RT7273
Typical Application Circuit
32, 33, 34
13
V
12
IN
12V
VINR
VIN1
BOOT1
LX1
C7
C33
C23
100nF
V
OUT1
1.2V/3A
10µF
22µF
L1
RT7273
C10
10µF
4.7µH
14, 15
18
VIN2
VIN3
C13
C3
22µF
C18
22µF
R9
C17
10µF
470pF
40.2k
7
FB1
38
19
R12
80.8k
C9
BOOT2
C24
100nF
L2
4.7µH
10µF
V
OUT2
28
29
C27
3.3µF
1.8V/2A
PVCC
VCC
C26
10µF
16, 17
LX2
R1
40.2k
C32
470pF
C16
22µF
C21
22µF
8
24
39
COMP1
FB2
R5
10
9
R15
32.4k
RLIM1
SS1
20k
C19
NC
BOOT3
C31
100nF
L3
4.7µH
C2
R1
51k
V
OUT3
11
C5
4.7nF
4.7nF
3.3V/2A
EN1
C4
4.7nF
36, 37
4
LX3
FB3
R20
40.2k
C15
470pF
C11
22µF
C22
22µF
23
COMP2
R17
20k
C28
21
22
20
RLIM2
SS2
C20
NC
R13
12.7k
V
R16
75k
CC
4.7nF
EN2
C25
4.7nF
C29
4.7nF
R18
100k
27
3
PGOOD
SYNC
PGOOD
Input Signal
COMP3
5
R3
20k
C1
1
2
RLIM3
SS3
C14
NC
25
LOWP
R4
82k
40
C6
4.7nF
6
4.7nF
EN3
ROSC
C3
4.7nF
R7
383k
GND
26, 30, 31, 35,
41 (Exposed Pad)
Table 1. Suggested Component Values for CH1 (VIN = 12V, fS = 500kHz)
VOUT (V)
R9 (k)
40.2
R12 (k)
80.8
32.4
12.7
7.6
C13 (pF)
470
R5 (k)
20
C2 (nF)
4.7
L1 (H)
4.7
C3 (F)
1.2
1.8
3.3
5
44
44
44
44
44
40.2
470
20
4.7
4.7
40.2
470
20
4.7
4.7
40.2
470
24
5.6
6.8
7
40.2
5.2
470
24
5.6
6.8
Note 5. The suggested component values can be applied to CH 2 and CH 3 as well.
Note 6. Above values are fully tested for stable operation. When making changes to output capacitors or switching frequency,
please follow the guidelines in the application section.
Copyright 2014 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS7273-04 October 2014
www.richtek.com
9
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