RT9204GS datasheet(13/14 Pages) RICHTEK

13 / 14 page

RT9204/A

Preliminary

DS9204/A-08 March 2007

www.richtek.com

The power components and the PWM controller should

be placed firstly. Place the input capacitors, especially the

high-frequency ceramic decoupling capacitors, close to

the power switches. Place the output inductor and output

capacitors between the MOSFETs and the load. Also

locate the PWM controller near by MOSFETs.

A multi-layer printed circuit board is recommended. Figure

13. shows the connections of the critical components in

the converter. Note that the capacitors CIN and COUT

each of them represents numerous physical capacitors.

Use a dedicated grounding plane and use vias to ground

all critical components to this layer. Apply another solid

layer as a power plane and cut this plane into smaller

islands of common voltage levels. The power plane should

support the input power and output power nodes. Use

copper filled polygons on the top and bottom circuit layers

for the PHASE node, but it is not necessary to oversize

this particular island. Since the PHASE node is subjected

to very high dV/dt voltages, the stray capacitance formed

between these island and the surrounding circuitry will

tend to couple switching noise. Use the remaining printed

circuit layers for small signal routing. The PCB traces

between the PWM controller and the gate of MOSFET

and also the traces connecting source of MOSFETs

should be sized to carry 2A peak currents.

Figure 13

LOAD

VCC

GND

RT9204/A

UGATE

IQ1

OUT

IQ2

GND

RT9204GS Datasheet(PDF) 13 Page - Richtek Technology Corporation