rt9245b Richtek Technology Corporation, rt9245b Datasheet - Page 21

• Manufacturer Part Number: rt9245b
• 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: the current sense circuit is the most sensitive part of the converter. The current sense
2. Switching ripple current path:
3. MOSFET driver should be closed to MOSFET.
4. The compensation, bypass and other function setting components should be near the IC and away from the noisy
DS9245B-02 March 2007
resistors tied to CSP1,2,3,4 and CSN 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.
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.
f. Reduce parasitic R, L by minimum length, enough copper thickness and avoiding of via.
power path.
Keep them away from sensitive small-signal node.
R
IN
V
V
IN
C
IN
Figure 32. Power Stage Ripple Current Path
SW1
SW2
L2
L1
V
OUT
C
OUT
RT9245B
R
L
www.richtek.com
21