rt9218b Richtek Technology Corporation, rt9218b Datasheet - Page 14

• Manufacturer Part Number: rt9218b
• Description: Synchronous Buck Dc-dc Linear Power Controller
• Manufacturer: Richtek Technology Corporation

RT9218B
Figure 10 shows the connections of the critical components in the converter. Note that the capacitors C
and C
each
IN
OUT
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
5V/12V
OUT
Q1
LOAD
IQ2
Q2
GND
VCC
GND
LGATE
RT9218B
UGATE
FB
Figure 10. The connections of the critical components in the converter
Below PCB gerber files are our test board for your reference :
www.richtek.com
DS9218B-09 March 2007
14