rt9246a Richtek Technology Corporation, rt9246a Datasheet - Page 15

• Manufacturer Part Number: rt9246a
• Description: Multi-phase Controller Core Power Supply
• Manufacturer: Richtek Technology Corporation

Layout Guide
Place the high-power switching components first, and separate them from sensitive nodes.
1. Most critical path:
2. Switching ripple current path:
3. MOSFET driver should be closed to MOSFET.
DS9246A-04 March 2007
The current sense circuit is the most sensitive part of the converter. The current sense resistors tied to ISP1,2,3 and
ICOMMON should be located not more than 0.5 inch from the IC and away from the noise switching nodes. The PCB
trace of sense nodes should be parallel and as short as possible. R&C filter of choke should place close to PWM and
the R & C connect directly to the pin of each output choke, use 10 mil differencial pair, and 20 mil gap to other phase
pair. Less via as possible.
a. Input capacitor to high side MOSFET.
b. Low side MOSFET to output capacitor.
c. The return path of input and output capacitor.
d. Separate the power and signal GND.
e. The switching nodes (the connection node of high/low side MOSFET and inductor) is the most noisy points.Keep
f . Reduce parasitic R, L by minimum length, enough copper thickness and avoiding of via.
them away from sensitive small-signal node.
R
IN
V
V
IN
C
IN
Figure 18. Power Stage Ripple Current Path
SW2
SW1
L2
L1
V
OUT
C
OUT
RT9246A
R
L
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