Datasheet

LTC3526L/LTC3526LB
6
3526lfc
SW (Pin 1): 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.
GND (Pin 2, Exposed Pad Pin 7): Si
gnal and Power Ground.
Provide a short direct PCB path between GND and the
(–) side of the input and output capacitors.
The Exposed
Pad must be soldered to the PCB ground plane. It serves
as an additional ground connection and as a means of
conducting heat away from the package.
V
IN
(Pin 3): Input Supply Pin. Connect a minimum of 1µF
ceramic decoupling capacitor from this pin to ground
using short direct PCB traces.
SHDN (Pin 4): Logic Controlled
Shutdown Input. There
is an internal 4MΩ pull-down
on this pin.
• SHDN =
High: Normal operation
• SHDN =
Low: Shutdown, quiescent current < 1µA
FB (Pin 5): Feedback Input
to the g
m
Error Amplifier. Con-
nect resistor divider tap to this pin. The top of the divider
connects to the output capacitor, the bottom of the divider
connects to GND. Referring to the Block Diagram, the output
voltage can be adjusted from 1.5V to 5.25V by:
V V
R
R
OUT
= +






1 195 1
2
1
. •
V
OUT
(Pin 6): Output voltage sense and drain of the internal
synchronous rectifier. PCB trace from V
OUT
to the output
filter capacitor (4.7µF minimum) should be as short and
Load Step Response (from Burst
Mode Operation) (LTC3526L)
Load Step Response
(Fixed Frequency)
LOAD
CURRENT
50mA/DIV
100µs/DIVV
IN
= 1.2V
V
OUT
= 3.3V
50mA TO 100mA STEP
C
OUT
= 10µF
3526l G21
V
OUT
100mV/DIV
AC-COUPLED
LOAD
CURRENT
50mA/DIV
50µs/DIVV
IN
= 1.2V
V
OUT
= 3.3V
5mA TO 100mA STEP
C
OUT
= 10µF
3526l G22
V
OUT
100mV/DIV
AC-COUPLED
typicAl perForMAnce chArActeristics
pin Functions