LTC3521 LINER [Linear Technology], LTC3521 Datasheet - Page 8

• Manufacturer Part Number: LTC3521
• Description: Wide VIN, 1A Buck-Boost DC/DC and Dual 600mA Buck DC/DC Converters
• Manufacturer: LINER [Linear Technology]

LTC3521
pin FuncTions
NC (Pin 19, UF Package Only): No Internal Connection.
PV
tion Used to Supply the Buck Converter Power Switches.
This pin should be bypassed by a 10µF or larger ceramic
cap. The bypass capacitor should be placed as close to
the pin as possible and should have a short return path
to ground. Pins V
together in the application circuit.

block DiaGraM
IN2
(Pin 20/Pin 22): High Current Power Supply Connec-
IN
22
19
24
, PV
8
4
6
2
V
PWM
SHDN2
PV
SW2
FB2
PGOOD2
INTERNAL
IN
IN2
IN1
V
CC
11
, and PV
PGND2
PV
PV
0.60V
0A
IN2
SOFT-START
IN1
RAMP
A
1.05A
+
–
(UF Package)
–
+
+
g
–
+
m
PGND1A
IN2
DRIVES
GATE
ZERO CROSSING
15
+
–
0.55V
SW1A
B
must be connected
+
PGND1B
I
C
LIMIT
14
SW1B
SLOPE
COMPENSATION
OSCILLATOR
+
–
DRIVES
LOGIC
GATE
UVLO
BUCK
PWM
GND
5
D
0.55V
0.6V
0.9V
0.375A
1V
0A
PGND1A
21
BUCK-BOOST
REFERENCE
SHUTDOWN
BANDGAP
16
+
–
+
–
AND OT
PV
LOGIC
PWM
2.1A
OUT
PGND1B
Exposed Pad (Pin 21/Pin 25): The Exposed Pad must
be electrically connected to ground. Pins GND, PGND1A,
PGND1B, PGND2 and the Exposed Pad must be connected
together in the application circuit.
PGND1A (Pin 21, UF Package Only): High Current Ground
Connection for the Buck-Boost Switch B. The PCB trace
connecting this pin to ground should be made as short
and wide as possible.
REVERSE I
I
ZERO
12
+
–
FORWARD
I
LIMIT
LIMIT
SLOPE
COMPENSATION
LOGIC
BUCK
PWM
PGND2
18
0.55V
+
–
ZERO CROSSING
FILTER
I
LIMIT
+
–
–
+
+
+
0.55V
DRIVES
0.6V
GATE
+
–
g
m
–
+
1.05A
–
+
+
SOFT-START
RAMP
+
–
SOFT-START
PV
PGND2
0.60V
PV
RAMP
OUT
0A
IN2
PGOOD1
PGOOD3
SHDN1
SHDN3
SW3
FB1
FB3
3521 BD
23
10
17
3
9
7
1
3521f