Step-Down Controllers with
Synchronous Rectifier for CPU Power
____________________________________________Application Circuits (continued)
INPUT
0.1μF
C1
2x 22μF
1N4148
4.7μF
V+
VL
BST
DH
Q1
SHDN
T1
0.1μF
10μH
LX
MAX797
+5V OUTPUT
AT 3A
Q2
DL
C2
220μF
100k
1%
D1
1N5819
PGND
SS
FB
0.01μF
CSH
100k
1%
1.91Ω, 1%
1N4148
SKIP
CSL
SYNC
REF
T1 = 1:70 5mm SURFACE-MOUNT TRANSFORMER
DALE LPE-3325-A087
GND
0.33μF
Q1, Q2 = MMSF5N03 OR Si9410DY
Figure 20. Buck Converter with Low-Loss SMT Current-Sense Transformer
N1 = N2 = MTD20N03HDL
L1 = COILCRAFT DO3316-332
C1
220μF
OS-CON
INPUT
4.75V
TO 5.5V
0.1μF
D1
4.7μF
V+
VL
BST
DH
L1
3.3μH
R1
12mΩ
N1
N2
C3
0.1μF
1.5V OUTPUT
AT 5A
LX
C2
2 x 220μF
OS-CON
D2
ON/OFF
C6
DL
SHDN
SS
1N5820
PGND
MAX797
CSH
CSL
0.01μF
R6
49.9k
FB
C7
330pF
R5
150k
R7
124k
SYNC
REF
R3
66.5k
1%
TO
VL
SKIP
GND
C5
0.33μF
R4
100k
1%
MAX495
REMOTE SENSE LINE
Figure 21. 1.5V GTL Bus Termination Supply
30 ______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
