Datasheet

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SLVS456C − OCTOBER 2003 − REVISED OCTOBER 2004
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19
SNUBBER CIRCUIT
R4 and C11 of the application schematic in Figure 24
comprise a snubber circuit. The snubber is included to
reduce over-shoot and ringing on the phase node when the
internal high-side FET turns on. Since the frequency and
amplitude of the ringing depends to a large degree on
parasitic effects, it is best to choose these component
values based on actual measurements of any design
layout. See literature number SLUP100 for more detailed
information on snubber design.
1
VIN
VIN
UVLO
PWRGD
RT
SYNC
ENA
COMP
PWRPAD
17
VSENSE
AGND
PGND
VBIAS
LSG
PH
PH
BOOT
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
U1
TPS54350PWP
C9
10
µF
C3
0.1
µF
C4
R4
4.7
Ω
C11
3300 pF
1
L1
10 µH
+
C2
100 µF
C6
82 nF
R3
768
Ω
C7
1800 pF
R2
374
Ω
R5
137
Ω
R1
1 k
Ω
C8
33 nF
6 V − 18 V
VOUT 3.3 V @ 3 A
D1
1 µF
2
D1: On Semiconductor MBRS340T3
L1: Vishay IHLP-5050CE
C2: Sanyo 6TPC100M
C1
47
µF
Figure 25. 3.3-V Power Supply With Schottky Diode
Figure 25 shows an application where a clamp diode is
used in place of the low-side FET. The TPS54350
incorporates an integrated pull-down FET so that the
circuit remains operating in continuous mode during light
load operation. A 3-A, 40-V Schottky diode such as the
Motorola MBRS340T3 or equivalent is recommended.