LTC3700EMS View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC3700EMS

Constant Frequency Step-Down DC/DC Controller with LDO Regulator

Linear Technology 

LTC3700

PIN FUNCTIONS

VIN2 (Pin 1): LDO Input Supply Pin. Must be closely

decoupled to GND (Pin 5).

LDO (Pin 2): LDO Output Pin. Must be closely decoupled

to GND (Pin 5) with a low ESR ceramic capacitor ≥ 2.2µF.

VFB2 (Pin 3): LDO Feedback Voltage. Receives the feed-

back voltage from an external resistor divider between

LDO (Pin 2) and GND (Pin 5).

PGOOD (Pin 4): Open-Drain Power Good Output. This pin

will pull to ground if either voltage output of the buck or the

LDO [sensed at VFB (Pin 9) and VFB2 (Pin 3), respectively]

is out of range. When both voltage outputs are valid, this

pin will go to a high impedance state.

GND (Pin 5): Common Ground Pin for Both Buck and LDO.

PGATE (Pin 6): Gate Drive for Buck’s External P-Channel

MOSFET. This pin swings from 0V to VIN.

VIN (Pin 7): Buck Input Supply Pin. Must be closely

decoupled to GND (Pin 5).

SENSE– (Pin 8): The Negative Input to the Current Com-

parator of the Buck. Monitors switch current of external

P-Channel MOSFET.

VFB (Pin 9): Buck Feedback Voltage. Receives the feed-

back voltage from an external resistor divider between

buck output and GND (Pin 5).

ITH/RUN (Pin 10): This pin performs two functions. It

serves as the error amplifier compensation point for the

buck, as well as a common run control input for both the

buck and the LDO. The current comparator threshold of

the buck increases with this voltage. Nominal voltage

range for this pin is 0.7V to 1.9V. Forcing this pin below

0.3V causes both the buck and the LDO to be shut down.

In shutdown all functions are disabled, the PGATE pin is

held high and the LDO output will go to a high impedance

state.

3700f

6

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