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STw4102
Dual USB/wall adapter Li-ion battery charger with gas gauge
Features

Constant current constant voltage (CCCV) linear charger Common or separate USB/wall adapter inputs Fast charge current control up to 1 A for wall adapter and up to 500 mA for USB Support for currents higher than 1 A using external components Programmable charge voltage (4.1 V, 4.2 V, 4.3 V, 4.35 V) with 1% accuracy Thermal regulation Trickle charge mode at low battery voltage Wall adapter voltage up to 16 V Battery overvoltage protection at 4.7 V Gas gauge with 13-bit AD converter Battery voltage monitor with 7-12 bit AD converter I2C interface for device monitoring and control Charge status output pin Power detection output pin Programmable watchdog security timer 4.7 V LDO regulator (with external power MOSFET) The STw4102 offers dual charging capability using separate inputs for USB cable and wall adapter, or a single input that accepts both. The STw4102 also offers programmable fast charge current using an external resistor. A thermal regulation circuit limits the charge current against the die high power dissipation or high ambient temperature. An end of charge output pin indicates the charge termination when the fast charge current drops below 10% of the programmed current value. The STw4102 includes an accurate gas gauge based on a 13-bit AD converter. An external resistor is used between battery and ground to sense a charge/discharge current. With a typical 30 m resistor, current can be up to 2.5 A.
MAIN VOUT USBPWR DRIVER LDODRV LDOFB
1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13
QFN 24 (Plastic micropackage) Pin connections (top view)
PWRDETECTN TEST EOCHG BATTSENSE BATT SENSE
VIO SCL SDA RESETN STDBY C32KHZ
Applications

Cellular phones (GSM, CDMA, WCDMA), PDA, MP3 players, cordless phones Digital camera, USB appliances, bluetooth devices, portable navigation devices
Description
The STw4102 is a standalone constant current constant voltage (CCCV) linear charger specifically designed for Li-ion batteries.
March 2008
Rev 2
ISET CVREF GND CVIS ICG+ ICG-
1/34
www.st.com 34
Contents
STw4102
Contents
1 2 3 4 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 6 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical performance curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5
Application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 5.2 5.3 Charge from USB or wall adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Charge currents higher than 1 Amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Using LDO regulator to supply telephone from wall adapter . . . . . . . . . . 16
6
Battery charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Charge cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Trickle charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Charging from a wall adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Charging from a USB port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Charging using external power devices . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Charge mode summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Thermal regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7 8
Low drop-out regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Battery monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.1 8.2 Gas gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Battery voltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9 10
Factory OTP options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.1 Read and write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2/34
STw4102
Contents
10.2
Register mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11 12 13
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3/34
Block diagram
STw4102
1
Block diagram
Figure 1. Internal block diagram
DRIVER
MAIN
Main Power Device (max 1A)
VOUT
USBPWR
USB Power Device (max 500mA) SENSE Main adapter Detect
Driver
Thermal regulation
Current Sense BATT USB
Detect
Voltage Current Regulation
Voltage Sense
Sense ressitor
BATTSENSE
PWRDETECTN
CC/CV
Trickle threshold Trickle current Charge Voltage
CC/CV configuration
EOCHG
Charge current Current defined by external resistor
ISET
CVREF LDO LDODRV LDOFB
Vref
Main supply
Internal Supply
CVIS
LDO driver 4.7V
Battery Monitoring STDBY
Charge Control Registers
VIO SCL SDA RESETN
Power On Reset
C32KHZ
24 bit accumulator Control registers I2C interface Control Registers
AD converter 12 bits + sign bit
Battery voltage
ICG+ ICG-
AD converter 7-12 bits
GND
TEST
4/34
STw4102
Pin assignment
2
Pin assignment
Table 1.
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
P
Pin descriptions
Pin name MAIN VOUT USBPWR DRIVER LDODRV LDOFB ISET CVREF GND CVIS ICG+ ICGC32KHZ STDBY RESETN SDA SCL VIO SENSE BATT BATTSENSE EOCHG Type Supply O_A Supply O_A O_A I_A O_A I_A Ground I_A I_A I_A I_D I_D I_D IO_D I_D Supply I_A Supply I_A OD Function Main power input from wall adapter or USB charger Power path output Power supply from USB cable Driver for external power switch (PMOS or PNP) LDO power PMOS driver LDO feedback regulation Resistor to program the main charge current Bypass capacitor for internal voltage reference Analog and digital ground Bypass capacitor for internal supply Gas gauge sense resistor Gas gauge sense resistor External 32kHz clock input Gas gauge standby input (active low) Digital register reset (active low) I2C serial data. I2C serial clock. Supply for I/O Sense resistor input to regulate the charge current Battery power voltage Battery sense voltage End of charge output status. Pulled low when the fast charge current is above 10% of its programmed maximum value. Reserved pin for factory test. To be connected to ground. Main or USB plug-in detection. Pulled low when power is detected, open when no power is detected.
23 24
TEST PWRDETECTN
I_D OD
In this table, the following conventions are used: I: Input O: Output I/O: Bidirectional OD: Open Drain A: Analog D: Digital
5/34
Absolute maximum ratings and operating conditions
STw4102
3
Absolute maximum ratings and operating conditions
Table 2.
Symbol VMAIN VCC VUSB Vbatt VIO VDD Pd Isense Tstg Tj Rthja ESD
Absolute maximum ratings (AMR)
Parameter Maximum supply voltage on MAIN input Voltage on EOCHG, LDODRV, DRIVER pins Maximum supply voltage on USBPWR input Maximum voltage on BATT, BATTSENSE, PWRDETECTN Maximum supply voltage on VIO pin Voltage on I/O pins (SCL, SDA, RESETN, C32KHZ, STDBY) Power dissipation Maximum current from SENSE to BATT Storage temperature Maximum junction temperature Thermal resistance junction-ambient(1) model)(2) Value 20 -0.3 to VMAIN 7 7 7 -0.3 to VIO self-limited 1 -55 to 150 150 45 2 A
C C C/W
Unit V V V V V V
Electrostatic discharge (HBM human body
kV
1. Package's exposed pad is soldered to a copper pad on the PCB with multiple vias to the ground plane. 2. Human body model: 100 pF discharged through a 1.5 k resistor between two pins of the device, done for all couples of pin combinations with other pins floating.
Table 3.
Symbol Vmain VCC VUSB VIO Vbatt Vout Toper
Operating conditions
Parameter Operating supply voltage on MAIN Maximum voltage on EOCHG Operating supply voltage on USBPWR Operating supply voltage on VIO Max voltage on BATT, BATTSENSE, PWRDETECTN Max voltage on VOUT Operating free air temperature range Value 4.25 to 16 16 4.25 to 5.5 1.45 to 3.0 5.0 BATT +0.7 -30 to 85 Unit V V V V V V
C
6/34
STw4102
Electrical characteristics
4
Table 4.
Symbol
Electrical characteristics
CC/CV charger - Voper= 5V, Vbatt= 3.6V, Tamb = -30C to 85 C (unless otherwise specified)
Parameter Conditions Min Typ Max Unit
Supply (Voper from MAIN or USB) Icharger ISTBY Ibatt_sense Ibatt POR_IS+ POR_ISMain or USB input operating current USBPWR input standby current BSENSE input current BATT input current Power ON reset threshold+ Power ON reset thresholdCharge off No charge No charge CVIS internal supply CVIS internal supply 2.2 2.1 2.3 2.2 2 40 1 25 2.4 2.3 mA A A A V V
Voltage regulation Vcharge_acc Rpower Batteryovv Batteryovv_hyst Output voltage accuracy Power path resistance Static battery overvoltage detection Static battery overvoltage hysteresis Tamb= 0C to 85 C MAIN to BATT 4.55 -1 0.6 4.7 100 4.8 +1 % V mV
Current regulation Itrickle Vtrickle Vtrickle_hyst Icharge Icharge_acc Trickle charge current Trickle to fast charge threshold Trickle to fast charge threshold hysteresis Main charge current range Main charge current accuracy Internal path Icharge> 500mA REG_CHG0[7..6]: 00 01 10 11 % of current setting % of current setting 100 -15 30 60 200 400 0 10 5 125 100 Vbatt< Vtrickle Standard configuration Factory OTP option Standard configuration 30 60 2.8 60 120 2.9 100 1000 +15 100 500 100 180 3.0 mA mA V mV mA % mA mA mA mA % %
C
IUSB
USB charge current
EOCHGith EOCHGith_hys Tregulation Tsoftstart
End of charge threshold End of charge threshold hysteresis Regulated junction temperature Soft start from trickle to fast charge
s
7/34
Electrical characteristics Table 4.
Symbol Watchdog REG_WDOG[2,1]: 00 01 10 11 0.5 7.5 15 30 1 15 30 60
STw4102
CC/CV charger - Voper= 5V, Vbatt= 3.6V, Tamb = -30C to 85 C (unless otherwise specified) (continued)
Parameter Conditions Min Typ Max Unit
twatchdog
Watchdog duration
1.5 22.5 45 90
min min min min
Input/output pins Vcharger_det Vcharger_det_hys VUSB_det VUSB_det_hys Volpowerdetect VolEOCHG Idrv_sink Main charger supply voltage detection Main charger supply voltage detection hysterisis USB supply voltage detection USB supply voltage detection hysteresis POWERDETECTN output capability EOCHG output capability Driver sink current Isink= 10mA Isink= 10mA Isink= 20mA (If option enabled) 60 2.4 2.4 2.5 100 2.5 100 0.45 0.5 1.1 2.6 2.6 V mV V mV V V V mA
Table 5.
Symbol LDOV LDOpower_th
LDO - Vmain= 6V, Tamb = -30C to 85 C (unless otherwise specified)
Parameter LDO regulated output voltage LDO power turn off threshold Conditions Including line and load regulation (up to 1A), Vmain > 6V Min 4.47 6.8 Typ 4.7 7.2 0.7 Up to 20kHz 50 Max 4.93 7.5 Unit V V V dB
LDOpower_th_hys LDO power turn off threshold hysterisis LDOPSRR LDO power supply rejection ratio
8/34
STw4102 Table 6.
Symbol POR_IS2+ POR_IS2-
Electrical characteristics Battery monitor - Vbatt= 3.6V, Tamb = -30C to 85 C (unless otherwise specified)
Parameter Power ON reset threshold+ Power ON reset thresholdConditions CVIS internal supply CVIS internal supply Min 2.6 2.5 Typ 2.7 2.6 Max 2.8 2.7 Unit V V
Gas gauge A/D converter Vos_gg Vin_gg Idd_gg Ipdn_gg Iin LSBgg AccTamb_gg Input offset voltage Input voltage range Current consumption Current consumption in off mode Input current for ICG+ and ICGAD converter granularity (LSB value) Accuracy at ambient temperature 12 bits + 1 sign bit External resistor at 1% No calibration 23.5 3 CG_ENA=1 CG_ENA=0 -80 40 +80 90 1 500 V mV A A nA V %
Battery voltage A/D converter Vin_mon Idd_mon Ipdn_mon LSBmon Input voltage range Current consumption Current consumption in off mode AD converter granularity (LSB value) BATT voltage ADPOWERON=1 ADPOWERON=0 7 bits 12 bits No calibration 45.4 1.42 3 1 190 1 5 V A A mV mV %
AccTamb_mon Accuracy at ambient temperature
Digital I/O pins (SCL, SDA, STDBY, C32KHZ, RESETN) Vil Vih Vol Input pin low voltage Input pin high voltage SDA output pin low voltage Isink= 3mA 0 0.7 x VIO 0.3 x VIO VIO 0.2 x VIO V V V
9/34
Electrical characteristics Table 7.
Symbol Fscl thd,sta tlow thigh tsu,dat thd,dat tr tf tsu,sto Cb
STw4102
I2C timing - VIO= 2.8V, Tamb = -30C to 85 C (unless otherwise specified)
Parameter SCL clock frequency Hold time (repeated) START condition LOW period of the SCL clock HIGH period of the SCL clock Setup time for repeated START condition Data hold time Rise time of both SDA and SCL signals Fall time of both SDA and SCL signals Setup time for STOP condition Capacitive load for each bus line 0.6 1.3 0.6 0.6 0 20+ 0.1Cb 20+ 0.1Cb 0.6 400 0.9 300 300 Conditions Min Typ Max 400 Unit kHz s s s s us ns ns s pF
Figure 2.
I2C timing diagram
Vih tf
SDA
Vil thd,sta tr tsu,dat thigh
SCL
tlow thd,dat tsu,sta
10/34
STw4102
Electrical characteristics
Typical performance curves
Figure 3.
4.5 4.0 3.5 3.0 Vbatt (V)
Vbatt (V)
Charger voltage vs. charge current Figure 4. (Main charge, 4.2V and 1A settings)
4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0
Charger voltage vs. charge current (USB charge, 4.2V setting)
Ich=200mA
Ich=400mA
2.5 2.0 1.5 1.0 0.5 0.0 0 200 400 600 Icharge (mA) 800 1000 1200
0
100
200
300
400
500
Iusb (mA)
Figure 5.
Charge current vs. temperature (charge from MAIN, 1A setting)
Figure 6.
Charge current vs. temperature (charge from USBPWR)
1.2
500
1.0
Ich=400mA
400
0.8 Icharge (A) 0.6 0.4 0.2 0.0 -50
Iusb (mA) 300
Ich=200mA
200
100
-25
0
25
50
75
100
125
0 -50
-25
0
Temp (C)
25 50 Temp (C)
75
100
125
Figure 7.
4.24 4.23 4.22 Vcharge (V) 4.21 4.20 4.19 4.18 4.17 4.16 -50
Charge voltage vs. temperature (4.2V nominal setting)
-25
0
25
50
75
100
125
Temp (C)
11/34
Electrical characteristics
STw4102
Figure 8.
USB standby input current vs. temperature (charge disabled)
Figure 9.
Battery standby current vs temperature (no MAIN, no USBPWR, gas gauge disabled)
60 50 40 Iusb (A) 30 20 10 0 -50
Ibat (A)
60 50 40 30 20 10 0 -50
-25
0
25
50
75
100
125
-25
0
25
50
75
100
125
Temp (C)
Temp (C)
Figure 10. Watchdog period vs. temperature (normalized to value at 25C)
1.4
Figure 11. LDO output voltage vs. temperature (10 mA output current)
4.9
1.2 Twatchdog
4.8 LDOv (V)
1.0
4.7
0.8
4.6
0.6 -50
-25
0
25
50
75
100
125
4.5 -50
-25
0
25
50
75
100
125
Temp (C)
Temp (C)
Figure 12. LDO output voltage vs. output current
5.0 4.9 4.8 LDOv (V) 4.7 4.6
Vmain=6V Vmain=5V
4.5 4.4 0 500 LDOi (mA) 1000 1500
12/34
STw4102
Electrical characteristics
Figure 13. Waveforms at USB plug-in
Vusb
Vbatt
Ibatt 50s/div
Figure 14. Switching from USB charge to main Figure 15. Switching from main charge to USB charge charge
Vmain
Vmain
Vbatt Ibatt
Vbatt
Ibatt
100s/div
10ms/div
13/34
Application schematics
STw4102
5
5.1
Application schematics
Charge from USB or wall adapter
The MAIN input is used with either a wall adapter or a USB charger. The charge current can be programmed to 100 mA or 500 mA max for use with a USB 2.0 port, or programmed to the value set by the Rset resistor for use with a wall adapter or a dedicated USB charger. The USBPWR input is used only for charging from a USB port (100 mA or 500 mA max). Figure 16. Charge using internal power devices
from wall adapter
or USB port/charger
MAIN
C4
DRIVER
VOUT
from USB port only
C5 battery voltage
USBPWR
STw4102
SENSE BATT
to power management Indicator LED
C3
PWRDETECTN
BATTSENSE ISET
Rset
EOCHG CVIS CVREF
C2 C1
LDODRV LDOFB
IO voltage
C32KHZ STDBY
32kHz StandBy
VIO SCL SDA RESETN
ICG+
Rcg
ICGGND TEST
Reset
Table 8.
Name Rset Rcg C1 C2 C3 C4 C5
External component list
Typ. value 12k to 120k 30m 1F 1F 0.1 to 22F 0.1 to 1F 0.1 to 1F Tolerance 1% 1% Comments Main charge current setting Gas gauge sense resistor Internal supply decoupling capacitor Internal voltage reference decoupling capacitor When the battery is removed, a capacitor of at least 15F is required for low ripple on the battery line. MAIN input decoupling capacitor USBPWR input decoupling capacitor
14/34
STw4102
Application schematics
5.2
Charge currents higher than 1 Amp
One-time programming (OTP) options offer the ability to use an external power device or an external sense resistor to handle charge currents higher than 1 A from the wall adapter. These OTP options are set by STMicroelectronics at factory level. Figure 17. Charge using external power devices
D1
M1
T1
MAIN USBPWR
DRIVER
VOUT
Rs
STw4102
battery voltage
SENSE
C3
BATT
to power management
Indicator LED
PWRDETECTN
BATTSENSE ISET
Rset
EOCHG CVIS CVREF
C2 C1
LDODRV LDOFB
IO voltage
C32KHZ STDBY
32kHz StandBy
VIO SCL SDA RESETN
ICG+
Rcg
ICGGND TEST
Reset
Table 9.
Name Rset Rs T1 or M1 + D1
Component list for external power devices
Typ. value 8k to 12k 200m STT818B STS2DPFS20V Tolerance 1% 1% Comments Main charge current setting External current sense resistor PNP transistor PMOS transistor with Schottky diode
15/34
Application schematics
STw4102
5.3
Using LDO regulator to supply telephone from wall adapter
The regulator with external power PMOS (M1) supplies the telephone while the battery is discharged or unplugged. When the charger is unplugged, the phone is supplied by the battery through Power MOS M2. A Schottky diode (D1) avoids reverse current. Figure 18. Charge power path and regulator
MAIN
C4
DRIVER
VOUT
USBPWR
Battery voltage
STw4102
SENSE BATT
C3
to power management
Indicator LED
PWRDETECTN
BATTSENSE ISET
Rset
EOCHG CVIS
C2
CVREF LDODRV LDOFB C32KHZ STDBY VIO SCL SDA RESETN ICG+
C1
32kHz StandBy
IO voltage
Rcg
ICGGND TEST
Reset
M1
D1
M2
Co >= 15uF To phone
Table 10.
Name M1 + D1 M2 Co C4
Component list for LDO regulator
Typ. value STS2DPFS20V STT5PF20V 10F to 22F Co Tolerance Comments PMOS transistor with Schottky diode PMOS transistor An output capacitor Co of at least 10F is required. An input capacitor C4 equal to or larger than Co is required on MAIN input.
16/34
STw4102
Battery charger
6
6.1
Battery charger
Charge cycle
The charge cycle is initiated when the presence of a power source on either the MAIN or USBPWR inputs is detected (the PWRDETECTN pin goes low), while the charger is enabled by the CHG_ENA bit of the REG_CHG1 control register. If both supplies are connected, the MAIN input path is selected. The EOCHG output pin is driven low as the charge begins. If the battery voltage is lower than the trickle threshold, the charge cycle begins in trickle mode with a low current (default value: 60 mA) until the battery voltage reaches the trickle voltage threshold (default value: 2.9 V). Once the battery voltage rises above this threshold, the charger enters into fast charge mode where the programmed charge current Icharge or IUSB is supplied to the battery. When the battery voltage approaches the programmable charge voltage (4.10V, 4.20V, 4.30V or 4.35V), the charger enters into a constant voltage charging mode and the charging current decreases. When the current level reaches the end-of charge level (10% of Icharge), the EOCHG status pin is switched off (open) to indicate that the battery is almost fully charged, and the charger enters maintenance mode. In maintenance mode, the charger continues to monitor the battery voltage to maintain the battery voltage level. The maintenance mode lasts until the charge is stopped by clearing the CHG_ENA bit in the REG_CHG1 control register, or by removing the power source (PWRDETECTN is opened).
Figure 19. Charge flow (simplified)
Charge Off EOCH OPEN (LED OFF) Power detected (PWRDETECTN LOW) Trickle charge 60mA EOCH LOW (LED ON) Vbatt < 2.8v Vbatt > 2.9v
Power removed (PWRDETECTN OPEN) Charge Stopped EOCH OPEN (LED OFF)
CCCV charge EOCH LOW (LED ON) Icharge > 15% Icharge < 10%
Battery overvoltage or Watchdog event
Maintenance charge EOCH OPEN (LED OFF) CCCV is still ON
Battery overvoltage or Watchdog event
17/34
Battery charger
STw4102
6.2
Trickle charge
The trickle charge mode is enabled when the battery voltage Vbatt is lower than the trickle voltage threshold Vtrickle. An internal current source charges the battery. When Vbatt is above Vtrickle, the trickle current generator is off and the battery is charged using the constant current method. The trickle voltage threshold and trickle current are defined by OTP configuration bits and are factory set to 2.9 V and 60 mA by default. Other values are possible, see Section 9: Factory OTP options on page 24.
6.3
Charging from a wall adapter
The MAIN input is used for charging from a wall adapter or a dedicated USB charger. The SEL_DC_USB bit (bit 5 of register REG_CHG0) must be set to 0. The fast charge current is defined by the external resistor Rset connected to the ISET pin, and can be set up to 1 A. The value of the fast charge current is given by the following formula: Icharge = 12000 / Rset In the constant voltage mode, the charger output voltage is regulated with 1% accuracy. The charger output voltage is programmable using the REG_CHG0 register, bits 3 and 4 (see Table 11). Table 11. Charger output voltage
REG_CHG0[3] 0 1 0 1 Vcharge 4.10V +/-1% 4.20V +/-1% 4.30V +/-1% 4.35V +/-1%
REG_CHG0[4] 0 0 1 1
Figure 20. Main charge mode
Ibatt
Battery Voltage Vcharge Charge current Icharge (defined by Rset)
Vbatt
Flag end of charge (10% Icharge)
Vtrickle (2.9v)
Itrickle (60mA) Trickle charge Fast charge Constant current Maintenance charge Constant voltage
18/34
STw4102
Battery charger
6.4
Charging from a USB port
The MAIN or USBPWR input can be used to charge from a USB 2.0 port. When using the MAIN input, bit SEL_DC_USB (bit 5 of register REG_CHG0) must be set to 1. Charging from a USB port is similar to charging from a wall adapter, except the fast charge current IUSB is set internally and depends on bits 6 and 7 of the control register REG_CHG0. Table 12. USB charge current
REG_CHG0[6] 0 1 0 1 IUSB (typ) 60mA (100 mA max) 200mA 400mA (500 mA max) off
REG_CHG0[7] 0 0 1 1
6.5
Charging using external power devices
To support charge currents higher than 1 A from the main supply adapter, the STw4102 provides the option to use an external power device and sense resistor. This OTP option is factory set. The STw4102 driver is able to drive an external PNP (STT818B or equivalent) or a PMOS plus Schottky diode (STS2DPFS20V or equivalent). The driver maximum sink current is 60 mA. The external current sensing device is usually a 200 m shunt resistor. With this resistor value, the trickle and USB charge currents are close to the nominal values.
6.6
Charge mode summary
Table 13 summarizes the different charge modes. Table 13. Vbatt
0 under 1 0 0 x 1 1 1 1 above x 1 0 1 1 1 x Fast charge from MAIN input, current set by USB_ICHG bits Fast charge from USBPWR input, current set by USB_ICHG bits 0 x Trickle charge from USBPWR Fast charge from MAIN input, current set by Rset 1 x No charge Trickle charge from MAIN
Charge modes
MAIN detected x USBPWR CHG_ENA SEL_DC_USB detected bit bit x 0 x Charge Charge disabled
Vtrickle
Vtrickle
19/34
Battery charger
STw4102
6.7
Watchdog timer
When the fast charge is active, a watchdog timer starts to prevent damage on the battery. The system controller refreshes the watchdog periodically in order let the charge continue. When the watchdog time elapses, the charge is stopped. When the charge starts in trickle mode, to allow the battery to be charged although the system controller is not running, the watchdog is disabled. However, if for any reason the charger goes from fast charge mode to trickle mode, then the watchdog is not disabled to protect against battery failure. Watchdog timing can be 1 minute, 15 minutes, 30 minutes or 60 minutes. It is programmable through the I2C interface. The watchdog can be reset by the I2C interface (bit WDOG_RST) or by unplugging the charger (PWRDETECTN goes to low). The watchdog can also be enabled and disabled through the I2C interface. In the standard configuration, the default state at powerup is watchdog enabled and the timing is one minute.
6.8
Thermal regulation
A thermal regulation circuit limits the charge current in case of high power dissipation due to high input voltage or high ambient temperature. The charge current is progressively reduced to maintain the die temperature in a safe area. This allows to charge the battery with the highest possible current depending on the operating conditions, and protects the device against any damage.
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STw4102
Low drop-out regulator
7
Low drop-out regulator
The purpose of the low drop-out regulator (LDO) is to supply the phone directly from the wall adapter when the battery is low or not present. When the wall adapter is present, MOSFET is off and the phone supply is regulated at 4.7 V minus the drop voltage across D1. When the MAIN pin is not connected, MOSFET M2 is on (the gate is pulled down) and the D1 diode avoids any reverse current. The LDO output current is limited by The M1 MOSFET and D1 diode current capabilities. An output capacitor Co of at least 15 F is required. The schematics are illustrated in Figure 21. When the battery is fully discharged, the regulator can charge the battery from the main supply and at the same time supply the phone, which avoids waiting for the battery to be charged up to the minimum operating voltage before using the phone. Figure 21. Regulator
Wall adapter power supply
M1
LDODRV LDOFB
Main supply
LDO 4.7V
D1
M2
Battery power supply
Co >= 15uF
To phone
When the main supply is above the low dropout threshold LDOpower_th (about 7.2 V), then the LDO is turned off to protect the external PMOS against high power dissipation as shown in Figure 22. LDOpower_th hysteresis is around 0.7 V. By default, this protection feature is enabled, but can be disabled at factory level by OTP. Figure 22. Supply voltage
Main supply voltage 7.2V 6.5V 4.7V
Main detect ON
ON
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Battery monitoring
STw4102
8
8.1
Battery monitoring
Gas gauge
The gas gauge is designed to monitor the battery capacity. A current sensing resistor (typically of 30 m) is needed between the negative terminal of the battery and the ground. The sensing resistor voltage drop is input to a 13-bit integrating AD converter. When a conversion cycle is completed, depending on the output sign, the result is forwarded to the charge or discharge 24-bit accumulator, and the number of conversions is incremented in a 12-bit counter. One accumulator accumulates current flowing into the battery during charging and the other accumulates discharge current during system operation. The remaining battery charge is given by the difference between the charge and discharge accumulators. Figure 23. Gas gauge block diagram
Conv_number registers
13
12 bits Counter
Conv_data registers Charge registers Discharge registers
24
24
24 bit max
Charge accumulator
From 2's sign
Discharge accumulator
ICG+ ICG-
AD converter 12 bits + sign bit
EOC
to binary
cg_clock cg_enable cg_calibration
Control logic
32kHz
Control registers
The Digital Base Band (DBB) can control, enable and read gas gauge data through I2C control registers. The DBB can read the value of the most recent conversion in two's complement format by reading the CONVDATA registers. The RD_REQ bit enables the transfer of the charge/discharge accumulators and conversion counter register. The transfer can take up to eight 32 kHz cycles, therefore a delay of
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STw4102
Battery monitoring approximately 250 microseconds must be respected between the time the RD_REQ bit is set and the actual register reading. The RD_REQ bit is automatically cleared after the transfer. A high value written to the RST_CHRG, RST_DCHRG or RST_COUNTER bits of the control register resets respectively the charge accumulator, discharge accumulator or conversion counter. If these bits are set together with the RD_REQ bit, then the reset occurs after the transfer to the charge, discharge or conversion counter register respectively. The RST_CHRG, RST_DCHRG or RST_COUNTER bits are automatically cleared after the reset. The differential inputs are scaled to the full range of the AD converter, introducing a small offset error. A high value written to the CG_CAL bit of the control register connects the inputs of the AD converter together, allowing the DBB to measure the digital offset error. Using this measurement, the gas gauge can be calibrated to reduce the offset error. The conversion cycle of a 12-bit plus 1 sign-bit AD converter is 213 (8192) clock cycles. Using the 32.768kHz RTC clock, the conversion cycle time is 250 ms. The LSB value is 23.54 V, which corresponds to a current of 784.7 A with a typical 30 m sense resistor. Given a 250 ms conversion cycle time, this LSB value corresponds to a charge of 54.5 nAh. Under these conditions, the 24-bit accumulator has a capacity of 914 mAh. The gas gauge system is disabled when the battery voltage is below the Power On Reset threshold (2.7 V), or when the RESETN pin is driven low (CG_ENA bit default value is 0). During normal operation, either the STDBY pin or the CG_ENA bit can be used to disable the gas gauge function. When the STDBY pin is low, the gas gauge is disabled without waiting for the end of the current conversion. When the CG_ENA bit is low, the current gauge is disabled at the end of the current conversion.
8.2
Battery voltage monitoring
The battery voltage can be measured by means of a 7- or 12-bit A/D converter. This function is enabled and configured using the following bits of the ADCTRL register:

The ADPOWERON bit enables battery voltage monitoring. The ADRESOLUTION bit allows to select 7- or 12-bit conversion. The ONSTATE bit is set when the ADC converter is ready. The ADSTART bit starts a conversion; it is automatically cleared after writing. The ADRUN bit indicates that a conversion is in progress. The result is available when the ADRUN bit goes low, and it can be read in the ADDATA registers.
A high value written to the ADCAL bit of the control register connects the input of the A/D converter to ground, allowing the DBB to measure the digital offset error. Using this measurement, the AD converter can be calibrated to reduce the offset error. The conversion cycle of a 7 (12) bit conversion is 28=256 (213=8192) clock cycles. Using the 32.768kHz RTC clock, the conversion cycle time is 7.8 (250) ms. LSB value is 45 (1.4) mV. When the battery voltage falls below the Power On Reset threshold, or when the RESETN input is driven low, the battery voltage monitoring function is disabled.
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Factory OTP options
STw4102
9
Factory OTP options
Table 14 summarizes the one-time programming (OTP) options offered by STMicroelectronics to customize the STw4102 at factory level. Table 14. Factory OTP options
Option Configuration bits Value 60 mA 120 mA 2.3 V 2.5 V 2.7 V 2.9 V Wall adapter mode USB mode Disabled Enabled 1 min 15 min 30 min 60 min Internal External Internal External Disabled Enabled 70h 71h 72h 73h 74h 75h 76h 77h
TRICKLE current (wall adapter OTP_TC=0 (default) charge only) OTP_TC=1 OTP_TV1, OTP_TV0 : 00 01 10 11 (default) OTP_SEL_DC_USB=0 (default) OTP_SEL_DC_USB=1 OTP_WD_ENA=0 OTP_WD_ENA=1 (default) OTP_WD_TIME1, OTP_WD_TIME0 : 00 (default) 01 10 11 OPT_IEPD=0 (default) OPT_IEPD=1 OPT_IERSENSE=0 (default) OPT_IERSENSE=1 OPT_LDOEXT_PRO=0 OPT_LDOEXT_PRO=1 (default) OTP_ID2, OTP_ID1, OTP_ID0 : 000 (default) 001 010 011 100 101 110 111
TRICKLE threshold voltage
MAIN input mode at powerup Watchdog state at powerup
Watchdog period at powerup
Power switch Sense resistor LDO overvoltage protection
I2C ID address
For any option request other than the standard configuration (default values), contact STMicroelectronics to get a specific order code.
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STw4102
I2C interface
10
10.1
I2C interface
Read and write operations
The I2C interface is used to control the charging and the gas gauge system. It is compatible with the I2C specification of Philips (version 2.1). It is a slave serial interface with a serial data line (SDA) and a serial clock line (SCL): SCL: input clock used to shift data SDA: input/output bi-directional data transfers A filter rejects the potential spikes on the bus data line to preserve data integrity. The bidirectional data line supports transfers up to 400 kbit/s (fast-mode). The data is shifted into and from the chip on the SDA line, MSB first. The first bit must be high (START), followed by the Device ID and Read/Write control bit (see Table 15). The AddrID0 to AddrID2 bits are factory programmable, their default ID value is 70h (AddrID0 = AddrID1 = AddrID2 = 0). Then, the STw4102 sends an acknowledge at the end of the 8-bit transmission. The next 8 bits correspond to the address register, followed by another acknowledge. Table 16 shows the address register format. The data field is sent last. It can be composed of several 8-bit data registers, each followed by an acknowledge. Table 17 shows the data register format. The STw4102 supports byte read, word read, block read, and byte write operations. The transmission protocol is summarized in Figure 24 and Figure 25.
Table 15.
b7 1
Device ID and R/W bit format
b6 1 b5 1 b4 0 b3 AddrID2 b2 AddrID1 b1 AddrID0 b0 R/W
Table 16.
b7 RegAddr7
Address register format
b6 RegAddr6
r
b5 RegAddr5
b4 RegAddr4
b3 RegAddr3
b2 RegAddr2
b1 RegAddr1
b0 RegAddr0
Table 17.
b7 DATA7
Data register format
b6 DATA6 b5 DATA5 b4 DATA4 b3 DATA3 b2 DATA2 b1 DATA1 b0 DATA0
Figure 24. Byte, word and block read operation
Master Slave A Reg address A 8bits Restart Device id 7 bits Reg data 8bits A Reg data A 8bits address n+1 Reg data 8bits address n+2
Start Device id W 7 bits
R
A
A/A
Stop
Start bit = SDAfalling when SCL=1 Stop bit = SDArising when SCL=1 Restart bit = start after a start Acknowledge = SDA force low during a SCL clock
<-- byte read --> <-- word read (2 bytes) ----------> <-- block read (up to 10 bytes) ---------------------->
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I2C interface Figure 25. Byte write operation
Start Device id W 7 bits A Reg address A 8bits Reg data 8bits A Stop
STw4102
Start bit = SDAfalling when SCL=1 Stop bit = SDArising when SCL=1 Restart bit = start after a start
10.2
Register mapping
The mapping of all registers is shown in Table 18. Individual register descriptions are shown in Table 19 to Table 35. Power-up values are set at power startup, or at reset (RESETN pin falling edge). Charge and discharge internal accumulators are not affected by RESETN. Table 18. Register mapping
Name REG_CHG0 REG_CHG1 REG_WDOG REG_CG REG_CHARGE_LOW REG_CHARGE_MID REG_CHARGE_HIGH REG_DISCHARGE_LOW REG_DISCHARGE_MID REG_DISCHARGE_HIGH REG_CONVDATA_LOW REG_CONVDATA_HIGH REG_CONVNUMBER_LOW REG_CONVNUMBER_HIGH REG_ADCTRL REG_ADDATA_LOW REG_ADDATA_HIGH Address (dec.) 0 1 2 3 4 5 6 7 8 9 16 17 18 19 20 21 22 Description Charge control and status Charge enable Watchdog control Gas gauge control Gas gauge charge data, bits 0-7 Gas gauge charge data, bits 8-15 Gas gauge charge data, bits 16-23 Gas gauge discharge data, bits 0-7 Gas gauge discharge data, bits 8-15 Gas gauge discharge data, bits 16-23 Gas gauge AD converter data, bits 0-7 Gas gauge AD converter data, bits 8-12 Number of conversions, bits 0-7 Number of conversions, bits 8-11 Battery voltage monitor control Battery voltage monitor AD converter data, bits 0-7 Battery voltage monitor AD converter data, bits 8-10
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STw4102 Table 19.
Name CHARGERUN MAINDETECT USBDETECT VCHG
I2C interface REG_CHG0. address 0 (00h)
Pos. 0 1 2 [4,3] Type R R R R/W Powerup 0 0 0 00 Description 0: Charge is below 10% of fast charge current. 1: Charge is above 10% of fast charge current. Main input voltage detection. USB input voltage detection. Charge voltage 00=4.1V, 01=4.2V, 10=4.3V, 11=4.35V. Wall adapter/USB selection for MAIN input 0: charge current set by Rset resistor 1: charge current set by USB_ICHG bits USB charge current 00=60mA, 01=200mA, 10=400mA, 11=off.
SEL_DC_USB
5
R/W
0
USB_ICHG
[7,6]
R/W
00
Table 20.
Name CHG_ENA Reserved
REG_CHG1. address 1 (01h)
Pos. 0 [3,1] 4 Type R/W R/W R/W Powerup 1 0 0 Description 0: Charger disabled. 1: Charger enabled. Reserved bits, to be set to zero. 0: no effect. 1: force EOCHG low independently of charge state. 0: Internal supply from Main or USB input when available and charge enabled. 1: Internal supply always from Battery.
FORCECHARGER UN
SEL_IS Unused
5 [7,6]
R/W R/W
0
Table 21.
Name WDOG_EN
REG_WDOG. address 2 (02h)
Pos. 0 [2,1] 3 [5,4] 6 7 Type R/W R/W R/W R/W R R/W Powerup 1 00 0 0 x Description 0: Watchdog disabled. 1: Watchdog enabled. 00=1 minute, 01=15 minutes, 10=30 minutes, 11=60 minutes. 0: No effect. 1: Reset watchdog. Bit clear after watchdog reset. Reserved bits, to be set to zero 1: Watchdog is elapsed.
WDOG_TIME WDOG_RST Reserved WDOG_INT Unused
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I2C interface Table 22.
Name
STw4102 REG_CG. address 3 (03h)
Pos. Type Powerup 0 Description 0: Gas gauge disabled. Charge/discharge accumulators are reset. 1: Gas gauge enabled. 0: No effect. 1: Resets the charge accumulator. This bit auto clears after the charge register is reset. 0: No effect. 1: Resets the discharge accumulator. This bit auto clears after the discharge register is reset. 0: No effect. 1: Resets the counter conversion. This bit auto clears after the counter register is reset. 0: No effect. 1: Transfers the 24 bit charge/discharge accumulators and the conversion counter to the charge/discharge and conversion number registers. This bit auto clears after the transfer. 0: No effect. 1: Allows to calibrate AD converter. Set high at the end of a conversion. Cleared after read.
CG_ENA
0
R/W
RST_CHRG
1
R/W
0
RST_DCHRG
2
R/W
0
RST_COUNTER
3
R/W
0
RD_REQ
4
R/W
0
CG_CAL CG_EOC Unused
5 6 7
R/W R R/W
0 0
Table 23.
Name DATA[7..0]
REG_CHARGE_LOW. address 4 (04h)
Pos. [7..0] Type R Powerup 00 Description Current charge data.
Table 24.
Name DATA[15..8]
REG_CHARGE_MID. address 5 (05h)
Pos. [7..0] Type R Powerup 00 Description Current charge data.
Table 25.
Name DATA[23..16]
REG_CHARGE_HIGH. address 6 (06h)
Pos. [7..0] Type R Powerup 00 Description Current charge data.
Table 26.
Name DATA[7..0]
REG_DISCHARGE_LOW. address 7 (07h)
Pos. [7..0] Type R Powerup 00 Description Current discharge data.
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STw4102 Table 27.
Name DATA[15..8]
I2C interface REG_DISCHARGE_MID. address 8 (08h)
Pos. [7..0] Type R Powerup 00 Description Current discharge data.
Table 28.
Name DATA[23..16]
REG_DISCHARGE_HIGH. address 9 (09h)
Pos. [7..0] Type R Powerup 00 Description Current discharge data.
Table 29.
Name DATA[7..0]
REG_CONVDATA_LOW. address 16 (10h)
Pos. [7..0] Type R Powerup 00 AD converter data. Description
Table 30.
Name DATA[12..8] Not used
REG_CONVDATA_HIGH. address 17 (11h)
Pos. [4..0] [7..5] Type R R Powerup 0 0 Description AD converter data.
Table 31.
Name DATA[7..0]
REG_CONVNUMBER_LOW. address 18 (12h)
Pos. [7..0] Type R Powerup 0 Description Number of conversions.
Table 32.
Name DATA[11..8] Reserved
REG_CONVNUMBER_HIGH. address 19 (13h)
Pos. [3..0] [7..4] Type R R Powerup 0 x Description Number of conversions. Reserved bits.
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I2C interface Table 33.
Name ADPOWERON ONSTATE
STw4102 REG_ADCTRL. address 20 (14h)
Pos. 0 1 Type R/W R Powerup 0 0 Description 0: Allows ADC shutdown. 1: Enables ADC operation. 0: ADC is not ready for operation. 1: ADC is ready for operation. 0: No effect. 1: Allows to start a conversion. Cleared upon writing. 0: An AD conversion is not running. 1: An AD conversion is running. 0: 7 bits. 1: 12 bits. 0: No effect. 1: Allows to calibrate AD converter.
ADSTART
2
R/W
0
ADRUN ADRESOLUTION ADCAL Not used
3 4 5 [7,6]
R R/W R/W R
0 0 0 0
Table 34.
Name DATA[7..0] DATA[6..0]
REG_ADDATA_LOW. address 21 (15h)
Pos. [7..0] [6..0] Type R Powerup 00 Description AD converter data in 12 bit mode. AD converter data in 7 bit mode (bit7=0).
Table 35.
Name DATA[11..8] Not used
REG_ADDATA_HIGH. address 22 (16h)
Pos. [3..0] [7..4] Type R R Powerup 0 0 Description AD converter data in 12-bit mode (0 in 7-bit mode).
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STw4102
Package information
11
Package information
In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK(R) packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics trademark. ECOPACK specifications are available at: www.st.com. Table 36. QFN24 package mechanical data
Dimensions Ref. Typ. A A1 A2 D D1 E E1 P R e N Nd Ne L b Q D2 E2 0.20 2.10 2.10 1.95 1.95 0.42 0.17 0.50 24.00 6.00 6.00 0.40 0.30 0.18 0.50 0.30 0.45 2.25 2.25 0.24 0.13 0.65 4.00 3.75 4.00 3.75 12 0.60 0.23 Millimeters Min. 0.80 0.00 Max. 1.00 0.05 0.80 Typ. Inches Min. Max.
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Package information Figure 26. QFN24 package mechanical drawing
STw4102
Figure 27. QFN24 footprint
32/34
STw4102
Ordering information
12
Ordering information
Table 37. Order code
Temperature range -30 C, +85 C Package QFN24 Packaging Tape & reel Marking W4102I
Order code(1) STw4102IQT
1. Order code for parts with standard configuration. Contact STMicroelectronics to get order codes for parts with specific configurations.
13
Revision history
Table 38.
Date 17-Mar-2008 20-Mar-2008
Document revision history
Revision 1 2 Changes Initial release (preliminary data). Document status promoted from preliminary data to datasheet.
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STw4102
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