ADP3164 Просмотр технического описания (PDF) - Analog Devices

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ADP3164

5-Bit Programmable 4-Phase Synchronous Buck Controller

Analog Devices 

ADP3164

13. Whenever a power dissipating component (e.g., a power

MOSFET) is soldered to a PCB, the liberal use of vias,

both directly on the mounting pad and immediately sur-

rounding it, is recommended. Two important reasons for

this are: improved current rating through the vias, and

improved thermal performance from vias extended to the

opposite side of the PCB where a plane can more readily

transfer the heat to the air.

14. The output power path, though not as critical as the switch-

ing power path, should also be routed to encompass a small

area. The output power path is formed by the current path

through the inductor, the current sensing resistor, the out-

put capacitors, and back to the input capacitors.

15. For best EMI containment, the power ground plane should

extend fully under all the power components except the out-

put capacitors. These components are: the input capacitors,

the power MOSFETs and Schottky diodes, the inductors,

the current sense resistor, and any snubbing element that

might be added to dampen ringing. Avoid extending the

power ground under any other circuitry or signal lines,

including the voltage and current sense lines.

Signal Circuitry

16. The output voltage is sensed and regulated between the FB

pin and the GND pin (which connects to the signal ground

plane). The output current is sensed (as a voltage) by the

CS+ and CS– pins. In order to avoid differential mode

noise pickup in the sensed signal, the loop area should be

small. Thus the FB trace should be routed atop the signal

ground plane, and the CS+ and CS– pins (the CS+ pin

should be over the signal ground plane as well).

17. The CS+ and CS– traces should be Kelvin-connected to

the current sense resistor, so that the additional voltage

drop due to current flow on the PCB at the current sense

resistor connections, does not affect the sensed voltage.

–14–

REV. 0

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