STBC03 Datasheet Li-Ion linear battery charger with LDO and load switches Features * * * * * * * * * * * * * * * * * Maturity status link STBC03 Device summary Order code STBC03JR LDO 3.0 V Package 400 m pitch Charges single-cell Li-Ion batteries with CC/CV algorithm and charge termination Fast charge current up to 650 mA adjustable by external resistor Pre-charge current from 1 mA Adjustable floating voltage up to 4.45 V Integrated low quiescent LDO regulator Automatic power path management Auto-recharge function Embedded protection circuit module (PCM) featuring battery overcharge, battery over-discharge and battery overcurrent protections Charging timeout Shipping mode feature allows battery low leakage when over-discharged Very low battery leakage in over-discharge and shutdown mode Charger enable input Charge/fault status output Battery voltage pin to allow external gauging Two 3 SPDT load switches Available in Flip Chip 30, 400 m pitch package Rugged 4 kV HBM, ESD protection on the most critical pins Applications * * * Smart watches and wearable devices Fitness and medical accessories Li-Ion and other Li-Poly battery rechargeable equipment Description The STBC03 is a highly integrated power management, embedding a linear battery charger, a 150 mA LDO, 2 SPDT load switches, and a protection circuit module (PCM) to prevent the battery from being damaged under fault conditions. The STBC03 uses a CC/CV algorithm to charge the battery; the fast charge and the pre-charge current can be both independently programmed using dedicated resistors. The termination current is set to 5% of the programmed fast charge current, but has fixed values for fast charge currents lower than 20 mA. The battery floating voltage value is programmable and can be set to a value up to 4.45 V. The STBC03 also features a charger enable input to stop the charging process anytime. The STBC03 is automatically powered off from the connected battery when the IN pin is not connected to a valid power source (battery mode). A battery under/overtemperature condition can be detected by using an external circuitry (NTC thermistor). DS11889 - Rev 4 - March 2018 For further information contact your local STMicroelectronics sales office. www.st.com STBC03 The STBC03 draws less than 10 nA from the connected battery in shipping mode conditions, so to maximize the battery life during shelf life of the final application. The device is available in the Flip Chip 30 package. DS11889 - Rev 4 page 2/32 STBC03 Application schematic 1 Application schematic Figure 1. STBC03 application schematic Table 1. Typical bill of material (BOM) Symbol Value Description Note CIN 10 F (16 V) Input supply voltage capacitor Ceramic type CSYS 1 F (10 V) System output capacitor Ceramic type RISET Refer to ISET Charge current programming resistor Film type RIPRE Refer to IPRE Pre-charge current programming resistor Film type CBAT 4.7 F (6.3 V) Battery positive terminal capacitor Ceramic type RFLOAT BATSNSFV Floating voltage programming resistor Film type RDIV1, DIV2 100-200 k Battery monitor resistor divider Film type RCHG 10 k Charging/fault pull-up resistor(1) Film type CLDO 1.0 F (10 V) LDO output capacitor Ceramic type 1. RCHG must be calculated according to the external LED electrical characteristics. DS11889 - Rev 4 page 3/32 STBC03 Pin configuration 2 Pin configuration Figure 2. Pin configuration top through view Table 2. Pin description Bump Power Programming Sensing Digital I/Os Bump name Description IN E5-F5 Input supply voltage. Bypass this pin to ground with a 10 F capacitor BAT A5-B5 Battery positive terminal. Bypass this pin to GND with a 4.7 F ceramic capacitor SYS C5-D5 System output. Bypass this pin to ground with 1 F ceramic capacitor LDO F4 LDO output. Bypass this pin to ground with 1 F ceramic capacitor NTC D1 Battery temperature monitor pin AGND B4 Analog ground GND A3 GROUND ISET A4 Fast charge current programming resistor IPRE D4 Pre-charge current programming resistor BATMS C4 Battery voltage measurement pin BATSNS B3 Battery voltage sensing. Connect as close as possible to the battery positive terminal BATSNSFV A2 Floating voltage sensing. Connect as close as possible to the battery positive terminal CEN B1 Charger enable pin. Active high. 500 k internal pull-up (to LDO) CHG E1 Charging/fault flag. Active low (open drain output) WAKE-UP D2 Shipping mode exit input pin. Active high. 50 k internal pull-down SW_SEL2 C1 Load switch 2 selection input (refer to LDO level) BATMS_EN C2 Battery monitor enable input (refer to LDO level) SW_SEL1 B2 Load switch 1 selection input (refer to LDO level) A1 Shutdown input signal (refer to LDO level). When low, the STBC03 exits ship mode. It cannot be left floating SD DS11889 - Rev 4 Connect together with the same ground layer page 4/32 STBC03 Pin configuration Bump Bump name F3 Load switch SPDT1 input (1.8 V to 5 V range) SW1_OA E4 Load switch SPDT1 output A SW1_OB E3 Load switch SPDT1 output B E2 Load switch SPDT2 input (1.8 V to 5 V range) SW2_OA F2 Load switch SPDT2 output A SW2_OB F1 Load switch SPDT2 output B NC C3-D3 Not connected SW1_I Switch matrix SW2_I DS11889 - Rev 4 Description If SPDT switches are used, decoupling capacitors are recommended on input and output. Capacitor values depend on application conditions and requirements. If not used, connect inputs and outputs to GND Leave floating page 5/32 STBC03 Maximum ratings 3 Maximum ratings Table 3. Absolute maximum ratings Note: Symbol Parameter Test conditions Value Unit VIN Input supply voltage pin DC voltage -0.3 to +10.0 V Non repetitive, 60 s pulse length -0.3 to +16.0 V VLDO LDO output pin voltage DC voltage -0.3 to +4.0 V VSYS SYS pin voltage DC voltage -0.3 to +6.5 V VSW Switch pin voltage (SW1_I, SW2_I, SW1_OA, SW1_OB, SW2_OA, SW2_OB) DC voltage -0.3 to +6.5 VCHG CHG pin voltage DC voltage -0.3 to +6.5 V VWake-up WAKE-UP pin voltage DC voltage -0.3 to +4.6 V VLGC Voltage on logic pins (CEN, SW_SEL1, SW_SEL2, SD,BATMS_EN) DC voltage -0.3 to +4.0 V VISET, VIPRE Voltage on ISET, IPRE pins DC voltage -0.3 to +2 V VNTC Voltage on NTC pin DC voltage -0.3 to VLDO V VBAT, VBATSNS, VBATSNSFV Voltage on BAT, BATSNS and BATSNSFV pins -0.3 to +5.5 V VBATMS Voltage on BATMS pin DC voltage -0.3 to VBAT+0.3 V ESD Human body model (IN, SYS, WAKE-UP, LDO, BAT, BATSNS, BATSNSFV) JS-001-2012 vs. AGND PGND and GND 4000 V Human body model (all the others) JS-001-2012 2000 V DC voltage V TAMB Operating ambient temperature -40 to +85 C TJ Maximum junction temperature +125 C TSTG Storage temperature -65 to +150 C Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Table 4. Thermal data Symbol RTHJB (1) Parameter Flip Chip 30 (2.25x2.59 mm) Unit Junction-to-pcb board thermal resistance 50 C/W 1. Standard FR4 pcb board. DS11889 - Rev 4 page 6/32 STBC03 Electrical characteristics 4 Electrical characteristics VIN=5 V, VBAT = 3.6 V, CLDO = 1 F, CBAT = 4.7 F, CIN = 10 F, CSYS = 1 F, RISET = 1 k, SD = GND, CEN = high, RIPRE = 4.7 k, TA = 25 C, SW_SEL1 = SW_SEL2 = GND, BATMS_EN = GND, WAKE-UP floating unless otherwise specified. Table 5. Electrical characteristics Symbol Test conditions Min. Max. Unit VFLOAT set 4.2 V, IFAST < 250 mA 4.55 5.4 V Operating input voltage VFLOAT set 4.45 V, IFAST < 450 mA, ISYS = ILDO = 0 mA 4.75 5.4 (1) V VINOVP Input overvoltage protection VIN rising 5.6 6.4 V VINOVPH Input overvoltage protection hysteresis VIN falling 200 mV VUVLO Undervoltage lock-out VIN falling 3.9 V VUVLOH Undervoltage lock-out hysteresis VIN rising 300 mV Charger disabled mode (CEN = low), ISYS = ILDO = 0A 600 A Charging, VHOT < VNTC < VCOLD, including RISET current 1.4 mA VIN IIN VFLOAT IBAT IFAST Parameter IN supply current Battery floating voltage BAT pin supply current Fast charge current IBAT = 1 mA, BATSNS and BATSNSFV short to battery terminal 4.179 Typ. 5.9 4.2 4.221 V Battery-powered mode (VIN < VUVLO), ILDO = 0 A 4 8 A Charge terminated 9 12 A Shutdown mode (by SD pin) 10 50 Over-discharge mode (VBAT < VODC, VIN < VUVLO) 10 50 RISET = 300 650(1) RISET = 430 , constant-current mode ILDO+ ISYS < 150 mA 450(1) 500 nA mA RISET = 1 k, constant-current mode 200 RIPRE = 10 k, constant-current mode 20 mA IPRE Pre-charge current VISET ISET regulated voltage 1 V VIPRE IPRE regulated voltage 1 V VPRE Pre-charge to fast charge battery voltage threshold Charger active 3 V IEND End-of-charge current Charging in CV mode for 20 mA < IFAST 5 %IFAST VOCHG Battery voltage overcharge threshold Charging in CV mode for IFAST< 20 mA VBAT rising, BATSNSFV short to battery terminal See Table 10. IFAST and IEND 4.245 VBAT rising, external resistor between BATSNSFV and battery terminal 4.275 4.305 VFLOAT+75 V mV VODC Battery voltage over-discharge threshold VIN < VUVLO, ILDO = 150 mA, BATSNSFV and BATSNS short to battery terminal VODCR Battery voltage over-discharge release threshold VUVLO < VIN < VOVP, ILDO = 150 mA, BATSNSFV and BATSNS short to battery terminal 3.0 V Wake-up voltage threshold VBAT>3 V rising, ILDO = 150 mA 2.2 V VWAKE-UP DS11889 - Rev 4 2.750 2.8 2.850 V page 7/32 STBC03 Electrical characteristics Symbol Parameter Test conditions Min. Typ. Max. Unit RON-IS Input to SYS on-resistance 0.25 0.35 RON-BS Battery to SYS on-resistance 0.35 0.4 RON-BATMS BATSNS to BATMS on-resistance ISINK = 500 A 290 550 RON-LOADSW1 Input to output load switch 1 resistance VSW1_I = 1.8 V to 5 V SW1_OA or SW1_OB test current = 50 mA 2.0 3.8 RON-LOADSW2 Input to output load switch 2 resistance VSW2_I = 1.8 V to 5 V 2.0 3.4 VOL Output low level (CHG) ISINK = 5 mA 0.4 V IOHZ High level open drain output current (CHG) VOH = 5 V 1 A VIL Logic low input level (CEN, SW_SEL1, SW_SEL2, BATMS_EN, SD) 0.4 V VIH Logic high input level (CEN, SW_SEL1, SW_SEL2, BATMS_EN, SD) 1.6 RUP CEN pull-up resistor 375 500 625 k VLDO LDO output voltage ILDO = 1 mA 2.9 3.0 3.1 V LDO static load regulation ILDO = 1 mA to 150 mA 0.002 0.003 %/mA ISC LDO short-circuit current RLOAD = 0 tON LDO turn-on time VOUT-LOAD SW2_OA or SW2_OB test current = 50 mA 350 mA 0 to 95% VLDO, IOUT = 150 mA 210 s Battery discharge overcurrent protection VIN VILIMSCTH; VUVLO < VIN < VINOVP (powered from IN) 1.7 A SYS voltage threshold for input current limitation short-circuit detection VUVLO < VIN < VINOVP 2 V SYS short-circuit protection threshold VIN < VUVLO or VIN>VINOVP (powered from BAT) VBAT-0.8 V INTCB NTC pin bias current VNTC = 0.25 V VHOT Thermal hot threshold VCOLD THYST IBATOCP IINLIM VILIMSCTH VSCSYS 250 V 45 50 55 A Increasing NTC temperature 0.234 0.246 0.258 V Thermal cold threshold Decreasing NTC temperature 1.28 1.355 1.43 V Hot/cold temperature thresholds hysteresis 10 k NTC, = 3370 3 C Thermal shutdown die temperature 155 C TWRN Thermal warning die temperature 135 C tPW-VIN Minimum input voltage connection time to exit from shutdown mode VBAT = 3.5 V, RNTC = 10 k 240 ms tOCD Overcharge detection delay VBAT> VOCHG, VUVLO VINOVP 60 ms tDOD Discharge overcurrent detection delay IBAT> IBATOCP, VIN VINOVP 10 ms tPFD Pre-charge to fast charge transition Rising deglitch time 100 ms TSD DS11889 - Rev 4 page 8/32 STBC03 Electrical characteristics Symbol Parameter Test conditions Min. Typ. Max. Unit tFPD Fast charge to pre-charge fault deglitch time 10 ms tEND End-of-charge deglitch time 100 ms tPRE Pre-charge timeout 1800 s tFAST Fast charge timeout tCRDD Charger restart deglitch time After end-of-charge, VBAT < 3.9 V restart enabled VREC Charger restart threshold After end-of-charge, restart enabled tNTCD Battery temperature transition deglitch time tPW tPW-WA CEN valid input pulse width WAKE-UP valid input pulse width VBAT = 2 V, charging 14000 18000 22000 s 1200 ms 3.9 V 100 ms 15 ms 1200 ms 1. If the internal thermal temperature of the STBC03 reaches TWRN, then the programmed IFAST is halved until the internal temperature drops below TWRN - 10 C typically. A warning is signaled via the CHG output. DS11889 - Rev 4 page 9/32 STBC03 Typical performance characteristics 5 Typical performance characteristics Figure 3. Battery mode 3 V LDO load transient response Figure 4. Thermal management VBAT = 3.7 V, 10 mA to 150 mA, slope 150 mA/1 s VBAT = 3.7 V, VIN = 5.0 V CH2 (red) = LDO 1 V/div CH1 (blue) = VIN CH3 (green) = LDO 10 mV/div CH2 (red) = LDO CH4 (pink) = LDO load variation CH3 (green) = CHG CH4 (pink) = IBAT Figure 5. VIN mode, overvoltage protection Charging is resumed when OVP disappears CH1 (blue) = VIN 800 mV/div CH2 (red) = VSYS 800 mV/div CH3 (green) = VBAT 800 mV/div CH4 (pink) = IBAT 20 mA/div DS11889 - Rev 4 Figure 6. Pre-charge to fast charge mode transition threshold CH1 (blue) = VIN 800 mV/div CH2 (red) = VSYS 800 mV/div CH3 (green) = VBAT 800 mV/div CH4 (pink) = IBAT 20 mA/div page 10/32 STBC03 Typical performance characteristics Figure 7. Pre-charge to fast charge mode transition deglitch Figure 8. Pre-charge to fast charge mode to no charge mode transition CH1 (blue) = VIN 800 mV/div CH1 (blue) = VIN 800 mV/div CH2 (red) = VSYS 800 mV/div CH2 (red) = VSYS 800 mV/div CH3 (green) = VBAT 800 mV/div CH3 (green) = VBAT 800 mV/div CH4 (pink) = IBAT 20 mA/div CH4 (pink) = IBAT 20 mA/div Figure 9. Wake-up pin operation Figure 10. VIN plug, charging initialization Shutdown mode to battery mode transition. VIN floating Shutdown mode to VIN mode transition CH1 (blue) = WAKE-UP pin 800 mV/div CH1 (blue) = VIN 800 mV/div CH2 (red) = VSYS 800 mV/div CH2 (red) = VSYS 800 mV/div CH3 (green) = VBAT 800 mV/div CH3 (green) = VBAT 800 mV/div CH4 (pink) = IBAT 20 mA/div DS11889 - Rev 4 page 11/32 STBC03 Typical performance characteristics Figure 11. Wake-up operation, VSYS and LDO rise overview Figure 12. Wake-up operation, VSYS and LDO rise detail CH1 (blue) = VLDO 800 mV/div CH1 (blue) = VLDO 800 mV/div CH2 (red) = VSYS 800 mV/div CH2 (red) = VSYS 800 mV/div CH3 (green) = VBAT 800 mV/div CH3 (green) = VBAT 800 mV/div CH4 (pink) = Wake-up 3 V/div CH4 (pink) = Wake-up 3 V/div Figure 13. VIN plug, charging initialization battery mode to VIN mode transition Figure 14. Shutdown mode entry CH1 (blue) = VIN 800 mV/div By SD pin CH2 (red) = VSYS 800 mV/div CH1 (blue) = SD pin, 1 V/div CH3 (green) = VBAT 800 mV/div CH2 (red) = SYS pin, 1 V/div CH4 (pink) = IBAT 20 mA/div DS11889 - Rev 4 page 12/32 STBC03 Typical performance characteristics Figure 15. VBAT to VSYS drop and VSYS to VLDO drop (10 mA) Figure 16. VBAT to VSYS drop and VSYS to VLDO drop (100 mA) LDO loaded by 10 mA; VODC cut-off LDO loaded by 100 mA; VODC cut-off CH1 (blue) = VLDO 400 mV/div CH1 (blue) = VLDO 400 mV/div CH2 (red) = VSYS 400 mV/div CH2 (red) = VSYS 400 mV/div CH3 (green) = VBAT 400 mV/div CH3 (green) = VBAT 400 mV/div CH4 (pink) = ILDO 10 mA/div CH4 (pink) = ILDO 20 mA/div Figure 17. CEN operation Figure 18. CEN operation, VIN plug/unplug CH1 (blue) = CEN 3 V/div CH1 (blue) = IN pin 3.0 V/div CH3 (green) = VBAT 800 mV/div CH3 (green) = CEN 2.0 V/div CH4 (pink) = IBAT 20 mA/div CH4 (pink) = IBAT 30 mA/div DS11889 - Rev 4 page 13/32 STBC03 Functional pin description 6 Functional pin description 6.1 GND, AGND The STBC03 ground pins. 6.2 NTC The battery temperature monitoring pin. Connect the battery NTC thermistor to this pin. The charging cycle stops when the battery temperature is outside of the safe temperature range (0 C to 45 C). When the charging cycle is completed, the NTC pin goes to a high impedance state, therefore the NTC thermistor can be also used, together with an external circuitry, to monitor the battery temperature while it is being discharged. If the NTC thermistor is not used, a 10 k resistor must be connected to ensure proper IC operations. 6.3 ISET, IPRE Fast and pre-charge current programming pins. Connect two resistors (RISET, RIPRE) to ground to set the fast and pre-charge current (IFAST, IPRE) according to the following equation (valid for IFAST, IPRE > 5 mA): Equation 1: VIPRE IPRE = *K ; RIPRE VISET I = *K RISET FAST (1) Where VISET = VIPRE = 1 V and K = 200. Fast charge and pre-charge currents can be independently set from 1 mA to 650 mA. End-of-charge current value is typically 5% of the fast charging current value being set. For low charging current (IFAST, IPRE < 5 mA), the RISET and RIPRE values in the following table must be used. Table 6. Charging current setting IFAST, IPRE RISET, RIPRE 5 mA 40.5 k 2 mA 110 k 1 mA 260 k Both RISET and RIPRE must be always used. Short-circuit to ground or open circuit are not allowed options. 6.4 BATMS, BATMS_EN Battery voltage measurement. If BATMS_EN is high, the BATMS pin is internally shorted to the BATSNS pin during normal conditions to monitor the battery voltage using external components (C and embedded ADC). The internal path from BATMS pin to the battery is opened in case any of the following conditions occur: overcurrent, battery over-discharge, shutdown mode, short-circuit on SYS or LDO. To minimize overall system power consumption, this function must be disabled. BATMS_EN pin should be pulled low. 6.5 BATSNS, BATSNSFV Battery voltage sense pin. The BATSNS pin must be connected as close as possible to the battery positive terminal to ensure the maximum accuracy on the floating voltage and on the battery voltage protection thresholds. The BATSNSFV pin can be used to fix the VFLOAT value by connecting a proper external series resistor to BATSNSFV. The battery floating voltage can be set up to 4.45 V according to the following equation: DS11889 - Rev 4 page 14/32 STBC03 BAT Equation 2: Rfloat Rfloat Vfloatadj = Vfloatdef * 1 + V = 4.2* 1 + V 1M 1M (2) Example: to set the battery floating voltage for 4.35 V, refer to the following equation. Equation 3: Rext = 1M * Vfloatadj 4.35V - 1 = 1M* - 1 = 35.7K 4.2V 4.2V (3) If the BATSNSFV pin is connected to the battery positive terminal, the floating voltage is set for its 4.2 V default value. 6.6 BAT External battery connection pin (positive terminal). A 4.7 F ceramic bypass capacitor must be connected to GND. 6.7 IN 5 V input supply voltage pin. The STBC03 is powered off from this pin when a valid voltage source is detected, meaning a voltage higher than VUVLO and lower than VINOVP. A 10 F ceramic bypass capacitor must be connected to GND. 6.8 SYS The internal LDO input voltage and external unregulated supply pin. The maximum current deliverable through this pin depends on the following two conditions: LDO load and battery status. However, if none of the above loads sinks current, the maximum SYS current budget is 650 mA, provided that the input voltage source can deliver that amount of current. SYS voltage source can be either IN or BAT, depending on the operating conditions (refer to the following table). A ceramic bypass capacitor of 1 F must be connected to GND. Table 7. SYS voltage source VIN VBAT SYS status LDO status < VUVLO < VODC (1) Not powered Off < VUVLO > VODC VBAT On > < VUVLO and < VINOVP X (don't care)(3) VIN On > VINOVP < VODC Not powered Off > VINOVP > VODC VBAT On 1. VODCR if the shutdown mode or the over-discharge protection has been previously activated. 2. Voltage drop over internal MOSFET is not included. 3. Battery disconnected (0 V) or fully discharged. Resistive short-circuit is not supported for safety reasons. 6.9 LDO LDO output voltage pin. The maximum current capability is anyhow 150 mA. A 1 F ceramic bypass capacitor must be connected to GND. DS11889 - Rev 4 page 15/32 STBC03 WAKE-UP 6.10 WAKE-UP Wake-up input pin. To restore normal operations of the STBC03, so to exit from a shutdown condition, connect the WAKE-UP pin to the battery voltage. The STBC03 is enabled to operate in normal conditions again, only if the battery voltage is higher than VODCR (3 V). A deglitch delay is implemented to prevent unwanted false operations. The above-described WAKE-UP pin functionality is disabled when a valid VIN voltage source is detected. The pin has an internal 50 k pull-down resistor. 6.11 CHG Active low, open drain charging/fault flag output pin. The CHG provides status information about VIN voltage level, battery charging and faults by toggling at different frequencies as reported in the table below. Table 8. CHG pin state Device state CHG pin state Not valid input (VIN < VBAT or VIN > VINOVP or VIN < VINUVLO) High Z (high by external pull-up) Valid input (VIN >VINUVLO, VIN < VINOVP, VBAT < VIN and CEN low) Low End-of-charge (EOC) 6.12 Note Toggling 4.1 Hz (until USB is disconnected) Charging phase (pre and fast) Toggling 6.2 Hz Overcharge fault Toggling 8.2 Hz Charging timeout (pre-charge, fast charge) Toggling 10.2 Hz Battery voltage below VPRE after the fast charge starts Toggling 12.8 Hz Charging thermal limitation (thermal warning) Toggling 14.2 Hz Battery temperature fault (NTC warning) Toggling 16.2 Hz In case of synchronous alarm events, the highest toggling frequency has higher priority. Example: NTC warning and EOC are concurrent events. NTC warning, signaled by toggling CHG at 16.2 Hz is the only signal available till the battery temperature goes back to a safe range (0 C to 45 C). If an EOC condition is still present then a 4.1 Hz toggling signal is present. CEN Internal CC/CV charger block enable pin. A low logic level on this pin disables the internal CC/CV charger block. Transitioning CEN from high to low and then back to high, allows the CC/CV charger block to be restarted if it was stopped due to one of the following conditions: * Charging timeout (pre-charge, fast charge) * Battery voltage below VPRE after the fast charge has already started * End-of-charge CEN has no effect if the charging cycle has been stopped by a battery overcharge condition. If the CC/CV charger stops the charging cycle due to an out of range battery temperature, a low logic level on the CEN pin disables the CC/CV charger and resets the charging timeout timers. If CEN is set high, the CC/CV charger restarts normal operations, assuming that no fault condition is detected. CEN is internally pulled up to DS11889 - Rev 4 page 16/32 STBC03 SD LDO via a 500 k resistor and must be either left floating or tied to LDO when the STBC03 is powered for the first time. Should the auto-recharge function be enabled, the CC/CV charger restarts automatically charging the battery if VBAT goes below 3.9 V; a deglitch time delay has been added to prevent unwanted charging cycle from restarting. 6.13 SD The shutdown pin. In battery mode (if no valid VBUS voltage is present) a logic high level on this pin asserts the low power consumption mode. If SD is kept high when a pulse is applied to WAKE-UP pin the device exits the shutdown condition for the duration of the WAKE-UP pulse. In shutdown mode, the battery drain is then reduced to less than 50 nA. If a valid VBUS voltage is present, the SD pin status has no effect and the device is always out of the shutdown condition. 6.14 SW1_OA, SW1_OB, SW1_I, SW2_OA, SW2_OB, SW2_I SPDT load switch pins. Both of SPDT load switches are controlled by the digital control pins (see section below). Each SPDT features a typical RDS(on) of 3 . SPDT load switches can be paralleled to reduce the series resistor as well as to increase the allowable flowing current. 6.15 SW_SEL1 and SW_SEL2 SW_SEL1 and SW_SEL2 drive the SPDT switches according to the following table. They should be connected to GND if not used. Table 9. SW_SEL1, SW_SEL2 operation INPUTS DS11889 - Rev 4 OUTPUTS SW_SEL 1 SW_SEL2 SW1_OA SW1_OB SW2_OA SW2_OB 0 0 SW1_I Hi-Z SW2_I Hi-Z 1 0 Hi-Z SW1_I SW2_I Hi-Z 0 1 SW1_I Hi-Z Hi-Z SW2_I 1 1 Hi-Z SW1_I Hi-Z SW2_I page 17/32 STBC03 Block diagram 7 Block diagram Figure 19. STBC03 block diagram DS11889 - Rev 4 page 18/32 STBC03 Operation description 8 Operation description The STBC03 is a power management IC integrating a battery charger with an embedded power path function, a 150 mA low quiescent LDO, two SPDT load switches and a protection circuit module (PCM) to prevent the battery from being damaged. When powered off from a single-cell Li-Ion or Li-Poly battery, and after having performed all the safety checks, the STBC03 starts charging the battery using a constant-current and constant-voltage algorithm. The embedded power path allows simultaneously the battery to be charged and the overall system to be supplied. By contrast, when the input voltage is above the valid range, the battery supplies the LDO as well as every load connected to SYS. The STBC03 also protects the battery in case of: * Overcharge * Over-discharge * Charge overcurrent * Discharge overcurrent If a fault condition is detected when the input voltage is valid (VUVLO < VIN < VINOVP), the CHG pin starts toggling, signaling the fault. The device can also be in shutdown mode (shutdown IBAT < 50 nA) maximizing the battery life of the end-product during its shelf life. 8.1 Power-on When the STBC03 is in shutdown mode, any load connected to LDO and to SYS is not supplied. An applied valid input voltage (VUVLO < VIN < VINOVP) for at least 250 ms, regardless the presence of a battery or if the battery is fully depleted, allows the loads connected to SYS and LDO to be supplied, thus enabling proper system operations. The CEN pin must be left floating or tied high (LDO level) during the power-on for proper operations. The STBC03 can be also turned on when VIN is outside the valid range, below the conditions that the battery has at least a remaining charge of 3 V and the wake-up input is properly triggered. The STBC03 features an UVLO circuit that prevents oscillations if the input voltage source is unstable. The CEN pin must be left floating or tied to a high level (LDO) when the STBC03 is powered. 8.2 Battery charger The STBC03 allows single-cell Li-Ion and Li-Poly battery chemistry to be charged up to a 4.45 V using a CC/CV charging algorithm. The charging cycle starts when a valid input voltage source (VUVLO < VIN < VINOVP) is detected and signaled by the CHG pin toggling from a high impedance state to a low logic level. If the battery is deeply discharged (the battery voltage is lower than VPRE), the STBC03 charger enters the precharge phase and starts charging in constant-current mode with the pre-charge current (IPRE) set. In case the battery voltage does not reach the VPRE threshold within the tPRE time, the charging process is stopped and a fault is signaled. By contrast, as soon as the battery voltage reaches the VPRE threshold, the constant-current fast charge phase starts operating, and the relevant charging current increases to the IFAST level. Likewise, if the constant current fast charge phase is not completed within tFAST, meaning that VBAT < VFLOAT, the charging process is stopped and a fault is signaled (CHG starts toggling at 10.2 Hz as long as a valid VIN is present). Should the battery voltage decrease below VPRE during the fast charge phase, the charging process is halted and a fault is signaled. The constant-current fast charge phase lasts until the battery voltage is lower than VFLOAT. After that, the charging algorithm switches to a constant-voltage (CV) mode. During the CV mode, the battery voltage is regulated to VFLOAT and the charging current starts decreasing over time. As soon as it goes below IEND, the charging process is considered to be completed (EOC, end-of-charge ) DS11889 - Rev 4 page 19/32 STBC03 Battery charger and the relevant status is signaled via a 4.1 Hz toggling signal on the CHG pin, again as long as a there is a valid input source applied (VUVLO < VIN < VINOVP). Both IPRE and the IFAST values can be programmed from 1 mA to 450 mA via an external resistor, as described in the ISET pin description. For any IFAST programmed value above 20 mA, the IEND value can be set either 5% or 2.5% of the IFAST level. For any IFAST programmed value below 20 mA, the relevant IEND value is set as per the following table: Table 10. IFAST and IEND IFAST IEND 20 mA 1.7 mA 10 mA 1.1 mA 5 mA 0.65 mA 2 mA 0.4 mA 1 mA 0.2 mA The battery temperature is monitored throughout the charging cycle for safety reasons. DS11889 - Rev 4 page 20/32 STBC03 Battery charger Figure 20. Charging flowchart Actions: * Pre-charge starts tPRE timer, starts charging in CC mode at IPRE DS11889 - Rev 4 * Fast-charge CC starts tFAST timer, increases charge current to IFAST * * Fast-charge CV activates the constant-voltage control loop Start alarm: the CHG pin starts toggling page 21/32 STBC03 Battery charger Figure 21. End-of-charge flowchart Figure 22. CC/CV charging profile (not in scale) Charger current Charger voltages VFLOAT Battery voltage VPRE IFAST Battery current IPRE IEND Time OFF PRE-CHARGE CC DS11889 - Rev 4 FAST-CHARGE OFF CV page 22/32 STBC03 Battery temperature monitoring 8.3 Battery temperature monitoring The STBC03 integrates all the needed blocks to monitor the battery temperature through an external NTC resistor. The battery temperature monitoring is enabled only during the battery charging process, in order to save power when the system is supplied from the battery. When the battery temperature is outside the normal operating range (0-45 C), the charging process is halted, an alarm signal is activated (the CHG pin toggles at 16.2 Hz) but the charging timeout timers are not stopped. If the temperature goes back to the normal operating range, before the maximum charging time has elapsed, the charging process is resumed and the alarm signal is cleared. In case of the charging timeout expires and the temperature is still outside the normal operating range, the charging process is stopped but it can be still restarted using the CEN pin. Both temperature thresholds feature a 3 C hysteresis. The battery temperature monitoring block is designed to work with an NTC thermistor having R25 = 10 k and = 3370 (Mitsubishi TH05-3H103F). If an NTC thermistor is not used, 10 k resistor must be connected to ensure the proper IC operation. 8.4 Battery overcharge protection The battery overcharge protection is a safety feature, active when a valid input voltage is connected, preventing the battery voltage from exceeding a VOCHG value. Should an overcharge condition be detected, the current path from the input to the battery is opened and a fault signal is activated (the CHG pin toggles at 8.2 Hz). When the battery voltage goes below VOCHG, normal operations can only be restarted by disconnecting and connecting back again the input voltage (VIN). 8.5 Battery over-discharge protection The battery over-discharge protection is a safety feature enabled only when no valid input voltage source (VUVLO < VIN < VINOVP) is detected. Therefore, when the STBC03 and the system are powered off from the battery, an over-discharge of the battery itself is avoided. Should the battery voltage level be below VODC for more than tODD (over-discharge state), the STBC03 turns off and current sunk from the battery is reduced to less than 50 nA. When a valid input voltage source is detected, while the battery is in an over-discharge state, the STBC03 charger, SYS and LDO outputs are enabled. This condition persists until the battery voltage has exceeded the over-discharge released threshold (VODCR), otherwise any other disconnection of a valid input voltage source brings back the STBC03 to a battery over-discharge state. 8.6 Battery discharge overcurrent protection When the STBC03 is powered off from the battery connected to the BAT pin, a discharge overcurrent protection circuit disables the STBC03 if the current sunk from the battery is in excess of IBATOCP (900 mA typical) for more than tDOD. The presence of a valid input voltage source or triggering the WAKE-UP input pin, allows normal operating conditions to be restored. 8.7 Battery fault protection The STBC03 features a battery fault protection. The STBC03 charger is stopped if the battery voltage remains below 1 V for at least 16 seconds. 8.8 Floating voltage adjustment The STBC03 features a floating voltage adjustment, controlled via the external resistor RFLOAT connected between battery and BATSNSFV. For safety reasons, the battery voltage overcharge threshold level (VOCHG) is linked to any floating voltage set. DS11889 - Rev 4 page 23/32 STBC03 Input overcurrent protection 8.9 Input overcurrent protection When the STBC03 is powered off from a valid input voltage source, a current limitation circuit prevents the input current from increasing in an uncontrolled manner in case of excessive load. In fact, when VSYS is lower than VILIMSCTH, the input current is limited so to have a reduced power dissipation. As soon as VSYS increases over VILIMSCTH, the input current limit value is increased to IINLIM. 8.10 SYS short-circuit protection, LDO current limitation In battery mode condition, if a short-circuit on the SYS pin happens, the STBC03 is turned off (no deglitch). This short-circuit protection occurs until the SYS voltage drops below VSCSYS. If the LDO output is in a short-circuit condition, the maximum delivered current is limited to ISC. 8.11 IN overvoltage protection Should the input voltage source temporarily be VIN>VINOVP (for example due to a poorly regulated voltage source), then the STBC03 is powered off from the battery, thus any load connected to SYS is protected. As soon as the input voltage source goes back within a valid input range (VUVLO < VIN < VINOVP), the STBC03 is then powered off again from VIN. 8.12 Shutdown mode Asserting the SD pin high forces the STBC03 to enter in shutdown mode (low power), the current sunk from the battery is reduced to less than 50 nA. Both SYS and LDO pins are not supplied. Normal operating conditions are restored either by connecting a valid input voltage source (VUVLO