Rainbow Electronics MAX1637 - Manual (Page 9)

MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
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The pulse-width-modulation (PWM) controller consists
of a multi-input PWM comparator, high-side and low-
side gate drivers, and logic. It uses a 200kHz/300kHz
synchronizable oscillator. The MAX1637 contains fault-
protection circuits that monitor the PWM output for
undervoltage and overvoltage. It includes a 1.100V pre- cision reference. The circuit blocks are powered from
an internal IC power rail that receives power from V
CC .
V GG provides direct power to the synchronous-switch
gate driver, but provides indirect power to the high-
side-switch gate driver via an external diode-capacitor
boost circuit.
REF
IC
POWER
200kHz
TO
300kHz
OSC
PWM
LOGIC
3.15V TO 5.5V
V BATT
V OUT
REF
SHDN
SYNC V CC
DL
PGND
LX
DH
BST
V
GG
SKIP
CSH
CSL
FB
CC
REF
GND
V REF +7%
V
REF
-30%
+
60kHz
LP FILTER
SHUTDOWN
CONTROL
1.1V
REF.
ERROR
INTEGRATOR
+
-
+
-
+
-
+
-
+
MAX1637
gm
OVERVOLTAGE
FAULT
UNDER-
VOLTAGE
FAULT
OFF
SLOPE
COMPENSATION
V BIAS
Figure 2. Functional Diagram