Datasheet LTC1772B (Analog Devices) - 5
| Manufacturer | Analog Devices |
| Description | Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23 |
| Pages / Page | 16 / 5 — PIN FUNCTIONS. ITH/RUN (Pin 1):. SENSE– (Pin 4):. IN (Pin 5):. PGATE (Pin … |
| File Format / Size | PDF / 226 Kb |
| Document Language | English |
PIN FUNCTIONS. ITH/RUN (Pin 1):. SENSE– (Pin 4):. IN (Pin 5):. PGATE (Pin 6):. GND (Pin 2):. VFB (Pin 3):. FUNCTIONAL DIAGRAM
Model Line for this Datasheet
Text Version of Document
LTC1772B
PIN FUNCTIONS ITH/RUN (Pin 1):
This pin performs two functions. It
SENSE– (Pin 4):
The Negative Input to the Current Com- serves as the error amplifi er compensation point as well parator. as the run control input. Nominal voltage range for this
V
pin is 0.85V to 1.9V. Forcing this pin below 0.35V causes
IN (Pin 5):
Supply Pin. Must be closely decoupled to GND Pin 2. the device to be shut down. In shutdown all functions are disabled and the PGATE pin is held high.
PGATE (Pin 6):
Gate Drive for the External P-channel MOSFET. This pin swings from 0V to V
GND (Pin 2):
Ground Pin. IN.
VFB (Pin 3):
Receives the feedback voltage from an external resistive divider across the output.
FUNCTIONAL DIAGRAM
SENSE– VIN 5 4 + 15mV ICMP – VIN RS1 SLOPE SWITCHING PGATE R COMP LOGIC AND OSC Q 6 BLANKING S CIRCUIT – FREQ OVP FOLDBACK + + 0.3V SHORT-CIRCUIT V DETECT REF + – 60mV EAMP VREF + 0.8V 0.5μA VFB + 1 ITH/RUN – 3 V V IN IN – 0.35V + SHDN VOLTAGE VREF SHDN REFERENCE 0.8V CMP – UV GND 2 UNDERVOLTAGE LOCKOUT 1.2V 1772FD 1772bfa 5
PIN FUNCTIONS ITH/RUN (Pin 1):
This pin performs two functions. It
SENSE– (Pin 4):
The Negative Input to the Current Com- serves as the error amplifi er compensation point as well parator. as the run control input. Nominal voltage range for this
V
pin is 0.85V to 1.9V. Forcing this pin below 0.35V causes
IN (Pin 5):
Supply Pin. Must be closely decoupled to GND Pin 2. the device to be shut down. In shutdown all functions are disabled and the PGATE pin is held high.
PGATE (Pin 6):
Gate Drive for the External P-channel MOSFET. This pin swings from 0V to V
GND (Pin 2):
Ground Pin. IN.
VFB (Pin 3):
Receives the feedback voltage from an external resistive divider across the output.
FUNCTIONAL DIAGRAM
SENSE– VIN 5 4 + 15mV ICMP – VIN RS1 SLOPE SWITCHING PGATE R COMP LOGIC AND OSC Q 6 BLANKING S CIRCUIT – FREQ OVP FOLDBACK + + 0.3V SHORT-CIRCUIT V DETECT REF + – 60mV EAMP VREF + 0.8V 0.5μA VFB + 1 ITH/RUN – 3 V V IN IN – 0.35V + SHDN VOLTAGE VREF SHDN REFERENCE 0.8V CMP – UV GND 2 UNDERVOLTAGE LOCKOUT 1.2V 1772FD 1772bfa 5
