Datasheet

LTC3532
6
3532fc
BLOCK DIAGRA
W
PI FU CTIO S
UUU
SHDN/SS (Pin 8): Combined Soft-Start and Shutdown.
Grounding this pin shuts down the IC. Tie to >1.5V to
enable the IC and >2.4V to ensure the error amp is not
clamped from soft-start. For Burst Mode operation, this pin
must be pulled up to within 0.5V of V
IN
. An RC from the
shutdown command signal to this pin will provide a soft-
start function by limiting the rise time of the V
C
pin.
FB (Pin 9): Feedback Pin. Connect resistor divider tap
here. The output voltage can be adjusted from 2.4V to
5.25V. The feedback reference is typically 1.22V. Set V
OUT
according to the formula:
V
OUT
=
1.22V • R1+ R2
()
R2
V
C
(Pin10): Error Amp Output: A frequency compensa-
tion network is connected from this pin to the FB pin to
compensate the loop. Refer to the Applications Information
section for component value selection.
Exposed Pad (Pin11): The exposed pad (DFN Package)
must be soldered to PCB ground for electrical contact and
rated thermal performance.
–
+
–
+
–
+
–
+
–
+
–
+
–
+
7
PWM
LOGIC
GATE
DRIVERS
AND
ANTICROSS
CONDUCTION
GND
UVLO
1.1A
2.3V
OSC
PEAK CURRENT
LIMIT
SW A
SW1
V
IN
V
CC
V
IN
V
IN
SW2
SW D
ERROR
AMP
1.22V
REVERSE
AMP
SW B SW C
5
3 4
V
OUT
6
FB
9
BURST
2
V
C
10
8
SHDN/SS
1
R
T
3532 BD
PWM COMP
THERMAL
SHUTDOWN
SHUTDOWN
SOFT-START
SHUTDOWN
1.22V
V
REF
AUTOMATIC
Burst Mode
CONTROL AND
V
C
HOLD
g
m
= 1/60k
1A
V
REF
SLEEP
SS