W-6139 Datasheet, PDF (11/13 Pages) Copal Electronics – 22 V High Current Boost

W-6139
Board Layout
The W-6139 is a high-frequency switching regulator.
The traces that carry the high-frequency switching current
have to be carefully laid out on the board in order to
minimize EMI, ripple and noise in general. The thicker lines
on Figure 26 show the switching current path. All these
traces have to be short and wide enough to minimize the
parasitic inductance and resistance. The loop shown on
Figure 26 corresponds to the current path when the
W-6139 internal switch is closed. On Figure 27 is shown
the current loop, when the W-6139 switch is open. Both
loop areas should be as small as possible.
Capacitor C1 has to be placed as close as possible to the
VIN pin and GND. The capacitor C2 has to be connected
separately to the top LED anode. A ground plane under the
W-6139 allows for direct connection of the capacitors to
ground. The resistor R1 must be connected directly to the
GND pin of the W-6139 and not shared with the switching
current loops and any other components.
L
V_IN
D
V _OUT
L
V_IN
D
V_OUT
VIN
W-6139
SHDN
SW
Switch
Closed
FB
VIN
W-6139
SHDN
SW
Switch
Open
FB
C₁
GND
C₂
R1 C₁
GND
C₂
R1
Figure 26. Closedïswitch Current Loop
Figure 27. Openïswitch Current Loop
Figure 28. Recommended PCB Layout
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