SC813 [SEMTECH]
Adapter/USB Tri-Mode Single-cell Li-ion Charger; 适配器/ USB三模式单节锂离子电池充电器
| 型号： | SC813 |
| 厂家： | 
SEMTECH CORPORATION |
| 描述： | Adapter/USB Tri-Mode Single-cell Li-ion Charger |
| 文件： | 总23页 (文件大小：374K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SC811 / SC813
Adapter/USB Tri-Mode
Single-cell Li-ion Charger
POWER MANAGEMENT
Features
Description
The SC811 and SC813 are highly versatile single input
triple mode (adapter/USB high current, USB low current)
linear single-cell Li-ion battery chargers, each in an 8 lead
2x2 MLPD ultra-thin package. The input will survive sus-
tained input voltage up to 30V to protect against hot plug
overshoot and faulty charging adapters. The SC811 has
9.6V rising, 8.2V falling OVP thresholds for general purpose
charging with low cost adaptors. The SC813 has 6V rising,
5.6V falling OVP thresholds for customers utilizing charg-
ing adapters with specifications that are similar to a USB
Vbus supply. The SC811 and SC813 differ only in OVP
threshold.
Single input charger with three charging modes
Constant voltage — 4.2V, 1% regulation
Fast-charge current regulation — 15% at 70mA,
9% at 700mA
Charging by current regulation, voltage regulation,
and thermal limiting
Input voltage protection — 30V
Current-limited adapter support capability — reduces
power dissipation in charger IC
USB high and low power modes limit charge current
to prevent USB Vbus overload
Instantaneous CC-to-CV transition for faster charging
Programmable battery-dependent currents (adapter
mode fast- and pre-charge, termination)
Programmable source-limited currents (USB-high
mode fast-charge, and USB-low mode fast- and
pre-charge)
Charging begins automatically when an input source is
applied to the charging input. Thermal limiting protects
against excessive power dissipation. The charger can be
programmed to turn off when charging is complete or to
continue operating as an LDO regulator while float-charg-
ing the battery.
Independent programming of termination current
with dual-mode operation
Three charging modes are provided: adapter mode, USB
low power mode, and USB high power mode. Battery-
capacity-dependent and charging source-dependent
current programming are independently programmed.
Adapter and USB high power modes can charge up to 1A,
with the charging adapter operating either in voltage
regulation or in current limit to obtain the lowest possible
power dissipation. A single current programming pin is
used to program pre-charge, termination, and adapter-
mode fast-charge currents in fixed proportions. In the
USB modes, a second programming pin is used to program
low power pre-charge current and low and high power
fast-charge currents. This configuration allows indepen-
dent programming of termination current. The two USB
modes dynamically limit the charging load if necessary to
prevent overloading the USB Vbus supply.
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 or USB load transients
High operating voltage range of SC811 permits use
of unregulated adapters
Complies with CCSA YD/T 1591-2006
Space saving 2x2x0.6 (mm) MLPD package
WEEE and RoHS compliant
Applications
Mobile phones
MP3 players
GPS handheld receivers
Typical Application Circuit
SC811 / SC813
Battery Device
Pack Load
VADAPTER
VIN
ENB
BAT
MODE SELECT
MODE
STATB
GND
2.2 μF
IPRGM
IPUSB
2.2 μF
April 7, 2008
© 2008 Semtech Corporation
1
SC811 / SC813
Pin Configuration
Ordering Information
Device
Package
SC811ULTRT(1)(2)
SC813ULTRT(1)(2)
SC811EVB
MLPD-UT-8 2×2
MLPD-UT-8 2×2
Evaluation Board
Evaluation Board
VIN
MODE
STATB
GND
ENB
1
2
3
4
8
7
6
5
TOP VIEW
SC813EVB
BAT
Notes:
(1) Available in tape and reel only. A reel contains 3,000 devices.
(2) Lead-free package only. Device is WEEE and RoHS compliant.
IPRGM
IPUSB
T
MLPD-UT8; 2x2, 8 LEAD
θJA = 68°C/W
Marking Information
81x
yw
x = 1 or 3
yw = Date Code
2
© 2008 Semtech Corporation
SC811 / SC813
Absolute Maximum Ratings
Recommended Operating Conditions
VIN (V). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +30.0
BAT, IPRGM, IPUSB (V) . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.5
STATB, ENB, MODE (V) . . . . . . . . . . . . . . . . . . . -0.3 to VBAT + 0.3
VIN Input Current (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5
Total Power Dissipation (W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
BAT, IPRGM, IPUSB Short to GND Duration. . . . Continuous
ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Operating Ambient Temperature (°C) . . . . . . . . . -40 to +85
SC811:
VIN Adapter Mode Operating Voltage(2) (V). . . 4.60 to 8.20
VIN USB Modes Operating Voltage(2) (V). . . . . . 4.35 to 8.20
SC813:
VIN Adapter Mode Operating Voltage(2) (V). . . 4.60 to 5.60
VIN USB Modes Operating Voltage(2) (V). . . . . . 4.35 to 5.60
Thermal Information
Thermal Resistance, Junction to Ambient(3) (°C/W). . . . . 68
Junction Temperature Range (°C) . . . . . . . . . . . . . . . . . . +150
Storage Temperature Range (°C). . . . . . . . . . . . -65 to +150
Peak IR Reflow Temperature (°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-A114-B.
(2) This is the input voltage at which the charger is guaranteed to begin operation. 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; VBAT = 3.7V; Typ values at 25°C; Min and Max at -40°C < TA < 85°C, unless specified.
Parameter
Symbol
VTADUVLO-R
VTADUVLO-F
VTUSBUVLO-R
VTUSBUVLO-F
VTUSBUVLO-H
Conditions
Min
4.30
2.70
Typ
4.45
2.85
4.20
4.00
Max
4.60
3.00
4.35
Units
VIN Adapter Mode Rising Threshold
VIN Adapter Mode Falling Threshold(1)
VIN USB Modes Rising Threshold
VIN USB Modes Falling Threshold
VIN USB Modes Hysteresis
V
V
VVIN > VBAT
VVIN > VBAT
V
VVIN > VBAT
3.65
100
V
VTUSBUVLOR - VTUSBUVLOF
All modes, SC811
mV
9.0
5.85
8.8
9.6
6.0
VIN OVP Rising Threshold
VIN OVP Falling Threshold
VIN OVP Hysteresis
VTOVP-R
VTOVP-F
VTOVP-H
V
V
All modes, SC813
All modes, SC811
8.2
5.6
50
All modes, SC813
5.75
200
100
VTOVP-R - VTOVP-F , all modes, SC811
VTOVP-R - VTOVP-F , all modes, SC813
mV
50
3
© 2008 Semtech Corporation
SC811 / SC813
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
Min
Typ
Max
Units
VIN Charging Disabled Quiescent
Current
IqVIN_DIS
VENB = VBAT
2
3
mA
VIN Charging Enabled Quiescent
Current
VENB = 0V,
excluding IBAT, IIPRGM, and IIPUSB
IqVIN_EN
VCV
2
3
mA
V
CV Regulation Voltage
IBAT = 50mA, -40°C ≤ TJ ≤ 125°C
4.16
-20
4.20
4.24
10
Relative to VCV @ 50mA,
CV Voltage Load Regulation
VCV_LOAD
mV
1mA ≤ IBAT ≤ 1A, -40°C ≤ TJ ≤ 125°C
Re-charge Threshold
VTReQ
VTPreQ
lBAT_V0
lBAT_DIS
VCV - VBAT
60
100
2.90
0.1
140
2.95
1
mV
V
Pre-charge Threshold (rising)
2.85
VBAT = VCV, VVIN = 0V
μA
μA
VBAT = VCV, VVIN = 5V, VENB = 2V
0.1
1
Battery Leakage Current
VBAT = VCV, VVIN = 5V;
ENB not connected
lBAT_MON
0.1
1
μA
IPRGM Programming Resistor
RIPRGM
IFQ_AD
2.05
643
29.4
745
kΩ
Fast-Charge Current, Adapter Mode
RIPRGM = 2.94kꢀ, VTPreQ < VBAT < VCV
RIPRGM = 2.94kꢀ, 1.8V < VBAT < VTPreQ
RIPRGM = 2.94kꢀ, VBAT = VCV
694
139
69
mA
Pre-Charge Current, Adapter Mode and
USB High Power Mode
IPreQ_AD
105
173
mA
Termination Current, Any Mode
IPUSB Programming Resistor
ITERM
59
80
mA
kΩ
RIPUSB
2.05
29.4
Fast-Charge Current, USB High Power
Mode
IFQ_USB
RIPUSB = 4.42kꢀ, 1.8V < VBAT < VTPreQ
RIPUSB = 4.42kꢀ, 1.8V < VBAT < VCV
427
69
462
92
497
mA
mA
Pre-Charge Current and Fast-Charge
Current, USB Low Power Mode
IPreQ_USB
116
Dropout Voltage
VDO
IBAT = 700mA, 0°C ≤ TJ ≤125°C
VVIN = 5.0V, VTPreQ < VBAT < VCV
1.8V < VBAT < VTPreQ
0.40
2.04
0.60
V
V
V
IPRGM Fast-charge Regulated Voltage
IPRGM Pre-charge Regulated Voltage
VIPRGM_FQ
VIPRGM_PQ
VTIPRGM_TERM
VIPUSB_FQ
0.408
VBAT = VCV
(either input selected)
IPRGM Termination Threshold Voltage
IPUSB Fast-charge Regulated Voltage
0.204
2.04
V
V
V
VVIN = 0V, VTPreQ < VBAT < VCV
VVIN = 0V, VBAT < VTPreQ
IPUSB Pre-charge or USB Low Power
Mode Regulated Voltage
VIPUSB_PQ
0.408
5mA ≤ VIN supply current limit ≤
500mA, VMODE = 2V,
VIN USB Modes Under-Voltage Load
Regulation Limiting Voltage
VUVLR
4.45
4.58
4.70
V
RIPUSB = 3.65kꢀ (559mA)
4
© 2008 Semtech Corporation
SC811 / SC813
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
Min
Typ
130
50
Max
Units
Thermal Limiting Threshold
Temperature
TTL
iT
°C
Thermal Limiting Rate
mA/ °C
ENB or MODE Input High Voltage
Threshold
VIH
VIM
VIL
1.6
0.7
V
V
V
ENB or MODE Input Mid Voltage Range
1.3
0.3
ENB or MODE Input Low Voltage
Threshold
ENB Input High-range Threshold Input
Current
ENB current required to pull ENB from
floating midrange into high range
IENB_IH_TH
23
50
1
μA
μA
Current required to hold ENB in
ENB Input High-range Sustain Input
Current
IENB_IH_SUS
high range, Min VIH ≤ VENB ≤ VBAT
,
0.3
23
Min VIH ≤ VBAT ≤ 4.2V
MODE Input High-range Input Current
IMODE_IH
IIM
VMODE = Min VIH
75
5
μA
μA
ENB or MODE Input Mid-range Load
Limit
Input will float to mid range when this
load limit is observed.
-5
ENB or MODE Input Low-range Input
Current
IIL
0V ≤ (VENB or VMODE) ≤ Max VIL
VMODE = VBAT = 4.2V,
-25
12
μA
μA
μA
MODE Input Monitor State Input
Current
IMODE_MON
IILEAK
VSTAT_LO
ISTAT_HI
1
1
V
ENB = 1V and Charging Terminated
VVIN = 0V or VVIN = 5V,
ENB or MODE Input Leakage
STATB Output Low Voltage
VENB and VMODE = VBAT = 4.2V
ISTAT_SINK = 2mA
0.5
1
V
STATB Output High Current
Notes:
VSTAT = 5V
μA
(1) Sustained operation to VTADUVLO-F ≤ VVIN is guaranteed only if a current limited charging source applied to VIN is pulled below VTADUVLO-R by the
charging load; forced VIN voltage below VTADUVLO-R may in some cases result in regulation errors or other unexpected behavior.
5
© 2008 Semtech Corporation
SC811 / SC813
Typical Characteristics
CV Line Regulation
CV Load Regulation
TA = 25οC, VVIN = 5V
TA = 25οC, IBAT = 50mA
4.204
4.2
4.204
4.2
4.196
4.192
4.188
4.184
4.18
4.196
4.192
4.188
4.184
4.18
0
100
200
300
400
500
600
700
800
5
5.5
6
6.5
7
7.5
8
IBAT (mA)
VVIN (V)
CV Temperature Regulation
VVIN = 5V, IBAT = 50mA
CC AD or USB High FQ Line Regulation
TA = 25οC, VBAT = 3.7V
4.204
4.2
720
680
640
600
560
520
480
440
Ω
RIPRGM or RIPUSB = 2.94k
4.196
4.192
4.188
4.184
4.18
Ω
RIPRGM or RIPUSB = 4.42k
-40
-20
0
20
40
60
80
100
120
4.5
5
5.5
6
6.5
VVIN (V)
7
7.5
8
Ambient Temperature (oC)
CC AD or USB High FQ VBAT Regulation
CC AD or USB High FQ Temperature Regulation
TA = 25οC, VVIN = 5V
VVIN = 5V, VBAT = 3.7V
720
680
640
600
560
520
480
440
720
680
640
600
560
520
480
440
Ω
RIPRGM or RIPUSB = 2.94k
Ω
RIPRGM or RIPUSB = 2.94k
Ω
RIPRGM or RIPUSB = 4.42k
Ω
RIPRGM or RIPUSB = 4.42k
2.9
3.1
3.3
3.5
3.7
3.9
4.1
-40
-20
0
20
40
60
80
100
120
Ambient Temperature (oC)
VBAT (V)
6
© 2008 Semtech Corporation
SC811 / SC813
Typical Characteristics
CC PQ Line Regulation
CC PQ Temperature Regulation
VVIN = 5V, VBAT = 2.6V
TA = 25οC, VBAT = 2.6V
160
150
140
130
120
110
100
90
160
150
140
130
120
110
100
90
Ω
RIPRGM or RIPUSB = 2.94k
Ω
RIPRGM or RIPUSB = 2.94k
Ω
RIPRGM or RIPUSB = 4.42k
Ω
RIPRGM or RIPUSB = 4.42k
-40
-20
0
20
40
60
80
100
120
5
5.5
6
6.5
7
7.5
8
Ambient Temperature (oC)
VVIN (V)
CC USB Low Power FQ Line Regulation
CC USB Low Power FQ VBAT Regulation
TA = 25οC, VVIN = 5V
TA = 25οC, VBAT = 3.7V
160
150
140
130
120
110
100
90
160
150
140
130
120
110
100
90
Ω
Ω
RIPUSB = 2.94k
RIPUSB = 2.94k
Ω
Ω
RIPUSB = 4.42k
RIPUSB = 4.42k
2.9
3.1
3.3
3.5
VBAT (V)
3.7
3.9
4.1
4.5
5
5.5
6
6.5
VVIN (V)
7
7.5
8
CC USB Low Power FQ Temperature Regulation
VVIN = 5V, VBAT = 3.7V
160
150
Ω
RIPUSB = 2.94k
140
130
120
110
100
90
Ω
RIPUSB = 4.42k
-40
-20
0
20
40
60
80
100
120
Ambient Temperature (oC)
7
© 2008 Semtech Corporation
SC811 / SC813
Typical Characteristics
IFQ_AD vs. RIPRGM , or IFQ_USB High Power vs. RIPUSB
IPQ_AD or IPQ_USB vs. RIPRGM, or IFQ_USB Low Power vs. RIPUSB
VVIN = 5V, VBAT = 3.7V, TA = 25οC
VVIN = 5V, VBAT = 2.6V, TA = 25οC
1000
800
600
400
200
0
200
160
120
80
40
0
2
6
10
14
18
22
26
30
2
6
10
14
18
22
26
30
Ω
Ω
)
RIPRGM or RIPUSB (k
)
RIPRGM or RIPUSB (k
Charging Cycle Battery Voltage and Current
Pre-Charging Battery Voltage and Current
850mAhr battery, RIPRGM = 2.94k , VVIN = 5.0V, TA = 25οC
850mAhr battery, RIPRGM = 2.94k , VVIN = 5.0V, TA = 25οC
Ω
Ω
4
3.75
3.5
3.25
3
800
700
600
500
400
300
200
100
0
7
6
5
4
3
2
1
0
700
600
500
400
300
200
100
0
IBAT
VBAT
VBAT
2.75
2.5
2.25
2
IBAT
0
2
4
6
8
10
12
14
16
18
20
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
Time (s)
Time (hrs)
CC-to-CV Battery Voltage and Current
Re-Charge Cycle Battery Voltage and Current
850mAhr battery, RIPRGM = 2.94k , VVIN = 5.0V, TA = 25οC
Ω
Ω
850mAhr battery, RIPRGM = 2.94k , VVIN = 5.0V, Load = 10mA
4.21
4.2
710
690
670
650
630
610
4.5
450
400
350
300
250
200
150
100
50
4
3.5
3
VBAT
IBAT
4.19
4.18
4.17
4.16
2.5
2
VBAT
1.5
1
IBAT
0.5
Discharge hours 2 - 6 omitted.
1.0 1.5 2/6
Time (hrs)
0
0
44
44.5
45
45.5
46
46.5
47
47.5
48
0.0
0.5
6.5
7.0
7.5
Time (min)
8
© 2008 Semtech Corporation
SC811 / SC813
Typical Characteristics
Mode Reselection — USB Low to USB High
Mode Reselection — USB High to USB Low
VVIN=5V, VBAT=3.7V
VVIN=5V, VBAT=3.7V
IBAT (100mA/div))
VMODE (2V/div)
V
MODE (2V/div)
V
MODE=0V—
IBAT (100mA/div)
BAT=0mA—
V
MODE=0V—
I
IBAT=0mA—
100μs/div
100μs/div
Mode Reselection — AD to USB High
Mode Reselection — USB High to AD
V
VIN=5V, VBAT=3.7V
VVIN=5V, VBAT=3.7V
IBAT (100mA/div)
IBAT (100mA/div)
VMODE (2V/div)
VMODE (2V/div)
V
MODE=0V—
VMODE=0V—
IBAT=0mA—
I
BAT=0mA—
100μs/div
100μs/div
Mode Reselection — USB Low to AD
VVIN=5V, VBAT=3.7V
Mode Reselection — AD to USB Low
V
VIN=5V, VBAT=3.7V
IBAT (100mA/div)
VMODE (2V/div)
V
MODE (2V/div)
MODE=0V—
V
VMODE=0V—
IBAT (100mA/div)
IBAT=0mA—
IBAT=0mA—
100μs/div
100μs/div
9
© 2008 Semtech Corporation
SC811 / SC813
Pin Descriptions
Pin #
Pin Name
Pin Function
Supply pin — connect to charging adapter (wall adapter or USB). This pin is protected against damage due to
high voltage up to 30V.
1
VIN
Charging mode selection (tri-level logical) input — Logical high selects USB high power mode, floating selects
USB low power mode, ground selects adapter mode.
2
MODE
Status output pin — This open-drain pin is asserted (pulled low) when a valid charging supply is connected to
the VIN pin, 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
4
STATB
GND
Ground
Fast-charge and pre-charge current programming pin for a USB mode charging source — USB high power mode
(100%) and low power mode (20%) fast-charge current are programmed by connecting a resistor from this pin to
ground. USB low power mode pre-charge current is equal to the low power mode fast-charge current (20% of USB
high power mode fast-charge current).
5
6
IPUSB
Adapter mode fast-charge, adapter and USB high power modes pre-charge, and all modes termination current
programming pin — Connect a resistor from this pin to ground. Pre-charge current is 20% of IPRGM-programmed
adapter mode fast-charge current when in adapter mode or USB high power mode. The charging termination
current threshold (for adapter or either USB mode selection) is 10% of the IPRGM programmed fast-charge current.
IPRGM
7
8
BAT
ENB
Charger output — connect to battery positive terminal.
Combined device enable/disable — Logic high disables the device. Tie 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 SC811/3 is to be operated without a battery connected to BAT.
Pad is for heatsinking purposes — not connected internally. Connect exposed pad to ground plane using
multiple vias.
T
Thermal Pad
10
© 2008 Semtech Corporation
SC811 / SC813
Block Diagram
2
V_Adapter
or V_USB
MODE
VIN
1
1V
VTMODE_HIGH = ~1.50V
VTMODE_LOW = ~0.55
Tri-level
Control
Mode Selection Logic
Ad/USB select
(USB
only)
Regulated
System
Supply
VVUSB_UV_LIM = 4.575V
To
System
Load
V
CV = 4.2V
CV
BAT
7
CC
VIREF
Lithium-
Ion
Single
Cell
Battery
Pack
CC
Feedback
Selection
Die
Temperature
Thermal
Limiting
VT_CT
Precharg, CC/CV
& Termination
STATB
3
Termination
Controller, Logical
State Machine
VTIPRGM_TERM
VTENB_HIGH = ~1.50V
VTENB_LOW = ~0.55
Tri-level
Control
1V
ENB
IPUSB
RIPUSB
IPRGM
RIPRGM
GND
8
5
6
4
11
© 2008 Semtech Corporation
SC811 / SC813
Applications Information
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). 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.
Charger Operation
The SC811/3 is a single input tri-mode stand-alone Li-ion
battery charger. (The SC811 differs from the SC813 only in
the input voltage Over Voltage Protection threshold.) It
provides selections of adapter mode and USB high and
low power mode charging. The device is independently
programmed for battery capacity dependent currents
(adapter fast-charge current and termination current)
using the IPRGM pin. Charging currents from the USB
Vbus supply, which has a maximum load specification, are
programmed using the IPUSB pin when either of the USB
modes is selected.
Charging Input Pin Mode Dependencies
The UVLO rising and falling thresholds are adjusted with
the charging mode selected. In adapter mode, if the
charging current loads the adapter beyond its current
limit, the input voltage will be pulled down to just above
the battery voltage. The adapter mode UVLO falling
threshold is set close to the battery voltage pre-charge
threshold to permit low-dissipation charging from a
current limited adapter.
When an 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 IPRGM (adapter or USB high power
modes) or IPUSB (USB low power mode) programmed
fast-charge current.
The USB modes provide a higher UVLO falling threshold
applicable to the USB specification. The USB modes also
provide Under-Voltage Load Regulation (UVLR), in which
the charging current is reduced if needed to prevent
overloading of the USB Vbus supply. UVLR can serve as a
low-cost alternative to directly programming the USB
low power charge current. This can be beneficial for
charging small batteries, for which the USB high power
fast-charge current must be programmed to less than
500mA. The fixed 20% USB low power mode fast-charge
current would be less than 100mA and, therefore, is
unsuitable for minimum charge-time applications. UVLR
can also be used where there is no signal available to
indicate whether USB low or high power mode should be
selected.
When the battery voltage exceeds the pre-charge thresh-
old, typically within seconds for a standard battery with a
starting cell voltage greater than 2V, the fast-charge
Constant Current (CC) mode begins. The charge current
soft-starts in three steps (20%, 60%, and 100% of pro-
grammed fast-charge current) to reduce adapter load
transients. CC current is programmed by the IPRGM resis-
tance to ground when adapter mode is selected and by
the IPUSB resistance to ground when either USB mode is
selected. In USB low power mode, the CC current is held
at 20% of the IPUSB programmed fast-charge current.
The charger begins Constant Voltage (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 regardless of the
mode selected. This is known as charge termination.
All modes use the same input Over-Voltage Protection
(OVP) threshold as defined in the Electrical Characteristics
section for the device being used.
Constant Current Mode Fast-charge Current
Programming
Constant Current (CC) regulation is active when the
battery voltage is above VTPreQ and less than VCV. When
adapter mode is selected, the programmed CC regula-
tion fast-charge (FQ) current is inversely proportional to
Optional Float-charging or Monitoring
Depending on the state of the ENB input, upon termina-
tion the SC811/3 either operates indefinitely as a voltage
regulator (known as float-charging) or it turns off its
12
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
the resistance between IPRGM and GND according to the
equation
1a and 1b. Each figure shows the nominal fast-charge
current versus nominal RIPRGM or RIPUSB resistance as the
center plot, and two theoretical limit plots indicating
maximum and minimum current versus nominal pro-
gramming 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 resis-
tors. The dots on each plot indicate the currents obtained
with standard value 1% tolerance resistors. Figures 1a
and 1b show low and high resistance ranges, respectively.
The USB low power mode fast-charge current accuracy is
exactly like that of pre-charge in high power mode. USB
low power mode current regulation accuracy is addressed
in the next section.
9
,35*0 B 7\S
,
ꢁ
ꢀꢀꢁꢁꢁ ꢀ
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5,35*0
When either of the USB modes is selected, the pro-
grammed CC regulation fast-charge current is inversely
proportional to the resistance between IPUSB and GND
according to the equation
9
,386% B 7\S
,
ꢁ
ꢀꢀꢁꢁꢁ ꢀ
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5,386%
The fast-charge current can be programmed for a
minimum of 70mA and a maximum of 995mA for either
adapter or USB high power mode. This range for both
modes permits the use of USB high power mode for
general purpose adapter charging, allowing fully inde-
pendent programming of termination current. (See the
application sections, Independent Programming of
Termination Current, and USB-only Charging of Very
Large Batteries.)
Pre-charge and USB Low Power Mode Fast-
charge Current Regulation
Pre-charging is automatically selected when the battery
voltage is below the pre-charge threshold voltage (VTPreQ),
typically 2.8V. Pre-charge current conditions the battery
for fast charging. The pre-charge current value is fixed at
20% nominally of the fast-charge current. It is pro-
grammed by the resistance between IPRGM and GND for
adapter mode and USB high power mode, and by the
resistance between IPUSB and GND for USB low power
mode. Note that USB low power mode pre-charge current
is equal to USB low power mode fast-charge current.
Current regulation accuracy is dominated by gain error at
high current settings, and offset error at low current set-
tings. The range of expected fast-charge output current
versus programming resistance RIPRGM or RIPUSB (for adapter
or USB high power mode, respectively) is shown in Figures
1100
1050
1000
950
900
850
800
750
700
650
600
550
500
450
400
350
300
250
325
300
275
250
225
200
175
150
125
100
75
50
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Ω
RIPRGM or RIPUSB (k ), R-tol = 1%
Ω
RIPRGM or RIPUSB (k ), R-tol = 1%
Figure 1a — Fast-charge Current Tolerance versus
Programming Resistance, Low Resistance Range
Figure 1b — Fast-charge Current Tolerance versus
Programming Resistance, High Resistance Range
13
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
270
260
250
240
230
220
210
200
190
180
170
160
150
140
130
120
110
100
90
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
80
70
60
50
40
30
0
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Ω
Ω
RIPRGM or RIPUSB (k ), R-tol = 1%
RIPRGM or RIPUSB (k ), R-tol = 1%
Figure 2b — Pre-charge Current and USB Low Power
Mode Fast-charge Current Tolerance vs. Programming
Resistance, High Resistance Range
Figure 2a — Pre-charge Current and USB Low Power
Mode Fast-charge Current Tolerance vs. Programming
Resistance, Low Resistance Range
Pre-charge current regulation accuracy is dominated by
offset error. The range of expected pre-charge output
current versus programming resistance RIPRGM or RIPUSB is
shown in Figures 2a and 2b. Each figure shows the
nominal pre-charge current versus nominal RIPRGM or RIPUSB
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% toler-
ance resistors. The dots on each plot indicate the currents
obtained with standard value 1% tolerance resistors.
Figures 2a and 2b show low and high resistance ranges,
respectively.
The termination threshold current is fixed at 10% of the
adapter mode fast-charge current, as programmed by the
resistance between IPRGM and GND, for all charging
modes. If only the USB modes will be used, the termina-
tion threshold current can be programmed independently
of the fast-charge current. (See the application sections,
Independent Programming of Termination Current, and
USB-only Charging of Very Large Batteries.)
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 300ꢁs to 550ꢁs 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
When the battery voltage reaches VCV, the SC811/3 transi-
tions 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 termi-
nation threshold 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.
Termination threshold current accuracy is dominated by
offset error. The range of expected termination current
versus programming resistance RIPRGM (for any charging
mode) is shown in Figures 3a and 3b. Each figure shows
14
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
115
110
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
35
30
25
20
15
10
5
0
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
Ω
RIPRGM (k ), R-tol = 1%
Ω
RIPRGM (k ), R-tol = 1%
Figure 3b — Termination Current Tolerance vs.
Programming Resistance, High Resistance Range
Figure 3a — Termination Current Tolerance vs.
Programming Resistance, Low Resistance Range
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 GPIO, or a weak
pull-up or pull-down GPIO, configured as an input. The
driving GPIO must be able to sink or source at least 75μA
to ensure a low or high state, respectively, although the
drive current is typically far less. (See the Electrical
Characteristics table.)
the nominal termination current versus nominal RIPRGM
resistance as the center plot and two theoretical limit plots
indicating maximum and minimum current vs. 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 standard value 1% tolerance resistors.
Figures 3a and 3b show low and high resistance ranges,
respectively.
Mode Input
The MODE pin is a tri-level logical input. When driven high
(VMODE > Min VIH), the SC811/3 will operate in USB High
Power mode. If the MODE input voltage is within its speci-
fied mid range (Min VIM < VENB < Max VIM), either by floating
(by reconfiguring its GPIO as an input) or by being exter-
nally forced, the SC811/3 will operate in USB Low Power
mode. When driven low (VMODE < Max VIL), the SC811/3 will
operate in adapter mode.
Tri-level Logical Input Pins
The MODE and ENB pins are tri-level logical inputs. They
are designed to interface to a processor GPIO port that is
powered from a peripheral supply voltage as low as 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 or MODE low-range, and 1 to select high-
range. The GPIO port is configured as an input to select
mid-range.
When there is no charging source present, when the
charger is disabled, or when operating in the monitor
state (described in a later section), the MODE pin enters a
high impedance state, suspending the tri-level functional-
ity. Upon re-charge or re-enabling the charger, the MODE
pin tri-level interface is reactivated.
These pins can also be permanently grounded to select
low-range or left unconnected to select mid-range for
fixed mode operation. The MODE pin can also be perma-
nently connected to a logical high voltage source, such as
BAT or a regulated peripheral supply voltage.
Typically a processor GPIO port direction defaults to input
upon processor reset, or is high impedance when un-
powered. This is the ideal initial condition for driving the
MODE pin, since this will select USB Low Power mode,
The equivalent circuit looking into these pins is a variable
resistance, minimum 15kꢀ, to an approximately 1V source.
15
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
which is the safest default mode with the lowest fast-
charge current.
Note that if a GPIO with a weak pull-up input configura-
tion 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 — pos-
sibly 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 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, not from the battery.
Enable Input
The ENB pin is a tri-level logical input that allows selection
of the following behaviors:
• charging enabled with float-charging after ter-
mination (ENB = low range)
• charging enabled with float-charging disabled
and battery monitoring at termination (ENB =
mid range)
• charging disabled (ENB = high range).
If the ENB input voltage is permitted to float to mid-range,
the charger is enabled but it will turn off its output follow-
ing charge termination and will enter the monitor state.
This state is explained in the next section. Mid-range can
be selected either by floating the input (sourcing or
sinking less than 5ꢁA) or by being externally forced such
that VENB falls within the midrange limits specified in the
Electrical Characteristics table.
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 re-
charge cycle. The battery leakage current during monitor
state is no more than 1μA over temperature and typically
less than 0.1μA at room temperature.
When 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 fol-
lowing a previous termination, it will exit the monitor state
and begin float-charging.
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 SC811/3 can be forced
from the monitor state (no float-charging) directly to float-
charging 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 mid-
range, the charger will remain on only until the output
current becomes less than the termination current, and
charging terminates. The SC811/3 turns off its charging
output and returns to the monitor state within a millisec-
ond. 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 auto-
matic re-charge voltage. ENB should be held low for at
least 1ms to ensure a successful forced re-charge.
When 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 SC811/3 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.
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
16
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
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.
In the SC811/3, 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 regula-
tion voltage is termed the CC/CV overshoot. While in CV
regulation, the output current sense remains active. If the
output current exceeds by 5% the mode-dependent pro-
grammed fast-charge current, the controller reverts to
current regulation.
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 voltage is greater than the
UVLO level and less than the OVP level of the selected
mode. 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 will remain asserted for approximately 750μs before
being released. The STATB pin is not asserted for auto-
matic re-charge cycles.
The logical transition from CC to CV results in the fastest
possible charging cycle that is compliant with the speci-
fied 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.
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.
Thermal Limiting
Device thermal limiting is the third output constraint of
the Constant Current, Constant Voltage, “Constant”
Temperature (CC/CV/CT) 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 SC811/3. The
thermal limiting controller reduces the output current by
iT ≈ 50mA/ºC for any junction temperature TJ > TTL.
Logical CC-to-CV Transition
The SC811/3 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 influ-
ence 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 battery reaches 4.2V and eventually the control-
ler 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.
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
TTL, then thermal limiting will become active and the
thermal limiting regulation junction temperature will be
T
JTL = TA + VΔ I(TJTL) θJA,
where
I(TJTL) = IFQ − iT (TJTL − TTL).
17
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
Combining these two equations and solving for TJTL, the
steady state junction temperature during active thermal
limiting is
charge current. The SC811/3 should be operated with
adapter voltage below the rising selection threshold
(VTADUVLO-R) only if the low input voltage is the result of
adapter current limiting. This implies that the VIN voltage
first exceeds VTADUVLO-R to begin charging and is subse-
quently pulled down to just above the battery voltage by
the charging load.
TA ꢅ Vꢆ
IFQ_ x ꢅ iTTTL
ꢄJA
TJTL
ꢁ
1ꢅ Vꢆ iT ꢄJA
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 dissi-
pation such that die temperature equilibrium TJTL is
reached.
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 adapter mode 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.
While thermal limiting is active, all charger functions
remain active and the charger logical state is preserved.
Operating a Charging Adapter in Current Limit
In high charging current applications, charger power dis-
sipation can be greatly reduced by operating the charging
adapter in current limit. The SC811/3 adapter mode sup-
ports adapter-current-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 adapter input
programmed fast-charge current IFQ_AD exceeds the current
In dropout, the power dissipation in the SC811/3 is
P
ILIM = (minimum RDS-ON) x (IAD-LIM)2. Since minimum RDS-ON
does not vary with battery voltage, dropout power dissi-
pation is constant throughout the CC portion of the
charge cycle while the adapter remains in current limit.
The SC811/3 junction temperature will rise above ambient
by PILIM x θJA. If the device temperature rises to the tem-
perature at which the thermal limiting 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 thermal limit regulation will further limit charge
current. This will keep the adapter in voltage regulation
for the remainder of the charge cycle.
limit of the charging adapter IAD-LIM
.
Note that if IAD-LIM is less than 20% of IFQ_AD, 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_AD at least
until the battery voltage exceeds the pre-charge thresh-
old. 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 is because the low input
voltage will also compress the pre-charge threshold inter-
nal reference voltage to below the battery voltage. This
will prematurely advance the charger logic from pre-
charge current regulation to fast-charge regulation, and
the charge current will exceed the safe level recom-
mended for pre-charge conditioning.
To ensure that the adapter remains in current limit, the
internal device temperature must never rise to TTL. This
implies that θJA must be kept small enough to ensure that
TJ = TA + (PILIM × θJA) < TTL.
Under-Voltage Load Regulation in USB Modes
VIN pin UVLR in either USB mode prevents the battery
charging current from overloading the USB Vbus network,
regardless of the programmed fast-charge value. When
USB High Power or USB Low Power mode is selected, the
SC811/3 monitors the input voltage (VVIN) and reduces the
charge current as necessary to keep VVIN at or above the
UVLR limit (VUVLR). UVLR operates like a fourth output con-
The low UVLO falling threshold (VTADUVLO-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 fast-
18
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
straint (along with CC, CV, and CT constraints), but it is
active only when one of the USB modes is selected.
The OVP threshold of the SC811 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 SC811. 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
SC811 is 3.6W.
In either of the USB modes, if the VIN voltage is externally
pulled below VUVLR, the UVLR feature will reduce the charg-
ing current to zero. This condition will not be interpreted
as termination and will not result in an end-of-charge indi-
cation. The STATB pin will remain asserted as if charging is
continuing. This behavior prevents repetitive indications
of end-of-charge alternating with start-of-charge in the
case that the external VIN load is removed or is
intermittent.
V
VIN=8.1V, VBAT=3.0V
USB High Power and Low Power Support
IBAT=700mA (Initially), PDISSIPATION=3.6W (Initially)
The USB specification restricts the load on the USB Vbus
power network to 100mA for low power devices and for
high power devices prior to granting permission for high
power operation. The specification restricts the Vbus load
to 500mA for high power devices after granting permis-
sion to operate as a high power device. A fixed 1:5 ratio of
low power to high power charging current is desirable for
charging batteries with maximum fast-charge current of
at least 500mA. For this application, the SC811/3 provides
fixed 1:5 current ratio low-to-high power mode support,
via the tri-level MODE input pin.
I
BAT (100mA/div)
VVIN (2V/div)
VBAT (2V/div)
V
VIN ,VBAT=0V—
IBAT=0mA—
1s/div
Figure 4 — SC811 Thermal Limiting Example
For batteries with maximum fast-charge current less than
500mA, a fixed 1:5 low/high power charge current ratio
will result in suboptimal charging in USB low power mode.
For example, a 250mAh battery will typically require a
fast-charge current of 250mA or less. A fixed 1:5 ratio for
USB low-to-high power charging current will unnecessar-
ily reduce charging current to 50mA, well below the
100mA permitted. In this case, it may be preferable to
program USB low-power fast-charge current by switching
an external programming resistor. See the section Design
Considerations — Small Battery.
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 environ-
ment. 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.
Alternatively, the SC813 is offered for users who want to
limit OVP to a guaranteed maximum of 6V. The SC811 and
SC813 are alike except for OVP threshold.
Input Over-Voltage Protection
The VIN pin is protected from over-voltage to at least 30V
above GND. When the input voltage exceeds the Over-
Voltage Protection (OVP) rising threshold (VTOVP-R),
charging is halted. When the input voltage falls below the
OVP falling threshold (VTOVP-F), charging restarts. An OVP
fault turns off the STATB output. STATB is turned on again
when charging restarts.
Short Circuit Protection
The SC811/3 can tolerate a BAT pin short circuit to ground
indefinitely. The current into a ground short is approxi-
mately 10mA.
19
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
During charging, a short to ground applied to the active
current programming pin (IPRGM or IPUSB) is detected,
while a short to ground on the inactive programming pin
is ignored. Pin-short detection on an active current pro-
gramming pin forces the SC811/3 into reset, turning off
the output. A pin-short on either programming pin will
prevent startup regardless of the mode selected. When
the IPRGM or IPUSB pin-short condition is removed, the
charger begins normal operation automatically without
input power cycling.
• 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.
Design Considerations — Large Battery
A battery with a desired fast-charge current exceeding
500mA is most consistent with the USB fixed 1:5 current
ratio low-to-high power model of operation. For example,
consider an 800mAh battery, with maximum fast-charge
current of 800mA. The adapter input fast-charge should
be configured for 800mA max (RIPRGM = 2.80kΩ). Select
RIPUSB = 4.53kΩ to set USB high power fast-charge to
450mA, and the USB low power fast-charge set to
450/5 = 90mA. The MODE pin tri-level logical input can be
used to select between USB high power and USB low
power modes whenever a fixed 5:1 current ratio is
desired.
Over-Current Protection
Over-current protection is provided in all modes of opera-
tion, including CV regulation. The output current is limited
to either the programmed pre-charge current limit value
or the fast-charge current limit value, depending on the
voltage at the output.
Operation Without a Battery
The SC811/3 can be operated as a 4.2V LDO regulator
without the battery present, for example, factory testing.
If this use is anticipated, the output capacitance CBAT
should be at least 2.2ꢁF to ensure stability. To operate the
charger without a battery, the ENB pin must be driven low
or grounded.
Design Considerations — Small Battery
A battery with a desired fast-charge current less than
500mA will not be charged in minimum charge time when
in USB low power mode of operation with a 1:5 low-to-
high power mode current ratio. A 300mAh battery can be
used as an example with maximum fast-charge current of
300mA. In this example, the adapter input and USB input
high power fast-charge currents should both be set to
300mA. The USB low power fast-charge current of, for
example, 90mA, for a low-to-high power current ratio of
1:3.3, would provide a shorter charge time than the 60mA
obtained with the fixed USB low-to-high power charging
current ratio of 1:5.
Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and
X7R dielectric material types are recommended. The BAT
pin capacitor range is 1ꢁF to 22ꢁF. The VIN pin capacitor
is typically between 0.1ꢁF and 2.2ꢁF, although larger
values will not degrade performance. Capacitance must
be evaluated at the expected bias voltage, rather than the
zero-volt capacitance rating.
An arbitrary ratio of USB low-to-high power charging cur-
rents can be obtained using an external n-channel FET
operated with a processor GPIO signal to engage a second
parallel IPUSB resistor, while selecting high power mode
(MODE pin driven high) for both low or high power charg-
ing. The external circuit is illustrated in Figure 5.
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.
IPUSB
5
• 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.
RIPUSB_HI
USB Hi/Lo
Power Select
RIPUSB
Figure 5. External programming of arbitrary USB high
power and low power charge currents.
20
© 2008 Semtech Corporation
SC811 / SC813
Applications Information (continued)
For USB low power mode charging, the external transistor
is turned off. The transistor is turned on when high power
mode is desired. The effect of the switched parallel IPUSB
resistor is to reduce the effective programming resistance
and thus raise the fast-charge current.
Independent Programming of Termination
Current
The USB high power mode fast-charge current is limited
to 1000mA, twice the USB high power load limit, and so
this mode may also be used for general purpose adapter
charging. The IPRGM pin resistance to ground determines
the USB high power mode pre-charge current, and the
termination threshold current for all modes. If adapter
mode will not be used in the application, RIPRGM can be
selected to program only the termination threshold
current independently of the fast-charge current, which is
An open-drain GPIO can be used directly to engage the
parallel resistor RIPUSB_HI. Care must be taken to ensure that
the RDS-ON of the GPIO is considered in the selection of
R
IPUSB_HI. Also important is the part-to-part and tempera-
ture variation of the GPIO RDS-ON, and their contribution to
the USB High Power charge current tolerance. Note also
that IPUSB will be pulled up briefly to as high as 3V during
startup to check for an IPUSB static pinshort to ground. A
small amount of current could, potentially, flow from
IPUSB into the GPIO ESD structure through RIPUSB_HI during
this event. While unlikely to do any harm, this effect must
also be considered.
programmed with RIPUSB
.
Note that USB high power mode invokes Under-Voltage
Load Regulation, so if charging with an adapter in current
limit, the input voltage can be pulled down no lower than
VUVLR
.
USB-only Charging of Very Large Batteries
The 300mAh battery example can be used to illustrate
how this system works. The adapter mode and USB high
power mode fast-charge currents should both be set to
300mA max. The USB input low power fast-charge current
is 100mA max. Refer to the circuit in Figure 5 and the data
The SC811/3 can support the charging of very large capac-
ity batteries as high as 2Ah using a USB-only charging
source. The IPRGM resistance lower limit of 2.05kΩ is
intended to limit the fast-charge current while charging in
adapter mode to less than 1A. If only USB charging modes
will be used, then the IPRGM resistor can be chosen as low
as 1kΩ. This extended programming range allows setting
the USB high power mode pre-charge current as high as
400mA (still below the USB specification limit), and the
charge termination current as high as 200mA. (Both of
these currents are determined by RIPRGM.) Note that with
of Figures 1a and 1b. For IFQ_AD = 300mA max, use RIPRGM
7.50kΩ. A fixed IPUSB resistor of RIPUSB = 23.2kΩ programs
FQ_USB = 100mA max for USB low power charging. When a
=
I
parallel resistor RIPUSB_HI = 11.0kΩ resistor is switched in, the
equivalent IPUSB resistor is 7.50kΩ, for IFQ_USB = 300mA
max.
R
IPRGM < 2.05kΩ, adapter mode should not be used, as this
USB Low Power Mode Alternative
can result in potentially destructive fast-charge current.
Where a USB mode selection signal is not available, or for
a low capacity battery where system cost or board space
make USB low power mode external current program-
ming impractical, USB low power charging can be
supported indirectly. The IPUSB pin resistance can be
selected to obtain the desired USB high power charge
current. Then, with the MODE pin always configured for
USB high power mode, the UVLR feature will ensure that
the charging load on the VIN pin will never pull the USB
Vbus supply voltage below VUVLR regardless of the host or
hub supply limit. The UVLR limit voltage guarantees that
the voltage of the USB Vbus supply will not be loaded
below the low power voltage specification limit, as seen
by any other low power devices connected to the same
USB host or hub.
The USB high power and USB low power fast-charge cur-
rents and the USB low power pre-charge current are
determined by the resistance between IPUSB and GND to
comply with USB specified current limits, and so are unaf-
fected by the IPRGM resistor. Termination detection
requires that the charger be in CV regulation. If the
IPRGM-determined termination threshold current is set
higher than the USB low power mode fast-charge current,
for example, then charge termination will occur the instant
that the battery voltage rises to VCV. Thus USB low power
charging will behave as if trickle-charging until fully
charged, a perfectly safe and acceptable, although slow,
charging scenario.
21
© 2008 Semtech Corporation
SC811 / SC813
Outline Drawing — MLPD-UT8 2x2
B
E
A
D
DIMENSIONS
INCHES MILLIMETERS
MIN NOM MAX MIN NOM MAX
DIM
-
-
-
A
A1
A2
b
.020
.000
.024 0.50
.002 0.00
0.60
0.05
PIN 1
INDICATOR
(LASER MARK)
-
(.006)
(0.1524)
.007
0.25 0.30
.010 .012 0.18
D
D1
E
E1
e
.075 .079 .083 1.90 2.00 2.10
.061 .067 .071 1.55 1.70 1.80
.075
.026 .031 .035 0.65 0.80 0.90
.020 BSC
0.50 BSC
.079
.083 1.90 2.00 2.10
A
C
SEATING
PLANE
L
N
aaa
.012 .014 .016 0.30
0.40
0.35
8
0.08
0.10
aaa
C
8
.003
.004
A2
A1
bbb
D1
1
2
LxN
E/2
E1
N
bxN
bbb
C A B
e
e/2
D/2
NOTES:
1.
2.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
22
© 2008 Semtech Corporation
SC811 / SC813
Land Pattern — MLPD-UT8 2x2
H
DIMENSIONS
INCHES
R
DIM
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
C
G
H
K
P
R
X
Y
Z
Z
(C)
K
G
Y
P
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
23
© 2008 Semtech Corporation
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