SY6924QDC

Application Note: SY6924 High Efficiency, 2.5A, Multi-Cell Li-Ion Battery Charger General Description Features SY6924 is a 4-14V input, 2.5A multi-cell Li-Ion battery step-down charger. The charge current up to 2.5A can be programmed by using the external resistor for different portable applications. It also has a programmable charge timeout and adaptive input power limit for safety battery charge operation. It consists of 16V rating reverse blocking FET and power switching FETs with extremely low ON resistance to achieve high charge efficiency and simple peripheral circuit design. SY6924 along with small QFN3×3 footprint provides small PCB area application. Ordering Information SY6924 □(□□ □□)□ □□ □ Tempera ture Code Packa ge Code Optiona l Spec Code Ordering Number SY6924QDC Package type QFN3×3-16 Integrated Synchronous Buck and Reverse Blocking FET with 16V Rating Adaptive Input Power Limit for 4-14V Wide Input Voltage Maximum 2.5A Programmable Charge Current 4.2V and 4.35V Constant Voltage Selectable +/-0.5% Cell Voltage Accuracy Support Single-cell or Two-cell Battery Pack External Shutdown Function Input Voltage UVLO and OVP Thermal Fold-back Protection Over Temperature Protection Battery Short Protection Programmable Charge Timeout Charge Status Indication Low Profile QFN3×3 Package for Portable Applications Applications Note Power Bank Cellular Telephones, PDA, MP3 Players, MP4 Players PSP Game Players, NDS Game Players Notebook Typical Applications Figure1. Schematic Diagram AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. AN_SY6924 Pinout (top view) (QFN3×3-16) Top Mark: Ynxyz, (Device code: Yn, x=year code, y=week code, z= lot number code) Pin Name Pin Number RS 1 CELL 2 TIM 3 NTC 4 CV 5 VSEN 6 EN 7 SGND 8 AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Description Charge current sense resistor positive pin. The sensed voltage drop between RS and BAT is used for charge current regulation and charge termination detection. Battery voltage selection pin. Floating for two cells battery and grounding for single cell battery. CELL pin can’t be pulled high to any bias voltage higher than 3.3V. Charge time-out programming pin. Connect this pin with a capacitor to ground to program the time-out protection threshold. Internal current source charge the capacitor for TC mode and fast charge (CC&CV) mode’s charge time limit. TC charge time limit is about 1/9 of fast charge time. Battery thermal sense pin. The voltage on the NTC pin is sensed for battery thermal protection. UTP threshold is typical 75% of VIN and OTP threshold is typical 45% of VIN. NTC pin also can be used for the adaptive input power limit reference refresh. The adaptive input power limit threshold will be refreshed when NTC is pulled low for more than 100ms. SY6924 sets the charge current to the trickle value; the IC will refresh the adaptive input power limit threshold according the input voltage. For higher than 6V input, the IC will clamp the input voltage at VIN-0.6V by regulating the duty cycle of Buck converter. For lower than 6V input, the clamped input voltage is set by VSEN pin. Battery CV voltage selection pin. Input voltage sense pin for adaptive input power limit. If the voltage drops to internal 1.19V reference voltage, the VIN will be clamped to setting value and input current will be limited. Enable control pin. High logic for enable on and low logic for enable off. Signal ground pin. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. AN_SY6924 STAT 9 BD 10, 13 BST 11 IN 12 LX PGND BAT 14 15 16 Charge status indication pin. Open drain pin. Pull high to IN thru a LED to indicate the charge in process. When the charge is done, LED is off. Connect to the drain of internal blocking FET. Bypass at least a 10µF ceramic cap to GND. Boot-strap pin. Supply main FET’s gate driver. Decouple this pin to LX with a 0.1µF ceramic cap. DC power input pin. Connect a MLCC from this pin to ground to decouple high harmonic noise. This pin has OVP and UVLO function to make the charger operate within safe input voltage area. Switch node pin. Connect to external inductor. Power ground pin. Battery voltage sense pin. Absolute Maximum Ratings (Note 1) IN, BAT, LX, NTC, STAT, BD, EN, CV, VSEN -------------------------------------------------------------------------- 18V TIM, CELL------------------------------------------------------------------------------------------------------------------------- 4V BST-LX Voltage ------------------------------------------------------------------------------------------------------------------ 4V RS ------------------------------------------------------------------------------------------------------------- BAT-0.3~BAT+0.3V LX Pin Current Continuous ------------------------------------------------------------------------------------------------------ 5A Power Dissipation, PD @ TA = 25°C, QFN3×3----------------------------------------------------------------------------- 2.1W Package Thermal Resistance (Note 2) θ JA ------------------------------------------------------------------------------------------------------------------- 48 °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 150°C Recommended Operating Conditions (Note 3) IN -------------------------------------------------------------------------------------------------------------------------- 4V to 14V BAT, LX, NTC, STAT, BD, EN, CV, VSEN--------------------------------------------------------------------------0V to16V TIM, CELL--------------------------------------------------------------------------------------------------------------- 0V to 3.3V BST-LX Voltage -------------------------------------------------------------------------------------------------------- 0V to 3.3V RS ---------------------------------------------------------------------------------------------------------- BAT-0.25~BAT+0.25V LX Pin Current Continuous --------------------------------------------------------------------------------------------------- 4.5A Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 100°C Ambient Temperature Range ------------------------------------------------------------------------------------ -40°C to 85°C AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. AN_SY6924 Electrical Characteristics TA=25°C, VIN=5V, GND=0V, CIN=10µF, L=2.2µH, RS=10mΩ, CTIM=330nF, unless otherwise specified. Parameter Bias Supply (VIN) Supply Voltage Operation Range Input Voltage Lockout Threshold Input Voltage Lockout Hysteresis Input Over Voltage Protection Input Over Voltage Protection Hysteresis Quiescent Current Battery Discharge Current Input Quiescent Current Oscillator and PWM Switching Frequency Power MOSFET RDS(ON) of Main N-FET RDS(ON) of Rectified N-FET RDS(ON) of Blocking N-FET Voltage Regulation Battery Charge Voltage Symbol VIN ∆VOVP IBAT IIN VIN absent or EN=Low Disable charge ∆VUVLO VIN_OVP Min Typ 4 VIN rising and measured from IN to ground Measured from IN to ground VIN rising and measured from IN to ground Measured from IN to ground VUVLO Max Unit 14 V 4 V 0.2 V V 13.5 0.5 5 0.8 V 10 1.1 µA mA fSW 500 kHz RNFET_M 30 mΩ RNFET_R RNFET_B 55 45 mΩ mΩ VBAT_REG Recharge Threshold Refer to ∆VRCH VBAT_REG Trickle Charge Rising Edge VTRK Threshold Adaptive Input Current REF Modify NTC Voltage Threshold for Adaptive Input Current VNTC Reference Refresh NTC Low Time to Enable the tDET Adaptive Input Current Refresh Charge Current Charge Current Accuracy for ICC Constant Current Mode Charge Current Accuracy for ITC Trickle Current Mode Termination Current ITERM Output Voltage OVP Output Voltage OVP Threshold VO_OVP Adaptive Input Power Limit Reference Reference for Adaptive Input VSEN Power Limit The Adaptive Input Power ∆VAICL Limit Reference is VIN-∆VAICL AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Conditions 1-cell battery, VCV1.5V 2-cell battery, VCV1.5V 1-cell battery 2-cell battery 1-cell battery 2-cell battery NTC falling edge 4.179 4.328 8.358 8.656 50 100 2.7 5.4 4.2 4.35 8.4 8.7 100 200 2.8 5.6 4.221 4.371 8.442 8.744 150 300 2.9 5.8 0.4 Low pulse width mV V V 100 ms ICC=25mV/RS -10% 10% ITC=2.5mV/RS -50% 50% ITERM=2.5mV/RS -50% 50% NTC pull low than 100ms and VIN is higher than 6V V 105% 110% 115% VBAT_REG 1.16 1.19 1.22 V 600 mV Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. AN_SY6924 Timer Trickle Current Charge tTC Timeout Constant Current Charge tCC Timeout Charge Mode Change Delay tMC Time Termination Delay Time tTERM Recharge Time Delay tRCHG Short Circuit Protection Output Short Protection VSHORT Threshold, Falling Edge Auto Shut Down Auto Shutdown Voltage VASD Threshold Auto Shutdown Voltage ∆VASD Threshold Hysteresis Logical Control High Level Logic for Enable VENH Control Low Level Logic for Enable VENL Control High Level Logic for CV VCVH Low Level Logic for CV VCVL Battery Thermal Protection NTC Under Temperature Protection VNTC_UTP Under Temperature Protection VNTC_UTP_HYS Hysteresis Over Temperature Protection VNTC_OTP Over Temperature Protection VNTC_OTP_HYS Hysteresis Thermal Fold-back and Thermal Shutdown Thermal Fold-back Threshold TFold Thermal Fold-back Hysteresis TFoldHYS Falling Edge Thermal Fold-back Ratio IFold Thermal Shutdown TSD Temperature Thermal Shutdown TSDHYS Temperature Hysteresis VIN fall, measured from IN to BAT VIN rise, measured from IN to BAT 0.36 0.5 0.64 hour 3.5 4.5 5.5 hour 30 ms 30 30 ms ms 1.7 2.00 2.3 40 110 180 mV 65 1.5 V 0.4 V 0.4 V V 1.5 74% Falling edge Rising threshold 75% 76% 5% 44% Rising edge V 45% 46% VIN 1.5% 120 ºC 20 ºC 0.25 ICC 160 ºC 30 ºC Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 2: θ JA is measured in the natural convection at TA = 25°C on a low effective four-layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. AN_SY6924 Typical Performance Characteristics (TA=25°C, VIN=5V, VBAT=3.6V for single-cell battery application. VIN=9V, VBAT=7.6V for two-cell battery application. Rs=10mΩ, CTIM=330nf, unless otherwise specified.) Efficiency vs. Load Current 99 98 97 96 Single Cell Battery 95 Two Cell Battery 94 0 0.5 1 1.5 2 2.5 3 Charge Current (A) Steady Waveforms (Two cells battery, CV Mode) CH1:VIN CH2:VLX CH3:VBAT CH4:IL VBAT 5V/div VIN 5V/div IL VLX 2A/div 10V/div Time (4us/div) AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. AN_SY6924 Steady Waveforms Steady Waveforms (TC Mode) (Short Mode) VIN CH1:VIN CH2:VLX CH3:VBAT CH4:IL 2V/div VBAT 2V/div VSTAT 5V/div IL 1A/div IL VIN 1A/div 2V/div IL 2A/div VLX 2V/div CH1:VIN CH2:VBAT CH3:VSTAT CH4:IL VBAT 2V/div Time (4us/div) Time (200ms/div) Steady Waveform When No Battery Steady Waveform (NTC=50% VIN，No battery) (NTC=50% VIN,100mA load to BAT,VBAT=3V) CH2: VBAT CH3: VSTAT CH4: IL CH2: VBAT CH3: VSTAT CH4: IL VSTAT 10V/div VSTAT 10V/div VBAT 5V/div IL 0.5A/div VBAT IL 5V/div 0.5A/div Time (100ms/div) Time (100ms/div) Power On Soft Start (Two Cell Battery) CH1: VIN CH2: VSTAT CH3: VBAT CH4:IBAT (Two Cell Battery) CH1: VIN CH2: VLX CH3: VBAT CH4: IL VBAT 5V/div VBAT 5V/div VIN 5V/div VIN 5V/div VSTAT 10V/div IL 2A/div IBAT 2A/div Time (200ms/div) AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. VLX 10V/div Time (4ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 7 All Rights Reserved. AN_SY6924 Low Pulse On NTC Pin Adaptive Input Power Limit Reference Refresh (VIN=9V VBAT=7.6V ) CH1: VIN CH2: VNTC CH3: VBAT CH4:IBAT (Input Adapter changes to 7V/1A VBAT=3.6V ) CH1: VIN CH2:VNTC CH3: VBAT CH4:IBAT VBAT VIN IBAT VNTC 5V/div 5V/div VIN 2V/div IBAT 1A/div 5V/div 2A/div 5V/div Time (200ms/div) AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. VBAT VNTC 2V/div Time (400ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 8 All Rights Reserved. AN_SY6924 General Function Description SY6924 is a 4V-14V input, 2.5A step-down multicell Li-Ion battery charger, which integrates reverse blocking FET, 500 kHz synchronous buck and full protection functions. The charge current up to 2.5A can be programmed by using the external resistor for different portable applications. It also has a programmable charge timeout and adaptive input power limit for safety battery charge operation. It consists of 16V rating FETs with extremely low ON resistance to achieve high charge efficiency and simple peripheral circuit design. Charging Status Indication Description STAT is an open drain pin and a pull up resistor is needed for charging status indication. Connect a LED from IN to STAT pin, LED ON means Charge-inProcess, LED OFF means Charge Done, LED Flashing with 1.3Hz means Fault Mode. 1. Charge-In-Process – Pull and keep STAT pin to Low; 2. Charge Done – Pull and keep STAT pin to High; 3. Fault Mode – Output high and low voltage alternatively with 1.3Hz frequency. The faults include input OVP, BAT OVP, BAT short, BAT UTP, BAT OTP, time-out and thermal shutdown. Switching Mode Buck Charger Basic Operation Description Switching Mode Control Strategy SY6924 utilizes quasi-fixed frequency control to simplify the internal close-loop compensation design. The quasi-fixed frequency settled at 500 kHz is easy for the size minimization of peripheral circuit design. During the light load operation, the OFF time of the main switch is going to be stretched to achieve frequency fold back. Operation Principle SY6924 works as a synchronous Buck mode battery charger when the adapter is present. It utilizes 500 kHz switching frequency to minimize the PCB design. The charger will operate in battery short mode, trickle charge mode, constant current charge mode and constant voltage charge mode according to the battery voltage. The charge current in every mode is showed in following charge curve. In constant voltage mode, if charge current is lower than termination current, the charger will stop charging until battery voltage drops to recharge voltage. AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. 4.2/8.4V Battery Voltage 2.8/5.6V 2V t ICC 2.5A Charge Current ICC/10 ≈50mA t BAT short Trickle charge Constant current charge Constant voltage charge Basic Adaptive Input Power Limit Principle SY6924 can limit the input power adaptively and adjust this threshold according the input voltage. It will automatically decrease charge current when IN voltage drops to adaptive input power limit reference VREF. For typical 5V adapter, VREF is set by VSEN pin, that is calculated as： VREF =1.19 × R UP +R DN R DN If IN voltage is higher than 6V, VREF is calculated as: VREF =VIN -∆VAICL Where, ∆ VAICL is 0.6V typically. VIN is the input voltage when adapter insert. VREF can be modified after a more than 100ms low pulse on NTC pin if the adapter is always present. When NTC is pulled low, the charge current is set to the trickle value; battery thermal protection and adaptive input power limit function are disabled. Full Charger Protections Description In charge mode, SY6924 has full protection to protect the IC and the battery. Input Over Voltage Protection – SY6924 has IN over voltage protection. It will turn off switching charger when input OVP occurs. IC will auto recover normal operation when fault removes. Silergy Corp. Confidential- Prepared for Customer Use Only 9 All Rights Reserved. AN_SY6924 BAT Over Voltage Protection – SY6924 will stop charging when BAT OVP occurs. The IC will auto recover normal operation when fault removes. Timeout Protection – The charger can detect a bad battery. It will stop charge and latch off when the charger works over safety time which is set by CTIM. Only recycling the input can release this fault. 1. 2. 3. 4. R2= 5. Battery Thermal Protection – When NTC voltage is lower than OTP threshold and higher than 0.4V or higher than UTP threshold, the converter will stop switching. IC will auto recovery when fault removes. Thermal Shutdown Protection – The IC will stop operation when the junction temperature is higher than 160°C. It will auto recover normal when fault removes. Applications Information Define KUT, KUT =74~76% Define KOT, KOT =44~46% Assume the resistance of the battery NTC thermistor is RUT at UTP threshold and ROT at OTP threshold. Calculate R2, KOT(1-KUT)RUT-KUT(1-KOT)ROT KUT-KOT Calculate R1 R1=(1/KOT-1)(R2+ROT) If choose the typical values KUT =75% and KOT=45%, then R2=0.375RUT-1.375ROT R1=1.222(R2+ROT) SY6924 accepts flexible NTC divider circuits. For below method, R1 and R2 can be calculated by below equations. Because of the high integration of SY6924, the application circuit based on this regulator IC is rather simple. Only input capacitor CBD, output capacitor COUT, inductor L, NTC resistors R1, R2, charging current sense resistor Rs and timer capacitor CTIM need to be selected for the targeted applications specifications. NTC Resistor: SY6924 monitors battery temperature by measuring the input voltage and NTC voltage. The controller triggers the UTP or OTP when the ratio K (K= VNTC/VIN) reaches the threshold of UTP (KUT) or OTP (KOT). The temperature sensing network is showed as below. Choose R1 and R2 to program the proper UTP and OTP points. R2= ROT × RUT × (KUT-KOT) KOT × KUT × (ROT-RUT)+RUT × KOT-ROT × KUT R1= R2 × RUT × (1-KUT) KUT × (R2+RUT) If choose the typical values KUT =75% and KOT=45%, then 0.3RUT × ROT 0.1125 × RUT-0.4125 × ROT R2 × RUT R1= 3(RUT+R2) R2= Charging Current Sense Resistor Rs The charging current sense resistor RS is calculated as below: RS = The calculation steps are: AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. 25mV , ICC Unit: mΩ Where the ICC is the battery constant charging current, unit: A. Silergy Corp. Confidential- Prepared for Customer Use Only 10 All Rights Reserved. AN_SY6924 Timer Capacitor CTIM The charger also provides a programmable charging timer. The charging time is programmed by the capacitor connected between the TIM pin and GND. The capacitance is given by the formula: Unit: F CTIM=2×10-11 S×TCC, TCC is the permitted fast charging time, unit: s. Input Capacitor CBD The ripple current through input capacitor is greater than ICBD _MIN = ICC D(1 − D) To minimize the potential noise problem, place a typical X7R or a better grade ceramic capacitor really close to the BD and GND pins. Care should be taken to minimize the loop area formed by CBD, and BD/GND pins. Output Capacitor COUT The output capacitor is selected to handle the output ripple noise requirements. Both steady state ripple and transient requirements must be taken into consideration when selecting this capacitor. For the best performance, it is recommended to use X7R or better grade ceramic capacitor with 10µF capacitance. Output Inductor L There are several considerations in choosing this inductor. 1) Choose the inductance to provide the desired ripple current. It is suggested to choose the ripple current to be about 40% of the average charge current. The inductance is calculated as: VOUT × (1-VOUT/VIN,MAX) L= FSW × IOUT,MAX × 40% Where FSW is the switching frequency and IOUT,MAX is the maximum load current. SY6924 is quite tolerant of different ripple current amplitude. Consequently, the final choice of inductance can be slightly off the calculation value without significantly impacting the performance. 2) The saturation current rating of the inductor must be selected to be greater than the peak inductor current under full load conditions. VOUT × (1-VOUT/VIN，MAX) ISAT,MIN>IOUT,MAX+ 2 × FSW × L 3) The DCR of the inductor and the core loss at the switching frequency must be low enough to AN_SY6924 Rev. 0.9A © 2018 Silergy Corp. achieve the desired efficiency requirement. It is desirable to choose an inductor with DCR