Datasheet LT1938 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | 25V, 2.2A, 2.8MHz Step-Down Switching Regulator |
| Pages / Page | 24 / 7 — PIN FUNCTIONS. BD (Pin 1):. PG (Pin 6):. BOOST (Pin 2):. BIAS (Pin 7):. … |
| File Format / Size | PDF / 271 Kb |
| Document Language | English |
PIN FUNCTIONS. BD (Pin 1):. PG (Pin 6):. BOOST (Pin 2):. BIAS (Pin 7):. SW (Pin 3):. VIN (Pin 4):. FB (Pin 8):. RUN/SS (Pin 5):
Model Line for this Datasheet
Text Version of Document
LT1938
PIN FUNCTIONS BD (Pin 1):
This pin connects to the anode of the boost
PG (Pin 6):
The PG pin is the open collector output of an Schottky diode. internal comparator. PG remains low until the FB pin is
BOOST (Pin 2):
This pin is used to provide a drive within 10% of the final regulation voltage. PG output is voltage, higher than the input voltage, to the internal bipolar valid when VIN is above 3.5V and RUN/SS is high. NPN power switch.
BIAS (Pin 7):
The BIAS pin supplies the current to the
SW (Pin 3):
The SW pin is the output of the internal power LT1938’s internal regulator. Tie this pin to the lowest switch. Connect this pin to the inductor, catch diode and available voltage source above 3V (typically VOUT). This boost capacitor. architecture increases efficiency especially when the input voltage is much higher than the output.
VIN (Pin 4):
The VIN pin supplies current to the LT1938’s internal regulator and to the internal power switch. This
FB (Pin 8):
The LT1938 regulates the FB pin to 1.265V. pin must be locally bypassed. Connect the feedback resistor divider tap to this pin.
RUN/SS (Pin 5):
The RUN/SS pin is used to put the
VC (Pin 9):
The VC pin is the output of the internal error LT1938 in shutdown mode. Tie to ground to shut down amplifier. The voltage on this pin controls the peak switch the LT1938. Tie to 2.3V or more for normal operation. If current. Tie an RC network from this pin to ground to the shutdown feature is not used, tie this pin to the V compensate the control loop. IN pin. RUN/SS also provides a soft-start function; see the
RT (Pin 10):
Oscillator Resistor Input. Connecting a resistor Applications Information section. to ground from this pin sets the switching frequency.
Exposed Pad (Pin 11):
Ground. The Exposed Pad must be soldered to the PCB. 1938fa 7 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL ChARACTERISTICS TYPICAL PERFORMANCE ChARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS
PIN FUNCTIONS BD (Pin 1):
This pin connects to the anode of the boost
PG (Pin 6):
The PG pin is the open collector output of an Schottky diode. internal comparator. PG remains low until the FB pin is
BOOST (Pin 2):
This pin is used to provide a drive within 10% of the final regulation voltage. PG output is voltage, higher than the input voltage, to the internal bipolar valid when VIN is above 3.5V and RUN/SS is high. NPN power switch.
BIAS (Pin 7):
The BIAS pin supplies the current to the
SW (Pin 3):
The SW pin is the output of the internal power LT1938’s internal regulator. Tie this pin to the lowest switch. Connect this pin to the inductor, catch diode and available voltage source above 3V (typically VOUT). This boost capacitor. architecture increases efficiency especially when the input voltage is much higher than the output.
VIN (Pin 4):
The VIN pin supplies current to the LT1938’s internal regulator and to the internal power switch. This
FB (Pin 8):
The LT1938 regulates the FB pin to 1.265V. pin must be locally bypassed. Connect the feedback resistor divider tap to this pin.
RUN/SS (Pin 5):
The RUN/SS pin is used to put the
VC (Pin 9):
The VC pin is the output of the internal error LT1938 in shutdown mode. Tie to ground to shut down amplifier. The voltage on this pin controls the peak switch the LT1938. Tie to 2.3V or more for normal operation. If current. Tie an RC network from this pin to ground to the shutdown feature is not used, tie this pin to the V compensate the control loop. IN pin. RUN/SS also provides a soft-start function; see the
RT (Pin 10):
Oscillator Resistor Input. Connecting a resistor Applications Information section. to ground from this pin sets the switching frequency.
Exposed Pad (Pin 11):
Ground. The Exposed Pad must be soldered to the PCB. 1938fa 7 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL ChARACTERISTICS TYPICAL PERFORMANCE ChARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS
