M
S tep-Down Controllers with
S ync hronous Rec tifier for CPU Power
______________________________________________________________________________________
29
MAX797
CSL
CSH
VL
SYNC
REF
GND
TO
VL
V+
Q1
Q2
FB
1000pF
R1
63.4k
0.1%
R2
200k
0.1%
10k
OUTPUT
3.3V ±1.8%
REMOTE
SENSE
POINT
BST
DH
LX
DL
PGND
SKIP
SS
SHDN
INPUT
4.7
μ
F
0.33
μ
F
0.01
μ
F
R
SENSE
V
OUT
USE EXTERNAL REFERENCE
(MAX872) FOR BETTER ACCURACY.
ADJUST RANGE = 2.5V TO4V AS SHOWN.
OMIT R2 FOR V
OUT
= 2.5V.
= V
REF
(
1 + R1
)
R2
L1
MAX495
51k
5%
200k
5%
51k
5%
Figure 18. High-Accuracy Adjustable-Output Application
MAX797
CSL
CSH
VL
1N5819
SYNC
REF
GND
V+
Si9410
Si9410
FB
-5V AT 1.5A
BST
DH
LX
DL
PGND
SKIP
INPUT
4.5V TO25V
SHDN
0.33
μ
F
0.1
μ
F
4.7
μ
F
22
μ
F
22
μ
F
1N4148
L1
0.025
150
μ
F
150
μ
F
L1 = DALE LPE6562-A093
Figure 19. Negative-Output (Inverting Topology) Power Supply
____________________________________________Applic ation Circ uits (c ontinued)