Datasheet

MAX796/MAX797/MAX799
Step-Down Controllers with
Synchronous Rectifier for CPU Power
26 ______________________________________________________________________________________
MAX796
CSL
CSH
SECFB
GND REF
FB
SYNC
V+ VL
10 2 11
43 5
14
Q1
T1 = TDK 1:1.5 TRANSFORMER
PC40EEM 12.7/13.7 - A160 CORE
BEM 12.7/13.7 BOBBIN
PRIMARY = 8 TURNS 24 AWG
SECONDARY = 12 TURNS 24 AWG
DESIGN FOR TIGHT MAGNETIC COUPLING
Q1-Q2 = Si9410 or EQUIVALENT
Q3 = Si9955 or EQUIVALENT (50V)
Q2 Q3
16
15
13
1N4148
1N5819
MBR0502L
1N5817
12
8
9
7
V
IN
(8V TO 18V AS SHOWN)
+5V
AT
500mA
+3.3V
AT 2A
BST
DH
LX
DL
6
ON/OFF
1
PGND
SHDN
SS
0.33µF
4.7µF
47µF
330µF
0.1µF
33µF, 35V
10µH
25mΩ
T1
1:1.5
100k, 1%
102k
1%
49.9k
1%
33.2k
1%
102k, 1%
0.01µF
(OPTIONAL)
Figure 12. +3.3V/+5V Dual-Output Application (MAX796)
MAX799
CSL
CSH
VL
SS
GND
REF SECFB 10
3211
14
14
1/2
Si9936
1/2 Si9936
EQ11FS1
T1 = TRANSPOWER TTI5926
16
15
13
1N4148
1N5819
12
8
9
FB
7
V
IN
(9V TO 18V)
-5.5V OUT
(-5.5V AT 200mA)
+5V OUT
(+5V AT 1A)
BST
V+
DH
LX
DL
6
5
ON/OFF
PGND
SHDN
SYNC
0.01µF
(OPTIONAL)
220µF
10V
0.1µF
22µF, 35V
1µF
22µF
10V
50mΩ
T1
15µH
1:1.3
221k, 1%
1000pF
107k, 1%
4.7µF
Figure 13. ±5V Dual-Output Application (MAX799)
____________________________________________Application Circuits (continued)