Datasheet

LTC3528B-2
6
3528b2fa
PIN FUNCTIONS
Load Step Response
(1.2V to 3.3V)
SHDN (Pin 1): Logic Controlled Shutdown Input. There is
an internal 4MΩ pull-down resistor on this pin.
• SHDN = High: Normal operation
• SHDN = Low: Shutdown, quiescent current < 1µA
FB (Pin 2): Feedback Input. Connect resistor divider tap
to this pin. The output voltage can be adjusted from 1.6V
to 5.25V by:
V
OUT
= 1.20V • 1+
R2
R1






PGOOD (Pin 3): Power Good Comparator Output. This
open-drain output is low when V
FB
< 10% from its regu-
lation voltage.
V
OUT
(Pin 4): Output Voltage Sense and Drain Connection
of the Internal Synchronous Rectifier. PCB trace length
from V
OUT
to the output filter capacitor (4.7µF minimum)
should be as short and wide as possible.
SW (Pin 5): Switch Pin. Connect inductor between SW
and V
IN
. Keep PCB trace lengths as short and wide as
possible to reduce EMI. If the inductor current falls to
zero, or SHDN is low, an internal anti-ringing switch is
connected from SW to V
IN
to minimize EMI.
PGND (Pin 6): Power Ground. Provide a short direct PCB
path between PGND and the (–) side of the input and
output capacitors.
SGND (Pin 7): Signal Ground. Provide a short direct PCB
path between SGND and the (–) side of the input and
output capacitors.
V
IN
(Pin 8): Battery Input Voltage. Connect a minimum of
1µF ceramic decoupling capacitor from this pin to ground.
GND (Exposed Pad Pin 9): The exposed pad must be
soldered to the PCB ground plane. It serves as another
ground connection and as a means of conducting heat
away from the die.
Load Step Response
(3.6V to 5V)
V
OUT
100mV/DIV
20µs/DIV
35282 G22
V
IN
= 3.6V
V
OUT
= 5V
C
OUT
= 10µF
L = 2.2µH
LOAD CURRENT = 100mA TO 550mA
LOAD
CURRENT
200mA/DIV
V
OUT
100mV/DIV
20µs/DIV
35282 G24
V
IN
= 1.2V
V
OUT
= 3.3V
C
OUT
= 10µF
L = 2.2µH
LOAD CURRENT = 20mA TO 170mA
LOAD
CURRENT
100mA/DIV
TYPICAL PERFORMANCE CHARACTERISTICS
(T
A
= 25°C unless otherwise noted)