Fast Charging Technology The technology of lithium battery for mobile phones has reach a bottleneck, in order to speed up the battery charging speed, designers have to work on the charging power. Since Power = Voltage x Current, it means that the charging power can be improved by changing the design of both voltage and current. Currently the protocol launched by Qualcomm and MediaTek respectively for fast charging is based on the variable DC voltage mode. Yet, since the charging speed of the fast charging will eventually become slower, in order to prevent the battery from overshoot and other side effect, trickle charging will be applied. Charging Rate (%) 4.2V‐4.0V 20% Fast Charging Original Charging 4.0V‐3.5V 70% 3.5V↓ 10% Minutes The charging speed of fast charging is 45%-75% faster than the original charging. The Quick Charge 2.0 protocol launched by Qualcomm and the Pump ExpressTM protocol launched by MediaTek are the pioneers of this fast charging technology. Recently PI, Dialog, Leadtrend etc. are launching fast charging adaptor solutions based on these protocols. Quick Charge 2.0 VS Pump ExpressTM Quick Charge 2.0 and MTK Pump ExpressTM are the two common fast charging protocols in the industry. Below is the comparison between these two protocols. Quick Charge 2.0 Pump ExpressTM Company Qualcomm MediaTek Performance Charging speed 75% faster Charging speed 45% faster Additional Accessories High cost (integration of hard/software) Phone side: Same cost, through USB PHY Charger side: Add new IC for communication Low Cost (software improvement) Phone side: PMIC needs to support load modulation Charger side: load modulation integrated into IC Original Solution PI (Solution SC1209K) Dialog ( Solution IW1760) Dialog (Solution IW1680) Leadtrend (Solution LD5513/LD5515) Output Voltage Type A: 5V, 9V, 12V Type B: 5V, 9V, 12V, 20V Pump Express (5V) Pump Express Plus (12V) Base on the D+/D‐ through USB Technology Base on Load Modulation through Vbus Charger needs to provide high output voltage and Charger needs to provide high output voltage and power to the cell phone power to the cell phone Quick Charge 2.0 Based Fast Charging The operation principle of Quick Charge 2.0: When the fast charging device receives the order dispatched from the devices (such as phone or tablet) that supports Quick Charge 2.0, it will adjust the ACDC output voltage of the charger to let the battery of the devise to receive a better input power. In order to meet the needs of the fast charging system, fast charging devices needs an additional charging interface IC at the secondary side. This IC will communicate with the power device and adjust the output voltage. Generally the output voltage is 5V/9V/12V (optional)/ 20V (optional). The charging speed is 75% faster base on the Quick Charge 2.0 protocol Interface IC Flyback Structured Fast Charging (For Quick Charge 2.0) L + D4 BR1 AC Input interface IC - D1 N interface IC Rectifier D+ D- Q1 Q2 Control IC D3 D2 Feedback Primary DC Output： 5.3V/2A; 9V/1.67A;12V/1.25A Function Product PWM IC Secondary Package Type Ref. Qty. Primary rectifier General Rectifier 2A/1000V SMAF GS2MF BR1 4 Snubber Fast Rectifier 1A/1000V SMAW RS1MW D1 1 Vcc stabilization Zener 500mW/12V SOD-123 MMSZ5242A D2 1 Vcc rectifier Fast Rectifier 1A/200V SOD-123FL RS1002FL D3 1 MOSFET 12mA/600V SOT-23 BSS126 Q1 1 MOSFET 6A/700V TO-251 PJU6NA70 Q2 1 15A/100V DO-201AD SBT15100VSS D4 1 12A/100V TO-277 SVT12100V D4 1 Switching Output rectifier Schottky Rectifier Synchronous Rectification Structured Quick Charge (For Quick Charge 2.0) L + BR1 AC Input interface D1 N IC - - SR’s Parallel Diode D+ D- D4 SR MOSFET - Q2 Control IC Primary D3 interface IC Q1 D2 PWM IC DC Output :5V/1.5A ; 9V/1.5A ; 12V/1.12A Function Product Secondary Package Type Ref. Qty. Primary rectifier General Rectifier 2A/1000V SMAF GS2MF BR1 4 Snubber Fast Rectifier 1A/1000V SMAW RS1MW D1 1 Vcc stabilization Zener 500mW/12V SOD-123 MMSZ5242A D2 1 Vcc rectifier Fast Rectifier 1A/200V SOD-123FL RS1002FL D3 1 MOSFET 11.1A/100V SO-8 PJL9456 Q1 1 MOSFET 6A/700V TO-251 PJU6NA70 Q2 1 Schottky Rectifier 1A/100V SOD-123FL SS10100FL D4 1 Switching SR’s Parallel Diode From Original Charging go Fast Charging (For Quick Charge 2.0) The popularization of Quick Charge2.0 has effected the device utilization of the secondary rectification side in charger products. The voltage required for Schottky devices has shift to 100V, which originally needed 45V; the voltage requirement of SR MOSFET has become 100V which originally needed 60V. FlyBack Schottky Test Condition: Vac=264V Vout=12V Result: VR_MAX=69.7V SR MOSFET Test Condition: Vac=264V Vout=12V Result: PIV= 83.2V Pump ExpressTM based Fast Charging The operation principle of Pump ExpressTM: Dynamically adjust the output voltage of the charger base on the actual electricity of the battery, which optimizes the charging time. The original USB charger charges the devices under a fixed output voltage. When the charger is operating, it creates a large amount of thermal consumption due to the differential pressure between the charger and the battery, which extends the charging time. VBAT 4.2V VBAT IBAT IBAT Original Charging Method： Fast Charging Method： Low current at low electricity→constant current till the end→when VBAT=4.2V, the current decreases, and then enter the stage of trickle current As the battery voltage increases, the charging current increases gradually. When the battery voltage reaches 4.2V, the charging current reaches its maximum value, so by constantly increasing the current, the charging time can be shorten, and literally become fast charging. Flyback Structured Fast Charging (For Pump ExpressTM ) L BR1 Q2 N Control IC Q1 Rectifier - D2 D3 D4 PWM IC Secondary Primary Function Primary rectifier + D5 D1 Product Package Type Ref. Qty. Bridge 0.8A/1000V MBF MB10F-08 BR1 1 TVS 600W/120V SMB P6SMB120A D1 1 Fast Rectifier 1A/1000V SMAW RS1MW D2 1 Vcc stabilization Zener 500mW SOD-123 MMSZ5242A D3 1 vcc rectifier Fast Rectifier 1A/200V SOD-123FL RS1002FL D4 1 NPN Transistor 1.5A/800V TO-92 N/A Q1 1 MOSFET 12mA/600V SOT-23 BSS126 Q2 1 5A/45V SMBF SRM54AVF D5 1 5A/45V SMAF SXM54ALF D5 1 Snubber Switching Output rectifier Schottky Rectifier