Datasheet LT1737 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | High Power Isolated Flyback Controller |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTIO. Drives External Power MOSFET. Supply Voltage Range: … |
| File Format / Size | PDF / 386 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. Drives External Power MOSFET. Supply Voltage Range: 4.5V to 20V. Flyback Voltage Limited Only by
Model Line for this Datasheet
Text Version of Document
LT1737 High Power Isolated Flyback Controller
U FEATURES DESCRIPTIO
■
Drives External Power MOSFET
The LT®1737 is a monolithic switching regulator control- ■
Supply Voltage Range: 4.5V to 20V
ler specifically designed for the isolated flyback topology. ■
Flyback Voltage Limited Only by
It drives the gate of an external MOSFET and is generally
External Components
powered from a DC supply voltage. Output voltage feed- ■
Senses Output Voltage Directly from Primary Side
back information may be supplied by a variety of methods
Winding—No Optoisolator Required
including a third transformer winding, the primary wind- ■
Switching Frequency from 50kHz to 250kHz
ing or even direct DC feedback (see Applications Informa-
with External Capacitor
tion). Its gate drive capability, coupled with a suitable ■ Moderate Accuracy Regulation Without User Trims external MOSFET and other power path components, can ■ Regulation Maintained Well into Discontinuous Mode deliver load power up to tens of Watts. ■ External ISENSE Resistor The LT1737 has a number of features not found on other ■ Optional Load Compensation isolated flyback controller ICs. By utilizing current mode ■ Optional Undervoltage Lockout switching techniques, it provides excellent AC and DC line ■ Shutdown Feature Reduces IQ to 50µA Typ regulation. Its unique control circuitry can maintain regu- ■ Available in 16-Pin GN and SO Packages lation well into discontinuous mode in most applications.
U
Optional load compensation circuitry allows for improved
APPLICATIO S
load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too ■ Isolated Flyback Switching Regulators low. An optional external capacitor implements a soft- ■ Medical Instruments start function. ■ Instrumentation Power Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO 12V-18V to Isolated 15V Converter
R2 VIN 35.7k 1% + C1 T1 D1 22µF COILTRONICS D2 MBRS1100 CTX150-4 BAS16 Q1 VOUT = 15V 2N3906 • 240k + IOUT = 300mA C2 R4 150µH 150µH 33µF 7.5k • C3 33k 0.1µF UVLO VCC M1 FB GATE IRFL014 LT1737 V I C SENSE R3 OSCAP t ENDLY MINENAB R R SGND PGND R1 ON OCMP CMPC 3.01k 0.27Ω 1% NOTE: SEE APPLICATIONS 1nF 47pF 75k 150k 100k 4.7k 0.1µF INFORMATION FOR ADDITIONAL COMPONENT SPECIFICATIONS 1737 TA01 1737fa 1
U FEATURES DESCRIPTIO
■
Drives External Power MOSFET
The LT®1737 is a monolithic switching regulator control- ■
Supply Voltage Range: 4.5V to 20V
ler specifically designed for the isolated flyback topology. ■
Flyback Voltage Limited Only by
It drives the gate of an external MOSFET and is generally
External Components
powered from a DC supply voltage. Output voltage feed- ■
Senses Output Voltage Directly from Primary Side
back information may be supplied by a variety of methods
Winding—No Optoisolator Required
including a third transformer winding, the primary wind- ■
Switching Frequency from 50kHz to 250kHz
ing or even direct DC feedback (see Applications Informa-
with External Capacitor
tion). Its gate drive capability, coupled with a suitable ■ Moderate Accuracy Regulation Without User Trims external MOSFET and other power path components, can ■ Regulation Maintained Well into Discontinuous Mode deliver load power up to tens of Watts. ■ External ISENSE Resistor The LT1737 has a number of features not found on other ■ Optional Load Compensation isolated flyback controller ICs. By utilizing current mode ■ Optional Undervoltage Lockout switching techniques, it provides excellent AC and DC line ■ Shutdown Feature Reduces IQ to 50µA Typ regulation. Its unique control circuitry can maintain regu- ■ Available in 16-Pin GN and SO Packages lation well into discontinuous mode in most applications.
U
Optional load compensation circuitry allows for improved
APPLICATIO S
load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too ■ Isolated Flyback Switching Regulators low. An optional external capacitor implements a soft- ■ Medical Instruments start function. ■ Instrumentation Power Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO 12V-18V to Isolated 15V Converter
R2 VIN 35.7k 1% + C1 T1 D1 22µF COILTRONICS D2 MBRS1100 CTX150-4 BAS16 Q1 VOUT = 15V 2N3906 • 240k + IOUT = 300mA C2 R4 150µH 150µH 33µF 7.5k • C3 33k 0.1µF UVLO VCC M1 FB GATE IRFL014 LT1737 V I C SENSE R3 OSCAP t ENDLY MINENAB R R SGND PGND R1 ON OCMP CMPC 3.01k 0.27Ω 1% NOTE: SEE APPLICATIONS 1nF 47pF 75k 150k 100k 4.7k 0.1µF INFORMATION FOR ADDITIONAL COMPONENT SPECIFICATIONS 1737 TA01 1737fa 1
