ACE4702

2 Cell Li-ion Battery Charger IC

VER 1.1

13

PCB Layout Considerations

When laying out the printed circuit board, the following considerations should be taken to ensure proper

operation of the IC.

(1) To minimize radiation, the 2 diodes, pass transistor, inductor and the input bypass capacitor traces

should be kept as short as possible. The positive side of the input capacitor should be close to the

source of the P-channel MOSFET; it provides the AC current to the pass transistor. The connection

between the catch diode and the pass transistor should also be kept as short as possible.

(2) The compensation capacitor connected at the COM1, COM2 and COM3 pins should return to the

analog ground pin of the IC. This will prevent ground noise from disrupting the loop stability.

(3) Output capacitor ground connections need to feed into same copper that connects to the input

capacitor ground before tying back into system ground.

(4) Analog ground and power ground(or switching ground) should return to system ground separately.

(5) The ground pins also works as a heat sink, therefore use a generous amount of copper around the

ground pins. This is especially important for high VCC and/or high gate capacitance applications.

single pair on the same layer at any given time with smallest trace spacing possible.

(7) The CSP and BAT pins should be connected directly to the current sense resistor (Kelvin sensing) for

best charge current accuracy. See Figure 4 as an example.

Figure 4 Kelvin Sensing of Charge Current