1
1
μA
lBAT_MON
VVIN = 5V, VBAT = VCV, ENB not connected
0.1
1
μA
3
SC810
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Re-charge Threshold
VTReQ
VCV - VBAT
60
100
140
mV
Pre-charge Threshold (rising)
VTPreQ
2.85
2.90
2.95
V
IPRGM Programming Resistor
RIPRGM
2.05
29.4
kΩ
Fast-Charge Current, adapter mode
IFQ_AD
RIPRGM = 2.94kΩ, VTPreQ < VBAT < VCV
643
694
745
mA
Pre-Charge Current
IPreQ
RIPRGM = 2.94kΩ, 1.8V < VBAT < VTPreQ
105
139
173
mA
Termination Current
ITERM
RIPRGM = 2.94kΩ, VBAT = VCV
59
69
80
mA
Dropout Voltage
VDO
IBAT = 700mA, 0°C ≤ TJ ≤ 125°C
0.40
0.60
V
IPRGM Fast-charge Regulated Voltage
VIPRGM_FQ
VVIN = 5.0V, VTPreQ < VBAT < VCV
2.04
V
IPRGM Pre-charge Regulated Voltage
VIPRGM_PQ
1.8V < VBAT < VTPreQ
0.408
V
IPRGM Termination Threshold Voltage
VTIPRGM_TERM
VBAT = VCV
(either input selected)
0.204
V
Thermal Limiting Threshold Temperature
T TL
130
°C
Thermal Limiting Rate
iT
-50
mA/ °C
ENB Input High Voltage
VIH
1.6
ENB Input Mid Voltage
VIM
0.7
ENB Input Low Voltage
VIL
TJ > T TL
V
1.3
V
0.3
V
ENB Input High-range Threshold
Input Current
IIH_TH
ENB current required to pull ENB from
floating midrange into high range
23
50
μA
ENB Input High-range Sustain Input
Current
IIH_SUS
Current required to hold ENB in
high range, Min VIH ≤ VENB ≤ VBAT,
Min VIH ≤ VBAT ≤ 4.2V
0.3
1
μA
ENB Input Mid-range Load Limit
IIM
Input will float to mid range when this
load limit is observed.
-5
5
μA
ENB Input Low-range Input Current
IIL
0V ≤ VENB ≤ Max VIL
-25
IILEAK
VVIN = 0V, VENB = VBAT = 4.2V
1
μA
STATB Output Low Voltage
VSTAT_LO
ISTAT_SINK = 2mA
0.5
V
STATB Output High Current
ISTAT_HI
VSTAT = 5V
1
μA
ENB Input Leakage
-12
μA
Notes:
(1) Sustained operation to VTUVLO-F ≤ VVIN is guaranteed only if a current limited charging source applied to VIN is pulled below VTUVLO-R by the
charging load; forced VIN voltage below VTUVLO-R in some cases may result in regulation errors or other unexpected behavior.
4
SC810
Typical Characteristics
CV Line Regulation
CV Load Regulation
ο
ο
TA = 25 C, VVIN = 5V
4.204
4.204
4.2
4.2
4.196
4.196
VBAT (V)
VBAT (V)
TA = 25 C, IBAT = 50mA
4.192
4.192
4.188
4.188
4.184
4.184
4.18
5
5.5
6
6.5
7
7.5
4.18
0
8
100
200
300
CV Temperature Regulation
716
4.196
712
IBAT (mA)
VBAT (V)
4.2
4.192
704
4.184
700
20
40
60
80
100
696
4.5
120
5
5.5
6
o
CC FQ VBAT Regulation
716
716
712
712
IBAT (mA)
IBAT (mA)
720
708
704
700
700
VBAT (V)
8
708
704
3.5
7.5
VVIN = 5V, VBAT = 3.7V, RIPRGM = 2.94kΩ
720
3.3
7
CC FQ Temperature Regulation
ο
TA = 25 C, VVIN = 5V, RIPRGM = 2.94kΩ
3.1
6.5
VVIN (V)
Ambient Temperature ( C)
696
2.9
800
708
4.188
0
700
CC FQ Line Regulation
720
-20
600
TA = 25 C, VBAT = 3.7V, RIPRGM = 2.94kΩ
4.204
-40
500
ο
VVIN = 5V, IBAT = 50mA
4.18
400
IBAT (mA)
VVIN (V)
3.7
3.9
4.1
696
-40
-20
0
20
40
60
80
100
120
o
Ambient Temperature ( C)
5
SC810
Typical Characteristics (continued)
CC PQ Line Regulation
CC PQ Temperature Regulation
ο
VVIN = 5V, VBAT = 2.6V, RIPRGM = 2.94kΩ
160
160
156
156
152
152
IBAT (mA)
IBAT (mA)
TA = 25 C, VBAT = 2.6V, RIPRGM = 2.94kΩ
148
144
144
140
148
5
5.5
6
6.5
7
7.5
140
8
-40
-20
I vs. RIPRGM
160
IBAT (mA)
IBAT (mA)
800
600
80
100
120
120
400
80
200
40
14
60
I vs. RIPRGM
200
10
40
PQ
ο
VVIN = 5V, VBAT = 2.6V, TA = 25 C
1000
6
20
Ambient Temperature ( C)
FQ
ο
VVIN = 5V, VBAT = 3.7V, TA = 25 C
0
2
0
o
VVIN (V)
18
RIPRGM (kΩ)
22
26
30
0
2
6
10
14
18
22
26
30
RIPRGM (kΩ)
6
SC810
Typical Characteristics (continued)
Charging Cycle Battery Voltage and Current
Pre-Charging Battery Voltage and Current
ο
ο
850mAhr battery, RIPRGM = 2.94kΩ, VVIN = 5.0V, TA = 25 C
850mAhr battery, RIPRGM = 2.94kΩ, VVIN = 5.0V, TA = 25 C
800
4
700
6
600
5
500
700
400
3
300
IBAT
2
100
0.5
0.75
1
1.25
1.5
3.25
500
1.75
2
400
3
VBAT
2.75
300
2.5
200
2.25
100
0
2.25
2
0
2
4
6
Time (hrs)
CC-to-CV Battery Voltage and Current
12
14
16
18
0
20
Re-Charge Cycle Battery Voltage and Current
ο
850mAhr battery, RIPRGM = 2.94kΩ, VVIN = 5.0V, Load = 10mA
4.21
710
4.5
450
4
IBAT
4.19
670
4.18
650
VBAT
VBAT (V)
690
IBAT (mA)
VBAT (V)
10
Time (s)
850mAhr battery, RIPRGM = 2.94kΩ, VVIN = 5.0V, TA = 25 C
4.2
8
400
VBAT
3.5
350
3
300
2.5
250
2
200
1.5
4.17
630
IBAT (mA)
0.25
600
200
1
0
0
3.5
VBAT (V)
VBAT
4
IBAT
IBAT (mA)
VBAT (V)
3.75
IBAT (mA)
7
150
IBAT
1
100
0.5
50
Discharge hours 2 - 6 omitted.
4.16
44
44.5
45
45.5
46
Time (min)
46.5
47
47.5
610
48
0
0.0
0.5
1.0
1.5
2/6
6.5
7.0
0
7.5
Time (hrs)
7
SC810
Pin Descriptions
Pin #
Pin Name
Pin Function
1
VIN
2
STATB
Status output pin — This open-drain pin is asserted (pulled low) when a valid charging supply is connected to
VIN, and a charging cycle begins. It is released when the termination current is reached, indicating that charging is
complete. STATB is not asserted for re-charge cycles.
3
GND
Ground
4
IPRGM
Fast-charge and pre-charge current programming pin — Fast-charge current is programmed by connecting
a resistor from this pin to ground. Pre-charge current is 20% of fast-charge current. The charging termination
threshold current is 10% of the IPRGM programmed fast-charge current.
5
BAT
Charger output — connect to battery positive terminal.
6
ENB
Combined device enable/disable — Logic high disables the device. Connect to GND to enable charging with
indefinite float-charging. Float this pin to enable charging without float-charge upon termination. Note that this
pin must be grounded if the SC810 is to be operated without a battery connected to BAT.
T
Thermal Pad
Pad is for heat sinking purposes — not connected internally. Connect exposed pad to ground plane using multiple vias.
Supply pin — connect to charging adapter (wall adapter or USB). This is a high voltage (30V) pin.
8
SC810
Block Diagram
V_Adapter
1
VIN
System
Supply
Regulator
Connect to BAT or
to regulated supply
VCV = 4.2V
CV
CC
VIREF
To
System
Load
BAT
5
Die
Temperature
VT_CT
2
LithiumIon
Single
Cell
Battery
Pack
Thermal
Limiting
STATB
Precharg, CC/CV
& Termination
Controller, Logical
State Machine
Termination
VTIPRGM_TERM
VTENB_HIGH = ~1.50V
1V
Tri-level
Control
VTENB_LOW = ~0.55
ENB
IPRGM
6
GND
4
3
RIPRGM
9
SC810
Applications Information
Charger Operation
The SC810 is a single cell Li-ion battery charger. It implements a Constant Current (CC), Constant Voltage (CV)
charging algorithm with Thermal Limiting (TL).
When a valid input supply is first detected, a charge cycle
is initiated and the STATB open-drain output goes low. If
the battery voltage is less than the pre-charge threshold
voltage, the pre-charge current is supplied. Pre-charge
current is 20% of the programmed fast-charge current.
When the battery voltage exceeds the pre-charge threshold, typically within seconds for a standard battery with a
starting cell voltage greater than 2V, the fast-charge CC
mode begins. The charge current soft-starts in three steps
(20%, 60%, and 100% of programmed fast-charge current)
to reduce adapter load transients. CC current is programmed by the IPRGM resistance to ground.
The charger begins CV regulation when the battery
voltage rises to the fully-charged single-cell Li-ion regulation voltage (VCV ), nominally 4.2V. In CV regulation, the
output voltage is regulated, and as the battery charges,
the charge current gradually decreases. The STATB output
goes high when IBAT drops below the termination threshold current, which is 10% of the IPRGM pin programmed
fast-charge current. This is known as charge termination.
Optional Float-charging or Monitoring
Depending on the state of the ENB input, upon termination, the SC810 either operates indefinitely as a voltage
regulator (float-charging) or it turns off its output. If the
output is turned off upon termination, the device enters
the monitor state. In this state, the output remains off
until the BAT pin voltage decreases by the re-charge
threshold (VTReQ = 100mV typically). A re-charge cycle
then begins automatically and the process repeats. A
forced re-charge cycle can also be periodically commanded by the processor to keep the battery topped-off
without float-charging. See the Monitor State section for
details. Re-charge cycles are not indicated by the STATB
pin.
Charging Input Pin Properties
(UVLO) threshold will not be recognized until the ringing
has ceased. The UVLO rising threshold is set higher than
the voltage of a fully charged Li-ion single cell battery,
ensuring that only a charging source capable of fully
charging the battery has been applied. If the charging
current loads the adapter beyond its current limit, the
input voltage will be pulled down to just above the
battery voltage. This is referred to as Current-LimitedAdapter (CLA) operation. The UVLO falling threshold is
set close to the battery voltage pre-charge threshold to
permit low-dissipation charging from a current limited
adapter.
Constant Current Mode Fast-charge Current
Programming
The CC mode is active when the battery voltage is above
VTPreQ and less than VCV. The programmed CC regulation
fast-charge (FQ) current is inversely proportional to the
resistance between IPRGM and GND according to the
equation
IFQ
VIPRGM _ Typ
u 1000
RIPRGM
The fast-charge current can be programmed for a
minimum of 70mA (RIPRGM = 29.4kΩ) and a maximum of
995mA (RIPRGM = 2.05kΩ), nominally.
Current regulation accuracy is dominated by gain error at
high current settings, and offset error at low current settings. The range of expected fast-charge output current
versus programming resistance is shown in Figures 1a
and 1b. The figures show the nominal current versus
nominal RIPRGM resistance as the center plot and two theoretical limit plots indicating maximum and minimum
current versus nominal programming resistance. These
plots are derived from models of the expected worst-case
contribution of error sources depending on programmed
current. The current range includes the uncertainty due
to 1% tolerance resistors. The dots on each plot indicate
the currents obtained with the Electronic Industries
Association (EIA) E96 standard value 1% tolerance resistors. Figures 1a and 1b show low and high resistance
ranges, respectively.
Glitch filtering is performed on the VIN pin, so an input
voltage that is ringing across its Under-Voltage Lockout
10
SC810
Applications Information (continued)
1100
325
1050
300
1000
950
275
250
850
Fast-charge Current (mA)
Fast-charge Current (mA)
900
800
750
700
650
600
550
500
225
200
175
150
125
450
100
400
350
75
300
250
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
50
7
7
8
9
RIPRGM (kΩ), R-tol = 1%
RIPRGM (kΩ), R-tol = 1%
Figure 1a — Fast-charge Current Tolerance versus
Programming Resistance, Low Resistance Range
Pre-charge Mode
This mode is automatically enabled when the battery
voltage is below the pre-charge threshold voltage (VTPreQ),
typically 2.9V. Pre-charge current conditions the battery
for fast charging. The pre-charge current value is fixed at
20% nominally of the fast-charge current for the selected
input, as programmed by the resistance between IPRGM
and GND.
Pre-charge current regulation accuracy is dominated by
offset error. The range of expected pre-charge output
Figure 1b — Fast-charge Current Tolerance versus
Programming Resistance, High Resistance Range
current versus programming resistance is shown in
Figures 2a and 2b. The figures show the nominal precharge current versus nominal RIPRGM resistance as the
center plot and two theoretical limit plots indicating
maximum and minimum current versus nominal programming resistance. These plots are derived from
models of the expected worst-case contribution of error
sources depending on programmed current. The current
range includes the uncertainty due to 1% tolerance resistors. The dots on each plot indicate the currents obtained
with the EIA E96 standard value 1% tolerance resistors.
80
270
260
75
70
230
220
65
210
60
200
190
55
Pre-charge Current (mA)
Pre-charge Current (mA)
250
240
180
170
160
150
140
130
120
110
100
50
45
40
35
30
25
90
20
80
70
15
10
60
50
5
40
30
2
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
0
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
RIPRGM (kΩ), R-tol = 1%
Figure 2a — Pre-charge Current Tolerance versus
Programming Resistance, Low Resistance Range
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
RIPRGM (kΩ), R-tol = 1%
Figure 2b — Pre-charge Current Tolerance versus
Programming Resistance, High Resistance Range
11
SC810
Applications Information (continued)
Figures 2a and 2b show low and high resistance ranges,
respectively.
Termination
When the battery voltage reaches VCV, the SC810 transitions from constant current regulation to constant voltage
regulation. While VBAT is regulated to VCV, the current into
the battery decreases as the battery becomes fully
charged. When the output current drops below the termination threshold current, fixed at 10% of the programmed
fast-charge current, charging terminates. Upon termination, the STATB pin open drain output turns off and the
charger either enters monitor state or float-charges the
battery, depending on the logical state of the ENB input
pin.
Charger output current is the sum of the battery charge
current and the system load current. Battery charge
current changes gradually, and establishes a slowly diminishing lower bound on the output current while charging
in CV mode. The load current into a typical digital system
is highly transient in nature. Charge cycle termination is
detected when the sum of the battery charging current
and the greatest load current occurring within the immediate 300μs to 550μs past interval is less than the programmed termination current. This timing behavior
permits charge cycle termination to occur during a brief
low-load-current interval, and does not require that the
longer interval average load current be small.
Termination threshold current accuracy is dominated by
offset error. The range of expected termination current
versus programming resistance is shown in Figures 3a
and 3b. The figures show the nominal termination current
versus nominal RIPRGM resistance as the center plot and
two theoretical limit plots indicating maximum and
minimum current versus nominal programming resistance. These plots are derived from models of the
expected worst-case contribution of error sources
depending on programmed current. The current range
includes the uncertainty due to a 1% tolerance resistor.
The dots on each plot indicate the currents obtained with
the EIA E96 standard value 1% tolerance resistors. Figures
3a and 3b show low and high resistance ranges,
respectively.
Enable Input
The ENB pin is a tri-level logical input that allows selection of the following behaviors:
ƒ
charging enabled with float-charging
after termination (ENB = low range)
charging enabled with float-charging disabled and battery monitoring at termination (ENB = mid range)
charging disabled (ENB = high range).
ƒ
ƒ
The ENB pin is designed to interface to a processor GPIO
port powered from a peripheral supply voltage as low as
115
35
110
105
30
95
Termination Current Threshold (mA)
Termination Current Threshold (mA)
100
90
85
80
75
70
65
60
55
50
45
25
20
15
10
40
35
5
30
25
20
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
RIPRGM (kΩ), R-tol = 1%
Figure 3a — Termination Current Tolerance versus
Programming Resistance, Low Resistance Range
0
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
RIPRGM (kΩ), R-tol = 1%
Figure 3b — Termination Current Tolerance versus
Programming Resistance, High Resistance Range
12
SC810
Applications Information (continued)
1.8V or as high as a fully charged battery. While a connected GPIO port is configured as an output, the processor writes 0 to select ENB low-range, and 1 to select
high-range. The GPIO port is configured as an input to
select mid-range.
ENB can also be permanently grounded to select lowrange or left unconnected to select mid-range if it will not
be necessary to change the level selection.
The equivalent circuit looking into the ENB pin is a variable resistance, minimum 15kΩ, to an approximately 1V
source. The input will float to mid range whenever the
external driver sinks or sources less than 5μA, a common
worst-case characteristic of a high impedance or a weak
pull-up or pull-down GPIO configured as an input. The
driving GPIO must be able to sink at least 25μA or source
at least 50μA to ensure a low or high state, respectively.
(See the Electrical Characteristics table.)
With the ENB input voltage permitted to float to midrange, the charger is enabled but it will turn off its output
following charge termination and will enter the monitor
state. This state is explained in the next section. Midrange can be selected either by floating the input (sourcing or sinking less than 5μA) or by being externally forced
such that VENB falls within the midrange limits specified in
the Electrical Characteristics table.
While driven low (VENB < Max VIL), the charger is enabled
and will continue to float-charge the battery following
termination. If the charger is already in monitor state following a previous termination, it will exit the monitor state
and begin float-charging.
While ENB is driven high (VENB > Min VIH), the charger is disabled and the ENB input pin enters a high impedance state,
suspending tri-level functionality. The specified high level
input current IIH is required only until a high level is recognized by the SC810 internal logic. The tri-level float circuitry
is then disabled and the ENB input becomes high impedance. Once forced high, the ENB pin will not float to mid
range. To restore tri-level operation, the ENB pin must first
be pulled down to mid or low range (at least to
VENB < Max VIM), then, if desired, released (by reconfiguring
the GPIO as an input) to select mid-range. If the ENB GPIO
has a weak pull-down when configured as an input, then it
is unnecessary to drive ENB low to restore tri-level operation; simply configure the GPIO as an input. When the ENB
selection changes from high-range to mid- or low-range, a
new charge cycle begins and STATB goes low.
Note that if a GPIO with a weak pull-up input configuration is used, its pull-up current will flow from the GPIO into
the ENB pin while it is floating to mid-range. Since the
GPIO is driving a 1V equivalent voltage source through a
resistance (looking into ENB), this current is small — possibly less than 1μA. Nevertheless, this current is drawn
from the GPIO peripheral power supply and, therefore,
from the battery after termination. See the next section,
Monitor State for more information. For this reason, it is
preferable that the GPIO chosen to operate the ENB pin
should provide a true high impedance (CMOS) configuration or a weak pull-down when configured as an input.
When pulled below the float voltage, the ENB pin output
current is sourced from VIN (the charging adapter), not
from the battery.
Monitor State
If the ENB pin is floating, the charger output and STATB pin
will turn off and the device will enter the monitor state
when a charge cycle is complete. If the battery voltage
falls below the re-charge threshold (VCV - VReQ) while in the
monitor state, the charger will automatically initiate a recharge cycle. The battery leakage current during monitor
state is no more than 1μA over temperature and typically
less than 0.1μA at room temperature.
While in the monitor state, the ENB tri-level input pin
remains fully active, and although in midrange, is sensitive
to both high and low levels. The SC810 can be forced from
the monitor state (no float-charging) directly to floatcharging operation by driving ENB low. This operation will
turn on the charger output, but will not assert the STATB
output. If the ENB pin is again allowed to float to midrange, the charger will remain on only until the output
current becomes less than the termination current, and
charging terminates. The SC810 turns off its charging
output and returns to the monitor state within a millisecond. This forced re-charge behavior is useful for periodically testing the battery state-of-charge and topping-off
the battery, without float-charging and without requiring
the battery to discharge to the automatic re-charge
13
SC810
Applications Information (continued)
voltage. ENB should be held low for at least 1ms to ensure
a successful forced re-charge.
Forced re-charge can be requested at any time during the
charge cycle, or even with no charging source present,
with no detrimental effect on charger operation. This
allows the host processor to schedule a forced re-charge
at any desired interval, without regard to whether a charge
cycle is already in progress, or even whether a charging
source is present. Forced re-charge will neither assert nor
release the STATB output.
Status Output
The STATB pin is an open-drain output. It is asserted
(driven low) as charging begins after a valid charging
input is applied and the VIN pin is greater than the input
UVLO level and less than the OVP level. STATB is also
asserted as charging begins after the ENB input returns to
either of the enable voltage ranges (mid or low voltage)
from the disable (high voltage) range. STATB is subsequently released when the termination current is reached
to indicate end-of-charge, when the ENB input is driven
high to disable charging, or when the input voltage is
removed. If the battery is already fully charged when a
charge cycle is initiated, STATB is asserted, and remains
asserted for approximately 750μs before being released.
The STATB pin is not asserted for automatic re-charge
cycles.
battery reaches 4.2V and eventually the controller is
entirely in CV regulation. The soft transition effectively
reduces the charge current below that which is permitted
for a portion of the charge cycle, which increases charge
time.
In the SC810, a logical transition is implemented from CC
to CV to recover the charge current lost due to the soft
transition. The controller regulates only current until the
output voltage exceeds the transition threshold voltage.
It then switches to CV regulation. The transition voltage
from CC to CV regulation is typically 5mV higher than the
CV regulation voltage, which provides a sharp and clean
transition free of chatter between regulation modes. The
difference between the transition voltage and the regulation voltage is termed the CC/CV overshoot. While in CV
regulation, the output current sense remains active. If the
output current exceeds the programmed fast-charge
current by 5%, the controller reverts to current
regulation.
The logical transition from CC to CV results in the fastest
possible charging cycle that is compliant with the specified current and voltage limits of the Li-ion cell. The output
current is constant at the CC limit, then decreases abruptly
when the output voltage steps from the overshoot voltage
to the regulation voltage at the transition to CV control.
Thermal Limiting
The STATB pin may be connected to an interrupt input to
notify a host controller of the charging status or it can be
used as an LED driver.
Logical CC-to-CV Transition
The SC810 differs from monolithic linear single cell Li-ion
chargers that implement a linear transition from CC to CV
regulation. The linear transition method uses two simultaneous feedback signals — output voltage and output
current — to the closed-loop controller. When the output
voltage is sufficiently below the CV regulation voltage, the
influence of the voltage feedback is negligible and the
output current is regulated to the desired current. As the
battery voltage approaches the CV regulation voltage
(4.2V), the voltage feedback signal begins to influence the
control loop, which causes the output current to decrease
although the output voltage has not reached 4.2V. The
output voltage limit dominates the controller when the
Device thermal limiting is the third output constraint of
the CC/CV/TL control. This feature permits a higher input
OVP threshold, and thus the use of higher voltage or
poorly regulated adapters. If high input voltage results in
excessive power dissipation, the output current is reduced
to prevent overheating of the SC810. The thermal limiting
controller reduces the output current by iT ≈ –50mA/ºC for
any junction temperature TJ > T TL.
When thermal limiting is inactive,
TJ = TA + VΔ IFQ θJA,
where VΔ is the voltage difference between the VIN pin
and the BAT pin. However, if TJ computed this way exceeds
T TL, then thermal limiting will become active and the
thermal limiting regulation junction temperature will be
14
SC810
Applications Information (continued)
TJTL = TA + VΔ I(TJTL) θJA,
where
I(TJTL) = IFQ + iT (TJTL − T TL).
(Note that iT is a negative quantity.) Combining these two
equations and solving for TJTL, the steady state junction
temperature during active thermal limiting is
TJTL
TA V' IFQ iT TTL T JA
1 V' iT T JA
Although the thermal limiting controller is able to reduce
output current to zero, this does not happen in practice.
Output current is reduced to I(TJTL), reducing power dissipation such that die temperature equilibrium TJTL is
reached.
While thermal limiting is active, all charger functions
remain active and the charger logical state is preserved.
The low UVLO falling threshold ( VT UVLO-F) permits the
adapter voltage to be pulled down to just above the
battery voltage by the charging load whenever the
adapter current limit is less than the programmed fastcharge current. The SC810 should be operated with
adapter voltage below the rising selection threshold
(VTUVLO-R) only if the low input voltage is the result of
adapter current limiting. This implies that the VIN pin first
exceeds VTUVLO-R to begin charging, and is subsequently
pulled down to just above the battery voltage by the
charging load.
Interaction of Thermal Limiting and Current Limited
Adapter Charging
To permit the charge current to be limited by the adapter,
it is necessary that the fast-charge current be programmed
greater than the maximum adapter current, (IAD-LIM). In this
configuration, the CC regulator will operate with its pass
device fully on (in saturation, also called “dropout”). The
voltage drop from VIN to BAT is determined by the product
of the minimum RDS-ON of the pass device multiplied by the
adapter supply current.
Operating a Charging Adapter in Current Limit
In high charging current applications, charger power dissipation can be greatly reduced by operating the charging
adapter in current limit. The SC810 supports adaptercurrent-limited charging with a low UVLO falling threshold
and with internal circuitry designed for low input voltage
operation. To operate an adapter in current limit, RIPRGM is
chosen such that the programmed fast-charge current IFQ
exceeds the current limit of the charging adapter IAD-LIM.
Note that if IAD-LIM is less than 20% of IFQ, then the adapter
voltage can be pulled down to the battery voltage while
the battery voltage is below the pre-charge threshold. In
this case, care must be taken to ensure that the adapter
will maintain its current limit below 20% of IFQ at least until
the battery voltage exceeds the pre-charge threshold.
Failure to do so could permit charge current to exceed the
pre-charge current while the battery voltage is below the
pre-charge threshold. This happens because the low
input voltage will also compress the pre-charge threshold
internal reference voltage to below the battery voltage.
This will prematurely advance the charger logic from precharge current regulation to fast-charge regulation, and
the charge current will exceed the safe level recommended for pre-charge conditioning.
In dropout, the power dissipation in the SC810 is
PILIM = (minimum RDS-ON) x (IAD-LIM)2. Since minimum RDS-ON
does not vary with battery voltage, dropout power dissipation is constant throughout the CC portion of the
charge cycle while the adapter remains in current limit.
The SC810 junction temperature will rise above ambient
by PILIM x θJA. If the device temperature rises to the temperature at which the TL control loop limits charging
current (rather than the current being limited by the
adapter), the input voltage will rise to the adapter regulation voltage. The power dissipation will increase so that
the TL regulation will further limit charge current. This will
keep the adapter in voltage regulation for the remainder
of the charge cycle. In this case, the SC810 will continue
to charge with thermal limiting until charge current
decreases while in CV regulation (reducing power dissipation sufficiently). This results in a slow charge cycle, but
with no other negative effect.
To ensure that the adapter remains in current limit, the
internal device temperature must not rise to T TL. This
implies that θJA must be kept small enough, through
careful layout, to ensure that TJ = TA + (PILIM × θJA) < T TL.
15
SC810
Applications Information (continued)
Input Over-Voltage Protection
Short Circuit Protection
The VIN pin is protected from over-voltage to at least 30V
above GND. When the input voltage exceeds the OverVoltage Protection (OVP) rising threshold (VTOVP-R), charging is halted. When the input voltage falls below the OVP
falling threshold (VTOVP-F), charging resumes. An OVP fault
turns off the STATB output. STATB is turned on again when
charging restarts.
The SC810 can tolerate a BAT pin short circuit to ground
indefinitely. The current into a ground short (while
VBAT < 1.8V) is approximately 10mA. For VBAT > 1.8V, normal
pre-charge current regulation is active.
The OVP threshold has been set relatively high to permit
the use of poorly regulated adapters. Such adapters may
output a high voltage until loaded by the charger. A
too-low OVP threshold could prevent the charger from
ever turning on and loading the adapter to a lower voltage.
If the adapter voltage remains high despite the charging
load, the fast thermal limiting feature will immediately
reduce the charging current to prevent overheating of the
SC810. This behavior is illustrated in Figure 4, in which VBAT
= 3.0V, IFQ = 700mA, and VVIN is stepped from 0V to 8.1V.
Initially, power dissipation in the SC810 is 3.6W.
A short circuit or too little programming resistance to
ground on the IPRGM pin (<< 2.05kΩ) will prevent proper
regulation of the BAT pin output current. Prior to enabling
the output a check of the IPRGM pin is performed to
ensure that there is sufficient resistance to ground. A test
current is output on the IPRGM pin. If the test current
produces a voltage of sufficient amplitude, then the
output is enabled. An example with RIPRGM = 2.94kΩ is
illustrated in Figure 5, in which the test current is applied
for approximately 250μs to determine that there is no pin
short. If a short is detected, the test current persists until
the short to ground is removed, and then the charging
startup sequence will continue normally.
VVIN=8.1V, VBAT=3.0V
IBAT=700mA (Initially), PDISSIPATION=3.6W (Initially)
VIPRGM (1V/div)
IBAT (100mA/div)
VIPRGM=0V—
VVIN (2V/div)
IBAT (500mA/div)
IBAT=0mA—
VVIN (5V/div)
VBAT (2V/div)
VVIN =0V—
VVIN ,VBAT=0V—
400μs/div
IBAT=0mA—
1s/div
Figure 4 — Thermal Limiting Example
Notice the BAT output current is rapidly reduced to limit
the internal die temperature, then continues to decline as
the circuit board gradually heats up, further reducing the
conduction of heat from the die to the ambient environment. The fast thermal limiting feature ensures compliance with CCSA YD/T 1591-2006, Telecommunication
Industrial Standard of the People’s Republic of China —
Technical Requirements and Test Method of Charger and
Interface for Mobile Telecommunication Terminal, Section
4.2.3.1.
Figure 5 — IPRGM Pin Short-to-Ground Test During
Startup
A short to ground applied to the IPRGM pin while charging will also be detected, by a different method. IPRGM
pin short-to-ground detection on the IPRGM pin forces
the SC810 into reset. When the IPRGM ground short is
removed, the charger begins normal operation automatically without input power cycling.
Over-Current Protection
Over-current protection is provided in all modes of operation, including CV regulation. The output current is limited
to either the programmed pre-charge current limit value
16
SC810
Applications Information (continued)
or the fast-charge current limit value, depending on the
voltage at the output.
this event. While unlikely to do any harm, this effect must
also be considered.
Operation Without a Battery
USB Dedicated Charger Compatibility
The SC810 can be operated as a 4.2V LDO regulator
without the battery present, for example, for factory
testing. If this use is anticipated, the total output capacitance, CBAT plus any other capacitors tied directly to BAT
pin network, should be at least 2.2μF but less than 22μF to
ensure stability in CV regulation. To operate the charger
without a battery, the ENB pin must be driven low or
grounded. The output current is limited by the programmed fast-charge current. The charger should not be
disabled (VENB > VIH) without a battery present.
The SC810 is well suited to the USB Charging Specification,
Revision 1.0, Dedicated Charger, Sections 3.5 and 4.1, due
to thermal limiting and its current-limited-supply charging behavior.
Dynamically Selectable Charge Current
The IPRGM resistance can be altered dynamically under
processor control by switching a second IPRGM pin resistor. When the higher current is required, the switch is
turned on, making the effective programming resistance
equal to the parallel combination of the two resistors. The
external circuit is illustrated in Figure 6.
IPRGM
4
RIPRGM_HI
Hi/Lo
Current Select
RIPRGM
Figure 6 — Dynamic selection of low and high charge
currents.
Note that the IPRGM pin resistor programs the fast-charge,
pre-charge, and termination currents, so all will be modified by a change in the IPRGM pin resistor.
An open-drain GPIO can be used directly to engage the
parallel resistor RIPRGM_HI. Care must be taken to ensure that
the RDS-ON of the GPIO is considered in the selection of
RIPRGM_HI. Also important is the part-to-part and temperature variation of the GPIO RDS-ON, and their contribution to
the High Current charge current tolerance. Note also that
IPRGM will be pulled up briefly to as high as 3V during
startup to check for an IPRGM static pinshort to ground. A
small amount of current could, potentially, flow from
IPRGM into the GPIO ESD structure through RIPRGM_HI during
The USB Dedicated Charger is required to limit its output
current to more than 0.5A and less than 1.5A. A dedicated
charger identifies itself by shorting together the USB D+
and D- lines. Once the dedicated charger is detected, the
SC810, with its 1A maximum programmed fast charge
current, permits the fast-charge current to be set higher
than the 500mA USB High Power Mode specified limit to
permit faster charging of a large battery. (See the section
Dynamically Selectable Charge Current.)
If the USB Dedicated Charger’s current limit exceeds the
SC810 programmed fast-charge current, then its output
will regulate to 5V, and the fast-charge current will be
determined by the SC810 IPRGM pin resistance to ground.
If the resulting power dissipation in the SC810 causes an
excessive rise in temperature, then thermal limiting will
reduce the charge current as needed to ensure safe charging. But if the USB Dedicated charger’s current limit is less
than the SC810 programmed fast-charge current, then its
output voltage will be pulled down to the battery voltage
plus charging path dropout. (The USB Dedicated Charger
is required to maintain its current limit down to 2V.) This
behavior is recognized in the USB Battery Charging
Specification, Section 3.5, as an accepted means to reduce
power dissipation in the charging circuit while charging at
high current.
The SC810 thermal limiting and current-limited-adapter
charging capability together ensure reliable charging at
any programmed charge current, using any USB Battery
Charging Specification compliant Dedicated Charger,
regardless of its current limit.
External Power Path Management
Some applications require that the battery be isolated
from the load while charging. Figure 7 illustrates a typical
charger bypass circuit. This circuit powers the load directly
from the charging source via the Schottky diode DBYPASS.
17
SC810
Applications Information (continued)
DBYPASS
Opt.
QISO
RISO_PD
SC810
VADAPTER/USB
2.2μF
VIN
ENB
STATB
BAT
GND
Device
Load
RIPRGM
IPRGM
2.2μF
Figure 7 — Battery Isolation and Power Path Bypass, Powering the Load Directly From the Charging Adapter
When the charging source is present, the p-channel
MOSFET battery isolation switch Q ISO source-to-gate
voltage VSG is equal to minus the DBYPASS forward-biased
voltage drop, ensuring that the switch QISO is off (open).
When the charging source is removed, the MOSFET gate is
pulled down to ground by RISO_PD, closing the battery isolation switch and connecting the battery to the load.
When the charging source is removed, the turn-on of QISO
could be delayed due to its gate capacitance. If so, the
substrate PN diode of QISO will become forward biased,
holding the load voltage to within 0.7V of the battery
voltage until VSG > V TH, turning on QISO. This momentary
voltage drop can be mitigated by the use of an optional
Schottky diode in parallel with QISO, as shown.
With the load isolated from the battery, the charging
adapter must supply both the load current and the charging current. If the sum of these should ever exceed the
current capacity of the adapter, VADAPTER will be pulled
down. Current limited adapter operation of the SC810
ensures charge cycle integrity if the device load pulls the
adapter voltage down to the battery voltage plus charger
dropout voltage at the CC current, or even deeper into
dropout if necessary to further reduce the charge current
to power the device load.
To better understand the trade-offs between charger
bypass and direct connection of the load to the battery,
see the Semtech Application Note AN–PM–0802, Tradeoffs
Between Direct Battery Connection vs. Bypassing the
Charger.
Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and
X7R dielectric material types are recommended. The BAT
pin capacitor should be at least 1μF, but can be as large as
desired to accommodate the required input capacitors of
regulators connected directly to the battery terminal. BAT
pin total capacitance must be limited if the SC810 is to be
operated without the battery present. See the section
Operation Without a Battery. The VIN pin capacitor is typically between 0.1μF and 2.2μF, although larger values will
not degrade performance. Capacitance must be evaluated at the expected bias voltage (4.2V for the BAT pin
capacitor, the expected VVIN supply regulation voltage for
the VIN pin capacitor), rather than the zero-volt capacitance rating.
PCB Layout Considerations
Layout for linear devices is not as critical as for a switching
regulator. However, careful attention to detail will ensure
reliable operation.
ƒ
ƒ
ƒ
Place input and output capacitors close to
the device for optimal transient response
and device behavior.
Connect all ground connections directly
to the ground plane. If there is no ground
plane, connect to a common local ground
point before connecting to board ground
near the GND pin.
Attaching the part to a larger copper
footprint will enable better heat transfer
from the device, especially on PCBs with
internal ground and power planes.
18
SC810
Outline Drawing — MLPD-UT6 2x2
A
D
B
DIM
E
PIN 1
INDICATOR
(LASER MARK)
A2
A
SEATING
PLANE
aaa C
C
A
A1
A2
b
D
D1
E
E1
e
L
N
aaa
bbb
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
.024
.002
(.006)
.007 .010 .012
.075 .079 .083
.061 .067 .071
.075 .079 .083
.026 .031 .035
.020 BSC
.010 .014 .018
6
.003
.004
.020
.000
0.60
0.05
(0.152)
0.18 0.25 0.30
1.90 2.00 2.10
1.55 1.70 1.80
1.90 2.00 2.10
0.65 0.80 0.90
0.50 BSC
0.25 0.35 0.45
6
0.08
0.10
0.50
0.00
A1
D1
2
1
LxN
E1
N
bxN
e
bbb
C A B
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.
19
SC810
Land Pattern — MLPD-UT6 2x2
H
R
DIM
(C)
G
K
Y
P
Z
C
G
H
K
P
R
X
Y
Z
DIMENSIONS
INCHES
MILLIMETERS
(.077)
.047
.067
.031
.020
.006
.012
.030
.106
(1.95)
1.20
1.70
0.80
0.50
0.15
0.30
0.75
2.70
X
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
3.
THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805) 498-2111 Fax: (805) 498-3804
www.semtech.com
20
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