RT9218GS Richtek USA Inc, RT9218GS Datasheet - Page 15

• Manufacturer Part Number: RT9218GS
• Description: IC CTRLR PWM SYNC BUCK 14SOP
• Manufacturer: Richtek USA Inc

Specifications of RT9218GS

• Topology: Step-Down (Buck) Synchronous (1), Linear (LDO) (1)
• Function: Any Function
• Number Of Outputs: 2
• Frequency - Switching: 300kHz
• Voltage/current - Output 1: Controller
• Voltage/current - Output 2: Controller
• W/led Driver: No
• W/supervisor: No
• W/sequencer: No
• Voltage - Supply: 5V, 12V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RT9218
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
RT9218
UGATE
FB
Figure 10. The connections of the critical components in the converter
Below PCB gerber files are our test board for your reference :
DS9218-08 March 2007
www.richtek.com
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