ADP3801 datasheet(19/20 Pages) AD

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ADP3801/ADP3802

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REV. 0

Board Layout Suggestions

When laying out the printed circuit board, the following check-

list should be used to ensure proper operation of the ADP3801

and ADP3802. These items are also illustrated graphically in

the layout diagram on the evaluation board application note.

Check the following in your layout:

1) The IC ground must return to a) the power and b) the signal

grounds with as short of leads as possible. If a double layer

PCB board is used and a ground plane is available, connect

all grounded parts directly to the ground plane. The ground

returns to the anode of the Schottky diode and the minus

terminal of CIN should have as short of lead lengths as possible.

2) Connect the IC’s current sense pins (CS+ and CS–) to RCS

with as short of leads (<0.5 inch) as possible.

3) Route the CS+ and CS– traces together with minimum spac-

ing. The filter capacitors should be close to the IC.

4) Connect the positive side of CIN as close as possible to the

source of the P-channel MOSFET (or the emitter of the

PNP). This capacitor provides the ac current to the pass

transistor.

5) Connect the input decoupling capacitor (0.l

µF) close to the

VCC input of the IC. This capacitor carries the DRV peak

currents.

6) Connect the 0.1

µF LDO decoupling capacitor as close as

possible to the VL pin.

7) The RESET pin has an internal pull-up, and should be pulled

low with an external resistor. The RESET pin is high imped-

ance and should not be allowed to float.

ADP3801 Datasheet(PDF) 19 Page - Analog Devices