LTC3428

5

3428fb

PIN FUNCTIONS

PGNDA, PGNDB (Pins 1, 10, 11 (Exposed Pad)): Power

Ground for the IC. Tie directly to local ground plane.

SWA (Pin 2), SWB (Pin 9): Phase B and Phase A Switch

Pins. The inductor and Schottky diodes for each phase

are connected to these pins. Minimize trace length to

reduce EMI.

Power Source for the IC. Connect low ESR output filter

capacitors from this pin to the ground plane.

SHDN (Pin 4): Shutdown Pin. Grounding this pin shuts

down the IC. Connect to a voltage greater than 1.5V to

enable.

network is connected to this pin to compensate the boost

converter loop.

connected here to set the output voltage according to

AGND (Pin 7): Signal Ground for the IC. Connect to ground

plane near feedback resistor divider.

ceramic capacitor of at least 4.7μF. X5R and X7R dielectrics

are preferred for their superior voltage and temperature

characteristics.

BLOCK DIAGRAM

–

+

–

+

–

PWM

COMP

+

–

–

PWM

COMP

PWM

LOGIC

PWM

LOGIC

TSD

CURRENT

LIMIT

CURRENT

LIMIT

1.243V

ERROR AMPLIFIER/SOFT-START

RAMP/

SLOPE COMP

OSCILLATOR

CLK B

CLK A

CHANNEL B

CHANNEL A

RAMP/

SLOPE COMP

FB

DRIVER

DRIVER

SWB

PGNDB

SWA

PGNDA

SHDN

SHUTDOWN

AGND

3428 BD

FB

5pF