Datasheet LTC1772 (Analog Devices) - 4

LTC1772
U U U PIN FUNCTIONS ITH/RUN (Pin 1):
This pin performs two functions. It
VFB (Pin 3):
Receives the feedback voltage from an exter- serves as the error amplifier compensation point as well as nal resistive divider across the output. the run control input. The current comparator threshold
SENSE– (Pin 4):
The Negative Input to the Current Com- increases with this control voltage. Nominal voltage range parator. for this pin is 0.7V to 1.9V. Forcing this pin below 0.35V causes the device to be shut down. In shutdown all
VIN (Pin 5):
Supply Pin. Must be closely decoupled to GND functions are disabled and the PGATE pin is held high. Pin 2.
GND (Pin 2):
Ground Pin.
PGATE (Pin 6):
Gate Drive for the External P-Channel MOSFET. This pin swings from 0V to VIN.
U U W FUNCTIONAL DIAGRA
SENSE– VIN 5 4 + ICMP – VIN RS1 SLOPE SWITCHING PGATE R COMP LOGIC AND OSC Q 6 BLANKING S CIRCUIT – FREQ OVP FOLDBACK + BURST + 0.3V + CMP SHORT-CIRCUIT V DETECT REF 0.15V – + SLEEP 60mV – VIN EAMP VREF + 0.8V 0.5µA VFB + 1 ITH/RUN – 3 V V IN IN 0.3V – 0.35V + SHDN VOLTAGE VREF SHDN REFERENCE 0.8V CMP – UV GND 2 UNDERVOLTAGE LOCKOUT 1.2V 1772 FD 1772fb 4