Compatible with PD and QC fast charger two series 8.4V lithium battery 1A charging board - PCB design scheme

The nominal voltage of the two stringsof lithium battery is 7.4V lithium battery pack, but the actual voltage is 6Vdischarge to 8.4V full charge, so the output power supply voltage is 6V-8.4V.Our usual management control for the two strings of lithium battery is to use5V pure boost mode, and the charger can output 5V. However, the voltage of thefast-charging device is 5V,9V,12,20V, etc., if it needs to be compatible withthe high-voltage input of the fast-charging device, such as the input of 5V and9V, it needs the voltage lifting charge management chip. At present, the costof the voltage lifting product is high. you canfirst use the following way to use, When the market feedback demand isstrong, we will start the planned voltage lifting product.

1 Circuit board PCB description：

1.1 Name ： Compatible with PD and QC fast charger twoseries 8.4V lithium battery 1A charging board

1.2 Battery pack: 7.4Vlithium battery pack, multiple parallel or two series connection, full 8.4V

1.3 Input voltage: 5V-12V Max charging current ： 1A（ Whencharging, the light will be on, and when it is fully charged, the light willturn）

1.4 Introduction to ChipFunctions ：

1， Lithium battery charging circuit：PW4202

PW4202 Lithium battery charge management chip， Up to 3.5A charging current， switching type high efficiency, support two series lithium battery charging.

2， DC-DC synchronous step-down circuit：PW2303

PW2303 Synchronous Buck Chip， Input 30V-5V, output5V, up to 3A, characterized by voltage step-down voltage difference is verylow, and high efficiency.

3， USB C port PD fast charge Protocol chip： PW6605

PW6605 is a PD/QC fast chargeprotocol chip, SINK terminal, responsible for protocol communication PD chargerto output its specified voltage

2， Circuit diagram ：

PCB layout is dividedinto two parts: signal controlcircuit + power circuit

Note 1： The blue thick line is the power trace, the layout should bewide； SW part (The connection point of L2,D1 and Q1 ofPW4202) is not only the power output, but also it is a noise source, the layoutshould be wide and the area should be small.

Note2： The red thick line is the power ground,the main points of the drawing board: to be wide, the shorter the distance between the connecting loops at each point, the more holes are punched in theground. (Input, C1, C2, PW2303 pin 7/8, C3, C7, C6, C8, C9, Q1 and the batteryground)

3， PCB diagram and 3Ddisplay diagram

4 ， BOM Material List

Comment	Designator	Footprint	Quantity
100uF 25V 6.3*7.7mm Electrolytic capacitance	C1	6.3*7.7mm	1
0603 25V 0.1uF	C2, C7	0603A	2
330uF 16V 8*10mm Electrolytic capacitance	C3	8*10mm	1
0603 50V 220pF	C4	0603A	1
0603 25V 1uF	C5	0603A	1
0805 25V 22UF	C6, C8, C9	0805C	3
SS34 SMB	D1	SMB	1
Plug-in ring type iron-silicon aluminum 47UH，Wire diameter above 0.7	L1	DIP	1
Integrated molded inductor 0650-6.8UH	L2	SMD	1
0603 LED Red	LED1	0603A	1
0603 LED Green	LED2	0603A	1
PW4406 PWCHIP MOS tube	Q1	SOP8	1
0603 1% 100K	R1	0603SL	1
0603 1% 24.9K	R2	0603SL	1
0603 5% 4.7R	R4	0603SL	1
0603 1% 10k	R5	0603SL	1
0603 5% 1k	R6	0603SL	1
1210 1% 60mR	R7	1206R	1
0603 1% 6.8K for input 9V，or 24K for input 12V	R8	0603SL	1
0603 5% 1k	R9, R10, R12	0603SL	3
0603 1% 0R	R11	0603SL	1
PW2303 PWCHIP Buck chips	U1	SOP8	1
PW4202 PWCHIP charge chips	U3	SOP8	1
PW6605 PWCHIP Fast Chips	U4	ESOP10	1
USB TYPE C 16PIN	USB1	USB	1