Datasheet

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
SLUS564C − JULY 2003 − REVISED OCTOBER 2008
17
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APPLICATION INFORMATION
D The output voltage sensing trace and the feedback components should be as short as possible and be
isolated from the power components and traces.
D The low pass filter for VIN should be placed close to the TPS51020 and be referenced to signal GND.
D The bootstrap capacitor C
BST
(connected from VBST to LL) should be placed close to the TPS51020.
D VREG5 requires at least 4.7-µF bypass capacitor which should be placed close to the TPS51020 and be
referenced to signal GND.
D The discharge (VO1_VDDQ, VO2) should better have a dedicated trace to the output capacitor. In case of
limiting the discharge current, series resistors should be added.
D Ideally, all of the area directly under the TPS51020 chip should also be signal GND.
1
2
3
4
30
29
28
27
VBST1
OUT1_U
LL1
OUT1_D
INV1
COMP1
SSTRT1
SKIP
TPS51020
5
6
7
8
26
25
24
23
OUTGND1
TRIP1
VIN
TRIP2
VO1_VDDQ
DDR
GND
REF_X
9
10
11
22
21
20
VREG5
REG5_IN
OUTGND2
ENBL1
ENBL2
VO2
12 19OUT2_DPGOOD
13
14
15
18
17
16
LL2
OUT2_U
VBST2
SSTRT2
COMP2
INV2
Cvinbp
Rvin
L01
L_FET1
Cin1
H_FET1
Co1
Rtrip1 Ctrip1
+
−
L02
L_FET2
Cin2
H_FET2
Co2
Rtrips Ctrip2
+
−
Cvreg5
Cin
+
−
CH1 Output Voltage (+)
CH1 Output Voltage (GND)
Input Voltage (+)
Input Voltage (GND)
CH2 Output Voltage (GND)
CH2 Output Voltage (+)
Power GND
Signal GND
C
BST1
C
BST2
Figure 4. PCB Trace Guideline