RT9204AGS RICHTEK [Richtek Technology Corporation], RT9204AGS Datasheet - Page 13

• Manufacturer Part Number: RT9204AGS
• Description: Dual Regulators - Standard Buck PWM DC-DC and Linear Controller
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT9204/A
Preliminary
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.
IQ1
IL
V
OUT
5V
Q1
IQ2
LOAD
GND
VCC
GND
UGATE
RT9204/A
FB
Figure 13
DS9204/A-08 March 2007
www.richtek.com
13