SY6981QDC

Application Note: SY6981 High Efficiency, 1.2A Two-cell Boost Li-Ion Battery Charger General Description Features SY6981 is a 3.6-5.5VIN, 1.2A two-cell synchronous Boost Li-Ion battery charger which integrates 1MHz switching frequency and full protection functions. The charge current up to 1.2A can be programmed by using the external resistor for different portable applications and indicates the charger current information simultaneously. It also has a programmable charge timeout for safety battery charge operation and a programmable input voltage threshold for adaptive input current limit. SY6981 can disconnect output when there is an output short circuit or shutdown. It consists of 18V rating FETs with extremely low on resistance to achieve high charge efficiency and simple peripheral circuit design. Low Profile QFN3×3 Package Integrated Synchronous Boost with 18V Rating Low RDSON FETs for High Charge Efficiency Trickle Current / Constant Current / Constant Voltage Charge Mode Programmable Input Voltage Threshold for Adaptive Current Limit. Maximum 1.2A Constant Charge Current Charge Current Information Indication. Programmable Charge Timeout Programmable Constant Charge Current Selectable Constant Voltage ±0.5% Battery Voltage Accuracy Thermal Regulation Protection External Shutdown Function Input Voltage UVLO and OVP Over Temperature Protection Output Short Circuit Protection Charge Status Indication Normal Synchronous Boost Operation When the Battery is Removed SY6981 along with small QFN3×3 footprint provides small PCB area application. Ordering Information SY6981 □(□□ □□)□ □□ □ Applications Tempera ture Code Packa ge Code Optiona l Spec Code Ordering Number SY6981QDC Package type QFN3×3-16 Cellular Telephones, PDA, MP3 Players, MP4 Players Digital Cameras Bluetooth Applications PSP Game Players, NDS Game Players Notebook Note Typical Applications CBD CBST BST BD L INPUT Sync FET LX Block FET Charge Pump Main FET DIND Battery Charge Control & Protection Logic Csvin COUT Li-Ion Battery RNTC NTC SY6981 SVIN RNOR BAT ICHG TIM CTIM RICHG CICHG EN STAT SVIN Rup CV2 CV1 Low/Floating High/Low SGND/ PGND VSEN Rdown Figure1. Schematic Diagram AN_SY6981 Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 1 AN_SY6981 Pinout (top view) Name STAT CV2 TIM NTC CV1 VSEN EN SGND ICHG BD BST BAT LX PGND SVIN STAT CV2 TIM NTC CV1 VSEN 1 2 3 4 5 6 SVIN 16 7 EN PGND 15 8 SGND LX 14 9 ICHG BD 13 10 BD BAT 12 11 BST (QFN3×3-16) Top Mark: cRxyz, (Device code: cR, x=year code, y=week code, z= lot number code) Pin Number Description Charge status indication pin. It is open-drain output pin and pulled high to SVIN through 1 a LED to indicate the charge in process. When the charge is done, the LED will be off. Battery CV voltage selection pin. Program 4 different CV thresholds by setting different 2 voltage on this pin and pin5. Floating or grounding this pin in the application. CV2 pin can’t be pulled high to any bias voltage higher than 3.3V. Charge time limit pin. Connect this pin with a capacitor to ground. Internal current source 3 charge the capacitor for TC mode and CC mode’s charge time limit. TC charge time limit is about 1/9 of CC charge time. Thermal protection pin. UTP threshold is typical 76% of VSVIN and OTP threshold is typical 30.5% of VSVIN. Pull up to SVIN can disable charge logic and make the IC operate 4 as a normal Boost regulator. Pull down to ground can shut down the IC. Battery CV voltage selection pin. Program 4 different CV thresholds by setting different 5 voltage on this pin and pin2. The detailed information is shown in description section. Voltage sense of SVIN. If the voltage drops to internal 1.195V reference voltage, the 6 SVIN will be clamped to setting value and input current will be limited. 7 Enable control pin. High logic for enable on, and low logic for enable off. 8 Signal ground pin. Charge current program pin. Pull down to GND with a resistor RICHG. The mirror current about 1/10000 of the blocking FET current will dump into the external RC network 9 through ICHG pin and compared to the internal reverence 1V. So ICC = (1V/ RICHG) ×10000, ITC = (1V/ RICHG)×1000+0.02. Connect it to the drain of internal blocking FET. Bypass at least a 4.7µF ceramic cap to 10, 13 GND. Boost-strap pin. Supply rectified FET’s gate driver. Decouple this pin to LX with a 0.1µF 11 ceramic cap. 12 Battery positive pin. 14 Switch node pin. Connect it to the external inductor. 15 Power ground pin. Analog power input pin. Connect a MLCC from this pin to ground to decouple high 16 harmonic noise. This pin has OVP and UVLO function to make the charger operate within safe input voltage range. AN_SY6981 Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 2 AN_SY6981 Absolute Maximum Ratings (Note1) STAT, NTC, CV1, VSEN, EN, ICHG, BD, BAT, LX, SVIN ------------------------------------------------------------ 18V CV2, TIM, BST-LX -------------------------------------------------------------------------------------------------------------- 4V LX Pin Continuous Current ------------------------------------------------------------------------------------------------------ 5A Power Dissipation, PD @ TA = 25°C, QFN3×3 ---------------------------------------------------------------------------- 2.6W Package Thermal Resistance (Note2) θ JA ------------------------------------------------------------------------------------------------------------------- 38°C/W θ JC --------------------------------------------------------------------------------------------------------------------- 4°C/W Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------------- 260°C Storage Temperature Range ------------------------------------------------------------------------------------- -65°C to 125°C Recommended Operating Conditions (Note3) SVIN -------------------------------------------------------------------------------------------------------------------- 3.6V to 5.5V STAT, NTC, CV1, VSEN, EN, ICHG, BD, BAT, LX, -------------------------------------------------------- -0.3V to 16V CV2, TIM, BST-LX ------------------------------------------------------------------------------------------------ -0.3V to 3.3V LX Pin Continuous Current ---------------------------------------------------------------------------------------------------- 5A Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------ -40°C to 85°C AN_SY6981 Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 3 AN_SY6981 Electrical Characteristics TA=25°C, VIN=5V, GND=0V, CIN=4.7µF, L=0.68µH, RICHG=10kΩ, CTIM=470nF, unless otherwise specified. Parameter Bias Supply (VSVIN) Supply Voltage Symbol Conditions VSVIN VSVIN Under Voltage Lockout Threshold VUVLO VSVIN Under Voltage Lockout Hysteresis ∆VUVLO Input Over Voltage Protection VOVP Input Over Voltage Protection Hysteresis Quiescent Current ∆VOVP Battery Discharge Current IBAT Input Quiescent Current IIN Oscillator and PWM Switching Frequency fSW Main N-FET Minimum Off Time tMIN_OFF Main N-FET Maximum Off Time Main N-FET Minimum On Time Min Typ 3.6 VSVIN rising and measured from VSVIN to GND Measured from VSVIN to GND VSVIN rising and measured from VSVIN to GND Measured from VSVIN to GND Max Unit 16 V 3.6 V 100 mV 5.8 V 0.5 Shut down IC, EN=NTC=0 Disable charge, EN=1,NTC=0 V 10 µA 1.5 mA 1000 kHz With 18V rating 100 ns tMAX_OFF With 18V rating 30 µs tMIN_ON With 18V rating 100 ns Power MOSFET RDS(ON) of Main N-FET RNFET_M 100 mΩ RDS(ON) of Rectified N-FET RNFET_R 50 mΩ RDS(ON) of Blocking N-FET RNFET_B 50 mΩ Voltage Regulation Battery Charge Voltage VBAT_REG High Level Logic for CV1 VCV_H Low Level Logic for CV1,CV2 VCV_L Recharge Threshold Refer to VBAT_REG Trickle Current Charge Mode Battery Voltage Threshold AN_SY6981 Rev. 0.9 VCV1>1.5V, VCV2 is floating VCV11.5V, VCV2