STBC08 800mA Standalone linear Li-Ion Battery charger with thermal regulation Feature summary ■ Programmable charge current up to 800mA ■ No external MOSFET, sense resistors or blocking diode required ■ Complete linear charger for single cell lithiumion batteries ■ Constant current / constant voltage operation with thermal regulation to maximize charge rate without risk of overheating ■ Two charge status output pins ■ Charges single cell li-ion batteries directly from USB port ■ Preset 4.2V charge voltage with 1% accuracy ■ Charge current monitor for gas gauging ■ Automatic recharge ■ Under-voltage lockout ■ C/10 Charge termination ■ 25µA supply current in shutdown mode ■ Low battery voltage detect for precharge setting ■ Soft-start feature limits inrush current ■ DFN6 (3x3mm) package (for better power dissipation) Applications ■ Cellular telephones ■ PDAs ■ Bluetooth applications ■ Battery-powered devices DFN6 (3x3mm) Description The STBC08 is a constant current/constant voltage charger for single cell Li-Ion batteries. No external sense resistor or blocking diode is required. The STBC08 is designed to work within USB power specifications. An internal block regulates the current when the junction temperature increases, in order to protect the device when it operates in high power or high ambient temperature conditions. The charge voltage is fixed at 4.2V, and current limitation can be programmed using a single resistor connected between PROG pin and GND. The charge cycle is automatically terminated when the current flowing to the battery is 1/10 of the programmed value. If the external adaptor is removed, the STBC08 turns off and a 2µA current can flow from the battery to the device. The device can be put into Shutdown Mode, reducing the supply current to 25µA. The device also has a charge current monitor, under voltage lockout, automatic recharge. The charge termination and input voltage presence are indicated by two separate status pins. Order code Part number Package Packaging STBC08PMR QFN6 (3mm x 3mm) 4500 parts per reel September 2006 Rev. 1 1/17 www.st.com 17 STBC08 Contents 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.1 Charge cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2 VCC Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.3 Power ON pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.4 CHRG pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.5 PROG pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.6 Programming charge current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.7 BAT pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.8 Charge termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.9 Automatic recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.10 Soft start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.11 Thermal regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.12 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.13 Stability considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2/17 STBC08 Block diagram 1 Block diagram Figure 1. Block diagram 3/17 Pin configuration STBC08 2 Pin configuration Figure 2. Pin connections (top view) Table 1. Pin description Pln N° Symbol 1 BAT 2 CHRG 4 GND 5 PROG 6 VCC 4/17 This pin provides an accurate 4.2V output voltage and the charge current to the battery. Only 2µA reverse current can flow in to the device when in Shutdown mode Open Drain. When the STBC08 detects an undervoltage lockout condition or when the POWER ON external adaptor provide an input voltage higher than 7.2V or less than battery voltage, POWER ON goes in high impedance state 3 Figure 3. Note Open Drain. This pin goes in low impedance when the STBC08 is in precharge or charge mode Ground pin Charge current program. Charge Current monitor and shutdown pin. The current limitation is programmed using a 1% tolerance RPROG between PROG pin and GND Input supply voltage. The input range is from 4.25 to 6.5V. If VCC<VBAT+30mV the device enters Shutdown mode and the sinked IBAT is less than 2µA Application circuit STBC08 Maximum ratings 3 Maximum ratings Table 2. Absolute maximum ratings Symbol Parameter Value Unit From -0.3 to 10 V BAT pin voltage From -0.3 to VCC+0.3 V VPROG PROG pin voltage From -0.3 to VCC+0.3 V VCHRG CHRG pin voltage From -0.3 to 7 V POWER ON pin voltage From -0.3 to 7 V BAT pin current 800 mA PROG pin current 800 µA Input supply voltage Vcc VBAT VPOWER-OM IBAT IPROG BAT short circuit duration PD Power dissipation TJ Max junction temperature Continuous Internally Limited mW 125 °C TSTG Storage temperature range -65 to 125 °C TOP Operating junction temperature range -40 to 85 °C Table 3. Symbol RthJA Thermal Data Parameter Value Unit Thermal Resistance Junction-Ambient 105.7 °C/W 5/17 Electrical characteristics STBC08 4 Electrical characteristics Table 4. Electrical characteristics (VCC = 5V, CI = 1µF, TJ = -40 to 85° unless otherwise specified) (Note 2). Symbol VCC ICC Parameter Test Supply voltage IBAT BAT pin current IPRE Pre-charge current VPRE Pre-charge threshold VUV VCC Undervoltage lockout VMSD VASD Unit 6.5 V 150 500 Standby mode (charge terminated) 150 300 RPROG not connected 21 40 VCC < VBAT 17 50 VCC < VUV 17 40 4.158 4.2 4.242 V Current mode RPROG=10KΩ 90 100 110 mA Current mode RPROG=2KΩ 465 500 535 mA Standby mode VBAT=4.2V 0 -2.5 -6 µA Shutdown mode (RPROG not connected), TJ=25°C ±1 ±2 µA Sleep mode, VCC=0V, TJ=25°C ±1 ±2 µA VCC = 4.3V to 6.5V 20 45 70 mA RPROG =10KΩ VBAT falling 2.8 2.9 3.0 V Hysteresis RPROG =10KΩ 70 100 130 mV 3.65 3.80 3.95 V 50 180 300 mV PROG Pin Rising 1.15 1.21 1.30 PROG Pin Falling 0.85 0.95 1.05 VCC Low to High TJ=25°C RPROG =10KΩ 50 85 120 VCC High to Low TJ=25°C RPROG =10KΩ 5 VCC Low to High RPROG =10KΩ Hysteresis RPROG =10KΩ Manual shutdown threshold VCC-VBAT Lockout threshold µA VBAT<2.8V RPROG =2KΩ TJ=25°C V mV 30 C/10 Termination current threshold (IBAT/IBATC10) (Note 3) RPROG =10KΩ 0.1 ITERM RPROG =2KΩ 0.1 VPROG PROG pin voltage Current Mode RPROG =10KΩ VCHRG CHRG Pin pull-down voltage ICHRG=5mA IPOWER_ON POWER–ON pin leakage current Pull-up IPOWER_ON POWER–ON pin pull-down voltage IPOWER-ON=5mA 6/17 Max. Charge mode, RPROG =10KΩ Supply current (Note 1) Termination output voltage Typ. 4.25 Shutdown mode VBAT Min. 50 mA/mA 0.93 1.0 1.07 V 0.35 0.6 V 1 µA 0.6 V 0.35 STBC08 Table 4. Electrical characteristics Electrical characteristics (VCC = 5V, CI = 1µF, TJ = -40 to 85° unless otherwise specified) (Note 2). Symbol Parameter Test Min. Typ. Max. Unit Recharger battery threshold Battery Voltage TJ=25°C voltage RPROG =10KΩ 200 mV TLIM Junction temperature in constant temperature mode 120 °C RON Power Fet “ON” resistance (Between VCC and BAT) 600 mΩ tSS Soft-start time IBAT=0 to IBAT=1000V/RPROG 100 µs Recharge comparator filter time Note 4 VBAT High to Low 0.75 2 4.5 ms tTERM Termination comparator filter time Note 4 IBAT Falling Below ICHG/10 400 1000 2500 µs IPROG PROG pin pull-up current ∆VRECHRG TRECHARGE Note: 1 µA 1 Supply current includes PROG pin current but not any current delivered to the battery through the VBAT pin. 2 The STBC08 was tested using a battery simulator and an output capacitor value of 4.7µF 3 ITERM is expressed as a fraction of measured full charge current with indicated PROG resistor 4 Guaranteed by design 7/17 Typical performance characteristics STBC08 5 Typical performance characteristics Figure 4. IBAT vs Supply voltage Figure 5. VBAT vs VCC Figure 6. IBAT vs temperature Figure 7. VPROG vs temperature Figure 8. IBAT/IPROG vs temperature Figure 9. Recharge battery threshold voltage vs. temperature 8/17 STBC08 Typical performance characteristics Figure 10. IBAT/IPROG vs VCC Figure 11. IBAT vs VBAT Figure 12. VCHRG vs temperature (CHRG pin output low voltage) Figure 13. IBAT vs VPROG Figure 14. Power FET “ON” resistance 9/17 Application information 6 STBC08 Application information The STBC08 uses an internal P-Channel MOSFET to work in constant current and constant voltage method. It is able to provide up to 800mA with a final regulated output voltage of 4.2V ± 1% in full temperature range. No blocking diode and sensing resistor are required. It is also possible to use an USB port as power supply voltage. 6.1 Charge cycle A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold level, the RPROG program resistor of 1% is connected between the PROG pin to GND pin and when a battery is connected to the charger output. If the battery voltage is below 2.9V, the charger enters Trickle Charge mode. In this condition, the device supplies 1/10 of the programmed charge current to bring the battery voltage up to safe level otherwise the life of a battery is reduced. If the BAT pin voltage is higher than 2.9V the charger enters in Constant Current Mode. When the BAT pin voltage is close to the final float voltage (4.2V) the device enters in Constant Voltage Mode and the charge current begins to decrease. The charge cycle is terminated when the current drops to 1/10 of the programmed value. 6.2 VCC Pin Input Supply Voltage. This pin is used to supplie the device in the range from 4.25V to 6.5V voltage. A bypass capacitor of 1µF is recommended for use. When VCC value drops of 30mV of the BAT pin voltage, the device enters in Shutdown Mode, dropping IBAT to less than 2µA. 6.3 Power ON pin The POWER ON pin is an open drain flag that indicates VCC presence, VUVLO<VCC<7.2V and VCC>VBAT. While in high impedance indicates that VCC< VUVLO, VCC>7.2V or VCC<VBAT. In high impedance status the VCC is insufficient to start the charge cycle. 6.4 CHRG pin The CHRG pin is an open drain flag, it indicates the status of the charge. When the pin is in low state, the device is charging the battery. If the pin is in high impedance state the charge is terminated. Table 5. CHRG CHRG LOW HIGH LOW 00 01 HIGH - 11 Power-ON Table 5 describes Flag Status values for the CHRG pin. 10/17 STBC08 Application information -00 is Precharge Mode (Trickle charge mode) or Charge Mode. VCC is higher than VUVLO and RPROG is connected to the PROG pin. - 01 is STANBY MODE (charge completed) or SHUTDOWN MODE (RPROG not connected). - 11 supply is not sufficient. 6.5 PROG pin Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is programmed by connecting a 1% resistor, RPROG, to ground. When the device is charging in constant current, the value of voltage on this pin is 1.0V. In other conditions, the voltage on this pin can be used to measure the charge current using the following formula: IBAT = (VPROG/RPROG)*1000 The PROG pin is used to shut down the device, disconnecting the program resistor from ground a 1µA current flows to pull the PROG pin high. If the value of this Pin is 1.21V (shutdown threshold voltage), the device enters Shutdown mode and the input supply current drops to 25µA. Driving this pin to voltage beyond 2.4V a current of 35µA flows into the device from PROG pin. 6.6 Programming charge current The RPROG resistor is used to set the charge current value. The battery charge current is 1000 times the Prog pin current value. The program resistor and the charge current are calculated using the following formula: RPROG=1000*VPROG/IBAT; The charge current out of the BAT pin can be monitored through the PROG pin voltage using the following equation: IBAT=(VPROG/RPROG)x1000 6.7 BAT pin Charge Current Output pin. It provides charge current to the battery and regulates the final float voltage to 4.2V. An internal precision resistor is used as a feedback loop to compare the VO with the reference. 6.8 Charge termination A charge cycle is terminated when the final float voltage is reached consequently the charge current falls to 1/10th of the programmed value. The charge is over when the PROG pin voltage falls below 100mV for longer time than tTERM (~1ms). The charge current is latched off, the device enters in standby mode and the input supply current drops to 200µA. 11/17 Application information 6.9 STBC08 Automatic recharge The device restarts the charge cycle when the battery voltage falls below 4.05V to maintain the battery capacity value higher than 80%. During the recharge time, the CHRG pin goes low state. 6.10 Soft start When a charge cycle starts, a internal soft start circuit minimizes the inrush current. At starting phase, the charge current ramps from zero to the full scale in a 100µs period time. 6.11 Thermal regulation An internal thermal feedback loop reduces the output current if the die temperature attempts to rise above a present value of approximately 120°C. This feature protects the device from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the device. 6.12 Power dissipation It is very important to use a good thermal PC board layout to maximize the available output current. The thermal path for the heat generated by the IC is from the die to the copper lead frame through the package leads and exposed pad to the PC board copper. The PC board copper is the heat sink. The footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. Feed through vias to inner or backside copper layers are also useful in improving the overall thermal performance of the device. Other heat sources on the board, not related to the device, must also be considered when designing a PC board layout because they will affect overall temperature rise and the maximum output current. 6.13 Stability considerations The STBC08 contains two control loops: constant voltage and constant current. The constant-voltage loop is stable without any compensation when a battery is connected with low impedance leads. Excessive lead length, however, may add enough series inductance to require a bypass capacitor of at least 1µF from BAT to GND. Furthermore, a 4.7µF capacitor with a 0.2Ω to 1Ω series resistor from BAT to GND is required to keep ripple voltage low when the battery is disconnected. 12/17 STBC08 7 Package mechanical data Package mechanical data In order to meet environmental requirements, ST 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 ST trademark. ECOPACK specifications are available at: www.st.com. 13/17 Package mechanical data STBC08 DFN6 (3x3) MECHANICAL DATA mm. inch DIM. MIN. TYP MAX. MIN. TYP. MAX. A 0.80 0.90 1.00 0.031 0.035 0.039 A1 0 0.02 0.05 0 0.001 0.002 A3 0.20 0.008 b 0.23 0.30 0.38 0.009 0.012 0.015 D 2.90 3.00 3.10 0.114 0.118 0.122 D2 2.23 2.38 2.48 0.088 0.094 0.098 E 2.90 3.00 3.10 0.114 0.118 0.122 E2 1.50 1.65 1.75 0.059 0.065 0.069 e L 0.95 0.30 0.40 0.037 0.50 0.012 0.016 0.020 7946637A 14/17 STBC08 Package mechanical data Tape & Reel QFNxx/DFNxx (3x3) MECHANICAL DATA mm. inch DIM. MIN. TYP A MAX. MIN. TYP. 330 13.2 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T MAX. 0.504 0.519 18.4 0.724 Ao 3.3 0.130 Bo 3.3 0.130 Ko 1.1 0.043 Po 4 0.157 P 8 0.315 15/17 Revision history STBC08 8 Revision history Table 6. Revision history Date Revision 04-Sep-2006 1 16/17 Changes Initial release. STBC08 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 herein 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 assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. 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