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| march 2008 rev 2 1/34 34 STW4102 dual usb/wall adapter li-ion battery charger with gas gauge features constant current cons tant 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 i 2 c 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) 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. 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. qfn 24 (plastic micropackage) 1 2 3 4 5 6 18 17 16 15 14 13 24 23 22 21 20 19 789101112 main vout usbpwr driver ldodrv ldofb vio scl sda resetn stdby c32khz iset cvref gnd cvis icg+ icg- pwrdetectn test eochg battsense batt sense pin connections (top view) www.st.com
contents STW4102 2/34 contents 1 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 absolute maximum ratings and operating conditions . . . . . . . . . . . . . 6 4 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 typical performance curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5 application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.1 charge from usb or wall adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.2 charge currents higher than 1 amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.3 using ldo regulator to supply telephone from wall adapter . . . . . . . . . . 16 6 battery charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6.1 charge cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6.2 trickle charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.3 charging from a wall adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.4 charging from a usb port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 6.5 charging using external power devices . . . . . . . . . . . . . . . . . . . . . . . . . . 19 6.6 charge mode summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 6.7 watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6.8 thermal regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7 low drop-out regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8 battery monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 8.1 gas gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 8.2 battery voltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 9 factory otp options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10 i 2 c interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 10.1 read and write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 STW4102 contents 3/34 10.2 register mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 11 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 12 ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 13 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 block diagram STW4102 4/34 1 block diagram figure 1. internal block diagram driver current sense voltage current regulation main usb detect cc/cv main power device (max 1a) usb power device (max 500ma) voltage sense thermal regulation sense ressitor eochg adapter detect charge voltage charge current cc/cv configuration trickle current trickle threshold ldo driver 4.7v main supply ad converter 12 bits + sign bit 24 bit accumulator control registers current defined by external resistor power on i 2 c interface reset vref internal supply vout sense batt battsense iset cvis stdby c32khz icg+ icg- gnd resetn sda scl vio ldofb ldodrv cvref pwrdetectn main usbpwr driver ad converter 7-12 bits control registers battery voltage charge control registers ldo battery monitoring test STW4102 pin assignment 5/34 2 pin assignment p in this table, the following conventions are used: i: input o: output i/o: bidirectional od: open drain a: analog d: digital table 1. pin descriptions pin # pin name type function 1 main supply main power input from wall adapter or usb charger 2 vout o_a power path output 3 usbpwr supply power supply from usb cable 4 driver o_a driver for external power switch (pmos or pnp) 5 ldodrv o_a ldo power pmos driver 6 ldofb i_a ldo feedback regulation 7 iset o_a resistor to program the main charge current 8 cvref i_a bypass capacitor for internal voltage reference 9 gnd ground analog and digital ground 10 cvis i_a bypass capacitor for internal supply 11 icg+ i_a gas gauge sense resistor 12 icg- i_a gas gauge sense resistor 13 c32khz i_d external 32khz clock input 14 stdby i_d gas gauge standby input (active low) 15 resetn i_d digital register reset (active low) 16 sda io_d i 2 c serial data. 17 scl i_d i 2 c serial clock. 18 vio supply supply for i/o 19 sense i_a sense resistor input to regulate the charge current 20 batt supply battery power voltage 21 battsense i_a battery sense voltage 22 eochg od end of charge outp ut status. pulled low when the fast charge current is above 10% of its programmed maximum value. 23 test i_d reserved pin for factory test. to be connected to ground. 24 pwrdetectn od main or usb plug-in detection. pulled low when power is detected, open when no power is detected. absolute maximum ratings and operating conditions STW4102 6/34 3 absolute maximum ratings and operating conditions table 2. absolute maximum ratings (amr) symbol parameter value unit v main maximum supply voltage on main input 20 v v cc voltage on eochg, ldodrv, driver pins -0.3 to v main v v usb maximum supply voltage on usbpwr input 7 v v batt maximum voltage on batt, battsense, pwrdetectn 7 v v io maximum supply voltage on v io pin 7 v v dd voltage on i/o pins (scl, sda, resetn, c32khz, stdby) -0.3 to v io v p d power dissipation self-limited i sense maximum current from sense to batt 1 a t stg storage temperature -55 to 150 c t j maximum junction temperature 150 c r thja thermal resistance junction-ambient (1) 1. package's exposed pad is soldered to a copper pad on the pcb with multiple vias to the ground plane. 45 c/w esd electrostatic discharge (hbm human body model) (2) 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 combinati ons with other pins floating. 2kv table 3. operating conditions symbol parameter value unit v main operating supply voltage on main 4.25 to 16 v v cc maximum voltage on eochg 16 v v usb operating supply voltage on usbpwr 4.25 to 5.5 v v io operating supply voltage on vio 1.45 to 3.0 v v batt max voltage on batt, battsense, pwrdetectn 5.0 v v out max voltage on vout batt +0.7 v t oper operating free air tem perature range -30 to 85 c STW4102 electrical characteristics 7/34 4 electrical characteristics table 4. cc/cv charger - v oper =5v, v batt =3.6v, t amb = -30c to 85 c (unless otherwise specified) symbol parameter conditions min typ max unit supply (v oper from main or usb) i charger main or usb input operating current 2 ma i stby usbpwr input standby current charge off 40 a i batt_sense bsense input current no charge 1 a i batt batt input current no charge 25 a por_is+ power on reset threshold+ cvis internal supply 2.2 2.3 2.4 v por_is- power on reset threshold- cvis internal supply 2.1 2.2 2.3 v voltage regulation v charge_acc output voltage accuracy t amb = 0c to 85 c-1 +1% r power power path resistance main to batt 0.6 battery ovv static battery overvoltage detection 4.55 4.7 4.8 v battery ovv_hyst static battery overvoltage hysteresis 100 mv current regulation i trickle trickle charge current v batt electrical characteristics STW4102 8/34 watchdog t watchdog watchdog duration reg_wdog[2,1]: 00 01 10 11 0.5 7.5 15 30 1 15 30 60 1.5 22.5 45 90 min min min min input/output pins v charger_det main charger supply voltage detection 2.4 2.5 2.6 v v charger_det_hys main charger supply voltage detection hysterisis 100 mv v usb_det usb supply voltage detection 2.4 2.5 2.6 v v usb_det_hys usb supply voltage detection hysteresis 100 mv vol powerdetect powerdetectn output capability i sink = 10ma 0.45 v vol eochg eochg output capability i sink = 10ma i sink = 20ma 0.5 1.1 v v i drv_sink driver sink current (if option enabled) 60 ma table 4. cc/cv charger - v oper =5v, v batt =3.6v, t amb = -30c to 85 c (unless otherwise specified) (continued) symbol parameter conditions min typ max unit table 5. ldo - v main =6v, t amb = -30c to 85 c (unless otherwise specified) symbol parameter conditions min typ max unit ldo v ldo regulated output voltage including line and load regulation (up to 1a), v main >6v 4.47 4.7 4.93 v ldo power_th ldo power turn off threshold 6.8 7.2 7.5 v ldo power_th_hys ldo power turn off threshold hysterisis 0.7 v ldo psrr ldo power supply rejection ratio up to 20khz 50 db STW4102 electrical characteristics 9/34 table 6. battery monitor - v batt =3.6v, t amb = -30c to 85 c (unless otherwise specified) symbol parameter conditions min typ max unit por_is2+ power on reset threshold+ cvis internal supply 2.6 2.7 2.8 v por_is2- power on reset threshold- cvis internal supply 2.5 2.6 2.7 v gas gauge a/d converter v os_gg input offset voltage 40 v v in_gg input voltage range -80 +80 mv i dd_gg current consumption cg_ena=1 90 a i pdn_gg current consumption in off mode cg_ena=0 1 a i in input current for icg+ and icg- 500 na lsb gg ad converter granularity (lsb value) 12 bits + 1 sign bit 23.5 v acc tamb_gg accuracy at ambient temperature external resistor at 1% no calibration 3% battery voltage a/d converter v in_mon input voltage range batt voltage 1 5 v i dd_mon current consumption adpoweron=1 190 a i pdn_mon current consumption in off mode adpoweron=0 1 a lsb mon ad converter granularity (lsb value) 7 bits 12 bits 45.4 1.42 mv mv acc ta m b _ m o n accuracy at ambient temperature no calibration 3 % digital i/o pins (scl, sda, stdby, c32khz, resetn) v il input pin low voltage 0 0.3 x v io v v ih input pin high voltage 0.7 x v io v io v v ol sda output pin low voltage i sink = 3ma 0.2 x v io v electrical characteristics STW4102 10/34 figure 2. i 2 c timing diagram table 7. i 2 c timing - v io = 2.8v, t amb = -30c to 85 c (unless otherwise specified) symbol parameter conditions min typ max unit f scl scl clock frequency 400 khz t hd,sta hold time (repeated) start condition 0.6 s t low low period of the scl clock 1.3 s t high high period of the scl clock 0.6 s t su,dat setup time for repeated start condition 0.6 s t hd,dat data hold time 0 0.9 us t r rise time of both sda and scl signals 20+ 0.1c b 300 ns t f fall time of both sda and scl signals 20+ 0.1c b 300 ns t su,sto setup time for stop condition 0.6 s c b capacitive load for each bus line 400 pf sda t f scl t low v il t hd,sta t r t hd,dat t su,dat t high t su,sta v ih STW4102 electrical characteristics 11/34 typical performance curves figure 3. charger voltage vs. charge current (main charge, 4.2v and 1a settings) figure 4. charger voltage vs. charge current (usb charge, 4.2v setting) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 200 400 600 800 1000 1200 icharge (ma) vbatt (v) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 100 200 300 400 500 iusb (ma) vbatt (v) ich=400ma ich=200ma figure 5. charge current vs. temperature (charge from main, 1a setting) figure 6. charge current vs. temperature (charge from usbpwr) figure 7. charge voltage vs. temperature (4.2v nominal setting) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -50-250 255075100125 temp (c) icharge (a) 0 100 200 300 400 500 -50 -25 0 25 50 75 100 125 temp (c) iusb (ma) ich=400ma ich=200ma 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 -50 -25 0 25 50 75 100 125 temp (c) vcharge (v) electrical characteristics STW4102 12/34 figure 8. usb standby input current vs. temperature (charge disabled) figure 9. battery standby current vs temperature (no main, no usbpwr, gas gauge disabled) 0 10 20 30 40 50 60 -50 -25 0 25 50 75 100 125 temp (c) iusb (a) 0 10 20 30 40 50 60 -50 -25 0 25 50 75 100 125 temp (c) ibat (a) figure 10. watchdog period vs. temperature (normalized to value at 25c) figure 11. ldo output voltage vs. temperature (10 ma output current) figure 12. ldo output voltage vs. output current 0.6 0.8 1.0 1.2 1.4 -50-250 255075100125 temp (c) twatchdog 4.5 4.6 4.7 4.8 4.9 -50 -25 0 25 50 75 100 125 temp (c) ldov (v) 4.4 4.5 4.6 4.7 4.8 4.9 5.0 0 500 1000 1500 ldoi (ma) ldov (v) vmain=6v vmain=5v STW4102 electrical characteristics 13/34 figure 13. waveforms at usb plug-in vusb vbatt ibatt 50s/div figure 14. switching from usb charge to main charge figure 15. switching from main charge to usb charge vmain vbatt ibatt 100s/div vmain vbatt ibatt 10ms/div application schematics STW4102 14/34 5 application schematics 5.1 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 r set 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 table 8. external component list name typ. value tolerance comments r set 12k to 120k 1% main charge current setting r cg 30m 1% gas gauge sense resistor c1 1f internal supply decoupling capacitor c2 1f internal voltage reference decoupling capacitor c3 0.1 to 22f when the battery is removed, a capacitor of at least 15f is required for low ripple on the battery line. c4 0.1 to 1f main input decoupling capacitor c5 0.1 to 1f usbpwr input decoupling capacitor indicator led to power battery voltage io voltage 32khz rset c1 rcg STW4102 reset standby c2 vout sense batt battsense iset cvis c32khz stdby icg+ icg- gnd resetn sda scl vio ldofb ldodrv cvref eochg pwrdetectn main usbpwr driver c3 management from wall adapter or usb port/charger from usb port only c5 c4 test STW4102 application schematics 15/34 5.2 charge currents higher than 1 amp one-time programming (otp) options offer the ab ility 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 table 9. component list for external power devices name typ. value tolerance comments r set 8k to 12k 1% main charge current setting r s 200m 1% external current sense resistor t1 or m1 + d1 stt818b sts2dpfs20v pnp transistor pmos transistor with schottky diode indicator led battery voltage 32khz rset rcg c1 standby c2 reset rs STW4102 vout sense batt battsense iset cvis c32khz stdby icg+ icg- gnd resetn sda scl vio ldofb ldodrv cvref eochg pwrdetectn main usbpwr driver io voltage c3 t1 d1 m1 to power management test application schematics STW4102 16/34 5.3 using ldo regulator to supp ly 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 table 10. component list for ldo regulator name typ. value tolerance comments m1 + d1 sts2dpfs20v pmos transistor with schottky diode m2 stt5pf20v pmos transistor co 10f to 22f an output capacitor co of at least 10f is required. c4 co an input capacitor c4 equal to or larger than co is required on main input. to phone m2 m1 d1 indicator led battery voltage 32khz rset rcg c1 standby c2 reset io voltage STW4102 vout sense batt battsense iset cvis c32khz stdby icg+ icg- gnd resetn sda scl vio ldofb ldodrv cvref eochg pwrdetectn main usbpwr driver c3 co >= 15uf to power management c4 test STW4102 battery charger 17/34 6 battery charger 6.1 charge cycle the charge cycle is initiated when the presence of a power source on either the main or usbpwr inputs is detected (t he 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 i charge or i usb 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 i charge ), 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) trickle charge 60ma cccv charge v batt > 2.9v i charge < 10% maintenance charge eoch open (led off) cccv is still on eoch low (led on) eoch low (led on) i charge > 15% v batt < 2.8v charge off eoch open (led off) power detected (pwrdetectn low) charge stopped eoch open (led off) power removed (pwrdetectn open) battery overvoltage or watchdog event battery overvoltage or watchdog event battery charger STW4102 18/34 6.2 trickle charge the trickle charge mode is enabled when the battery voltage v batt is lower than the trickle voltage threshold v trickle . an internal current source charges the battery. when v batt is above v trickle , 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 r set 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: i charge = 12000 / r set 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 ta bl e 1 1 ). figure 20. main charge mode table 11. charger output voltage reg_chg0[4] reg_chg0[3] v charge 0 0 4.10v +/-1% 0 1 4.20v +/-1% 1 0 4.30v +/-1% 1 1 4.35v +/-1% v charge v trickle (2.9v) tr i c k l e constant current constant voltage charge i trickle (60ma) (defined by r set ) i charge flag end of charge (10% i charge ) i batt v batt battery voltage charge current fast charge maintenance charge STW4102 battery charger 19/34 6.4 charging from a usb port the main or usbpwr input can be used to ch arge 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 i usb is set internally and depends on bits 6 and 7 of the control register reg_chg0. 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 equival ent). the driver maximum sink current is 60 ma. the external current sensing device is usually a 200 m shunt resistor. wi th this resistor value, the trickle and usb charge currents are close to the nominal values. 6.6 charge mode summary ta bl e 1 3 summarizes the different charge modes. table 12. usb charge current reg_chg0[7] reg_chg0[6] i usb (typ) 0 0 60ma (100 ma max) 0 1 200ma 1 0 400ma (500 ma max) 11 off table 13. charge modes v batt main detected usbpwr detected chg_ena bit sel_dc_usb bit charge - x x 0 x charge disabled 0 0 1 x no charge under v trickle 1x 1x trickle charge from main 0 1 trickle charge from usbpwr above v trickle 1x 10 fast charge from main input, current set by rset 11 fast charge from main input, current set by usb_ichg bits 0 1 1 x fast charge from usbpwr input, current set by usb_ichg bits battery charger STW4102 20/34 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 i 2 c interface. the watchdog can be reset by the i 2 c interface (bit wdog_rst) or by unplugging the charger (pwrdetectn goes to low). the watchdog can also be enabled and disabled through the i 2 c 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. STW4102 low drop-out regulator 21/34 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 capabilit ies. an output capacitor c o 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 when the main supply is above the low dropout threshold ldo power_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 . ldo power_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 ldodrv ldo 4.7v ldofb to phone m2 m1 d1 main supply battery power supply wall adapter power supply co >= 15uf main supply voltage 4.7v 7.2v on on 6.5v main detect battery monitoring STW4102 22/34 8 battery monitoring 8.1 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 the digital base band (dbb) can control, enable and read gas gauge data through i 2 c 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 tr ansfer can take up to eight 32 khz cycles, therefore a delay of ad converter 12 bits + sign bit icg+ icg- from 2 ? s to binary charge accumulator discharge accumulator 24 bit max charge registers discharge registers conv_data registers registers conv_number 12 bits counter eoc 13 24 24 control logic sign cg_enable cg_calibration cg_clock control registers 32khz STW4102 battery monitoring 23/34 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 2 13 (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 c ontrol 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 2 8 =256 (2 13 =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 powe r on reset threshold, or when the resetn input is driven low, the battery voltage monitoring function is disabled. factory otp options STW4102 24/34 9 factory otp options ta bl e 1 4 summarizes the one-time programming (otp) options offered by stmicroelectronics to customize the STW4102 at factory level. for any option request other than the standard configuration (default values), contact stmicroelectronics to get a specific order code. table 14. factory otp options option configuration bits value trickle current (wall adapter charge only) otp_tc=0 (default) otp_tc=1 60 ma 120 ma trickle threshold voltage otp_tv1, otp_tv0 : 00 01 10 11 (default) 2.3 v 2.5 v 2.7 v 2.9 v main input mode at powerup otp_sel_dc_usb=0 (default) otp_sel_dc_usb=1 wall adapter mode usb mode watchdog state at powerup otp_wd_ena=0 otp_wd_ena=1 (default) disabled enabled watchdog period at powerup otp_wd_time1, otp_wd_time0 : 00 (default) 01 10 11 1 min 15 min 30 min 60 min power switch opt_iepd=0 (default) opt_iepd=1 internal external sense resistor opt_iersense=0 (default) opt_iersense=1 internal external ldo overvoltage protection opt_ldoext_pro=0 opt_ldoext_pro=1 (default) disabled enabled i 2 c id address otp_id2, otp_id1, otp_id0 : 000 (default) 001 010 011 100 101 110 111 70h 71h 72h 73h 74h 75h 76h 77h STW4102 i 2 c interface 25/34 10 i 2 c interface 10.1 read and write operations the i 2 c interface is used to control the charging and the gas gauge system. it is compatible with the i 2 c specification of philips (ver sion 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 bi- directional 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 ta bl e 1 5 ). 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. ta bl e 1 6 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. ta b l e 1 7 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 . r figure 24. byte, word and block read operation table 15. device id and r/w bit format b7 b6 b5 b4 b3 b2 b1 b0 1 1 1 0 addrid2 addrid1 addrid0 r/w table 16. address register format b7 b6 b5 b4 b3 b2 b1 b0 regaddr7 regaddr6 regaddr5 regaddr4 regaddr3 regaddr2 regaddr1 regaddr0 table 17. data register format b7 b6 b5 b4 b3 b2 b1 b0 data 7 data 6 data 5 data 4 data 3 data 2 data 1 data 0 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 start device id reg address 8bits a restart device id r a reg data 8bits a reg data 8bits a reg data 8bits a/a address 7 bits 7 bits n+1 address n+2 stop a w master slave <-- byte read --> <-- word read (2 bytes) ----------> <-- block read (up to 10 bytes) ----------------------> i 2 c interface STW4102 26/34 figure 25. byte write operation 10.2 register mapping the mapping of all registers is shown in ta bl e 1 8 . individual register descriptions are shown in ta b l e 1 9 to ta b l e 3 5 . power-up values are set at powe r startup, or at reset (resetn pin falling edge). charge and discha rge internal accumulators are not affected by resetn. start bit = sdafalling when scl=1 stop bit = sdarising when scl=1 restart bit = start after a start start device id reg address 8bits a reg data 8bits a 7 bits stop a w table 18. register mapping name address (dec.) description reg_chg0 0 charge control and status reg_chg1 1 charge enable reg_wdog 2 watchdog control reg_cg 3 gas gauge control reg_charge_low 4 gas gauge charge data, bits 0-7 reg_charge_mid 5 gas gauge charge data, bits 8-15 reg_charge_high 6 gas gauge ch arge data, bits 16-23 reg_discharge_low 7 gas gauge discharge data, bits 0-7 reg_discharge_mid 8 gas gauge discharge data, bits 8-15 reg_discharge_high 9 gas gauge discharge data, bits 16-23 reg_convdata_low 16 gas gauge ad converter data, bits 0-7 reg_convdata_high 17 gas gauge ad converter data, bits 8-12 reg_convnumber_low 18 number of conversions, bits 0-7 reg_convnumber_high 19 number of conversions, bits 8-11 reg_adctrl 20 battery voltage monitor control reg_addata_low 21 battery voltage monitor ad converter data, bits 0-7 reg_addata_high 22 battery voltage monitor ad converter data, bits 8-10 STW4102 i 2 c interface 27/34 table 19. reg_chg0. address 0 (00h) name pos. type power- up description chargerun 0 r 0 0: charge is below 10% of fast charge current. 1: charge is above 10% of fast charge current. maindetect 1 r 0 main input voltage detection. usbdetect 2 r 0 usb input voltage detection. vchg [4,3] r/w 00 charge voltage 00=4.1v, 01=4.2v, 10=4.3v, 11=4.35v. sel_dc_usb 5 r/w 0 wall adapter/usb selection for main input 0: charge current set by rset resistor 1: charge current set by usb_ichg bits usb_ichg [7,6] r/w 00 usb charge current 00=60ma, 01=200ma, 10=400ma, 11=off. table 20. reg_chg1. address 1 (01h) name pos. type power- up description chg_ena 0 r/w 1 0: charger disabled. 1: charger enabled. reserved [3,1] r/w 0 reserved bits, to be set to zero. forcecharger un 4r/w0 0: no effect. 1: force eochg low independently of charge state. sel_is 5 r/w 0 0: internal supply from main or usb input when available and charge enabled. 1: internal supply always from battery. unused [7,6] r/w table 21. reg_wdog. address 2 (02h) name pos. type power- up description wdog_en 0 r/w 1 0: watchdog disabled. 1: watchdog enabled. wdog_time [2,1] r/w 00 00=1 minute, 01=15 minutes, 10=30 minutes, 11=60 minutes. wdog_rst 3 r/w 0 0: no effect. 1: reset watchdog. bit clear after watchdog reset. reserved [5,4] r/w 0 reserved bits, to be set to zero wdog_int 6 r x 1: watchdog is elapsed. unused 7 r/w i 2 c interface STW4102 28/34 table 22. reg_cg. address 3 (03h) name pos. type power- up description cg_ena 0 r/w 0 0: gas gauge disabled. charge/discharge accumulators are reset. 1: gas gauge enabled. rst_chrg 1 r/w 0 0: no effect. 1: resets the charge accu mulator. this bit auto clears after the charge register is reset. rst_dchrg 2 r/w 0 0: no effect. 1: resets the discharge accumulator. this bit auto clears after the discharge register is reset. rst_counter 3 r/w 0 0: no effect. 1: resets the counter conversion. this bit auto clears after the counter register is reset. rd_req 4 r/w 0 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. cg_cal 5 r/w 0 0: no effect. 1: allows to calibrate ad converter. cg_eoc 6 r 0 set high at the end of a conversion. cleared after read. unused 7 r/w table 23. reg_charge_lo w. address 4 (04h) name pos. type power- up description data[7..0] [7..0] r 00 current charge data. table 24. reg_charge_mid. address 5 (05h) name pos. type power- up description data[15..8] [7..0] r 00 current charge data. table 25. reg_charge_high. address 6 (06h) name pos. type power- up description data[23..16] [7..0] r 00 current charge data. table 26. reg_discharge_low. address 7 (07h) name pos. type power- up description data[7..0] [7..0] r 00 current discharge data. STW4102 i 2 c interface 29/34 table 27. reg_discharge_mid. address 8 (08h) name pos. type power- up description data[15..8] [7..0] r 00 current discharge data. table 28. reg_discharge_high. address 9 (09h) name pos. type power- up description data[23..16] [7..0] r 00 current discharge data. table 29. reg_convdata_low. address 16 (10h) name pos. type power- up description data[7..0] [7..0] r 00 ad converter data. table 30. reg_convdata_high. address 17 (11h) name pos. type power- up description data[12..8] [4..0] r 0 a d converter data. not used [7..5] r 0 table 31. reg_convnumber_low. address 18 (12h) name pos. type power- up description data[7..0] [7..0] r 0 number of conversions. table 32. reg_convnumber_high. address 19 (13h) name pos. type power- up description data[11..8] [3..0] r 0 number of conversions. reserved [7..4] r x reserved bits. i 2 c interface STW4102 30/34 table 33. reg_adctrl. address 20 (14h) name pos. type power- up description adpoweron 0 r/w 0 0: allows adc shutdown. 1: enables adc operation. onstate 1 r 0 0: adc is not ready for operation. 1: adc is ready for operation. adstart 2 r/w 0 0: no effect. 1: allows to start a conversion. cleared upon writing. adrun 3 r 0 0: an ad conversion is not running. 1: an ad conversion is running. adresolution 4 r/w 0 0: 7 bits. 1: 12 bits. adcal 5 r/w 0 0: no effect. 1: allows to calibrate ad converter. not used [7,6] r 0 table 34. reg_addata_low. address 21 (15h) name pos. type power- up description data[7..0] data[6..0] [7..0] [6..0] r00 ad converter data in 12 bit mode. ad converter data in 7 bit mode (bit7=0). table 35. reg_addata_high. address 22 (16h) name pos. type power- up description data[11..8] [3..0] r 0 ad converter data in 12-bit mode (0 in 7-bit mode). not used [7..4] r 0 STW4102 package information 31/34 11 package information in order to meet environmental requirements, stmicroelectronics offers these devices in ecopack ? 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 ref. dimensions millimeters inches typ. min. max. typ. min. max. a 0.80 1.00 a1 0.00 0.05 a2 0.65 0.80 d4.00 d1 3.75 e4.00 e1 3.75 12 p 0.420.240.60 r 0.170.130.23 e0.50 n 24.00 nd 6.00 ne 6.00 l 0.400.300.50 b 0.18 0.30 q0.20 0.45 d2 2.10 1.95 2.25 e2 2.10 1.95 2.25 package information STW4102 32/34 figure 26. qfn24 package mechanical drawing figure 27. qfn24 footprint STW4102 ordering information 33/34 12 ordering information 13 revision history table 37. order code order code (1) 1. order code for parts with standard configuration. contact stmicroelectr onics to get order codes for parts with specific configurations. temperature range package packaging marking STW4102iqt -30 c, +85 c qfn24 tape & reel w4102i table 38. document revision history date revision changes 17-mar-2008 1 initial rel ease (preliminary data). 20-mar-2008 2 document stat us promoted from preliminary data to datasheet. STW4102 34/34 please read carefully: information in this document is provided solely in connection with st products. stmicroelectronics nv and its subsidiaries (?st ?) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described he rein at any time, without notice. all st products are sold pursuant to st?s terms and conditions of sale. purchasers are solely responsible for the choice, selection and use of the st products and services described herein, and st as sumes no liability whatsoever relating to the choice, selection or use of the st products and services described herein. no license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. i f any part of this document refers to any third party products or services it shall not be deemed a license grant by st for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoev er of such third party products or services or any intellectual property contained therein. unless otherwise set forth in st?s terms and conditions of sale st disclaims any express or implied warranty with respect to the use and/or sale of st products including without limitation implied warranties of merchantability, fitness for a parti cular purpose (and their equivalents under the laws of any jurisdiction), or infringement of any patent, copyright or other intellectual property right. unless expressly approved in writing by an authorized st representative, st products are not recommended, authorized or warranted for use in milita ry, air craft, space, life saving, or life sustaining applications, nor in products or systems where failure or malfunction may result in personal injury, death, or severe property or environmental damage. st products which are not specified as "automotive grade" may only be used in automotive applications at user?s own risk. resale of st products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by st for the st product or service described herein and shall not create or extend in any manner whatsoev er, any liability of st. st and the st logo are trademarks or registered trademarks of st in various countries. information in this document supersedes and replaces all information previously supplied. the st logo is a registered trademark of stmicroelectronics. all other names are the property of their respective owners. ? 2008 stmicroelectronics - all rights reserved stmicroelectronics group of companies australia - belgium - brazil - canada - china - czech republic - finland - france - germany - hong kong - india - israel - ital y - japan - malaysia - malta - morocco - singapore - spain - sweden - switzerland - united kingdom - united states of america www.st.com |
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