High-Accuracy Step-Down Controller
with Synchronous Rectifier for CPU Power
The MAX798 contains the following seven major circuit
blocks, which are shown in Figure 2.
PWM Controller Blocks:
•
Multi-Input PWM Comparator
•
Current-Sense Circuit
•
PWM Logic Block
•
Gate-Driver Outputs
BATTERY VOLTAGE
Bias Generator Blocks:
•
+5V Linear Regulator
•
Automatic Bootstrap Switchover Circuit
•
+2.505V Reference
MAX798
TO
CSL
V+
4.5V
+5V LINEAR
REGULATOR
SHDN
OUT
VL
+5V AT 5mA
BST
SKIP
PWM
LOGIC
DH
LX
MAIN
OUTPUT
DL
+2.505V
REF
PWM
COMPARATOR
REF
1.6V
GND
1X
PGND
+2.505V
AT 100µA
CSH
CSL
ON/OFF
FB
SHDN
SYNC
SS
MAX798
Figure 2. Functional Diagram
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