Step-Down Controllers with
Synchronous Rectifier for CPU Power
CSH
CSL
1X
REF
FROM
FEEDBACK
DIVIDER
MAIN PWM
COMPARATOR
BST
DH
LX
R
Q
LEVEL
SHIFT
S
SLOPE COMP
OSC
30mV
SKIP
(MAX797
ONLY)
VL
4μA
CURRENT
LIMIT
SHOOT-
THROUGH
CONTROL
24R
1R
SS
2.5V
N
SHDN
SYNCHRONOUS
RECTIFIER CONTROL
VL
DL
R
Q
LEVEL
SHIFT
–100mV
S
PGND
REF (MAX796)
GND (MAX799)
1μs
NOTE 1: COMPARATOR INPUT POLARITIES
ARE REVERSED FOR THE MAX799.
SINGLE-SHOT
SECFB
NOTE 1
MAX796, MAX799 ONLY
Figure 3. PWM Controller Detailed Block Diagram
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