DocumentationDatasheet
Reliability Data
Product Selector Card
LT Journal
- Increase Current Capability and Simplify Thermal Design of Flyback Converters with Secondary-Side Synchronous Rectifier Driver in a 5-Pin SOT-23
- Isolated Power Supplies Made Easy
Press Release
- 100V Flyback Controller Now Offered in Military -55°C to 150°C MP Grade
- 100V Isolated Flyback DC/DC Controller Operates up to 150°C
- 100V Isolated Flyback DC/DC Controller Simplifies Design & Eliminates Optocoupler
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- LT3748 Demo Circuit - 100V No Opto Isolated Flyback Controller (48V to 12V @ 2A)
- LT3748 Demo Circuit - Automotive Isolated Flyback Controller (6-45V to 5V @ 2A)
- LT8309/LT3748 Demo Circuit - 40W, 5V Isolated Telecom Supply (36-72V to 5V @ 8A)
- LT8309/LT3748 Demo Circuit - 60W, 12V Output, Isolated Telecom Supply (36-72V to 12V @ 5A)
Features
- 5V to 100V Input Voltage Range
- 1.9A Average Gate Drive Source and Sink Current
- Boundary Mode Operation
- No Transformer Third Winding or Opto-Isolator Required for Regulation
- Primary-Side Winding Feedback Load Regulation
- VOUT Set with Two External Resistors
- INTVCC Pin for Control of Gate Driver Voltage
- Programmable Soft Start
- Programmable Undervoltage Lockout
- Available in MSOP Package
Typical Application
Description
The LT3748 is a switching regulator controller specifically designed for the isolated flyback topology and capable of high power. It drives a low side external N-channel power MOSFET from an internally regulated 7V supply. No third winding or opto-isolator is required for regulation as the part senses the isolated output voltage directly from the primary-side flyback waveform.
The LT3748 utilizes boundary mode to provide a small magnetic solution without compromising load regulation. Operating frequency is set by load current and transformer magnetizing inductance. The gate drive of the LT3748 combined with a suitable external MOSFET allow it to deliver load power up to several tens of watts from input voltages as high as 100V.
The LT3748 is available in a high voltage 16-lead MSOP package with four leads removed.
MS-16
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LT3748EMS#PBF | MSOP | 16 | E | $4.46 | $3.12 |
| LT3748EMS#TRPBF | MSOP | 16 | E | $3.18 | |
| LT3748HMS#PBF | MSOP | 16 | H | $5.66 | $3.71 |
| LT3748HMS#TRPBF | MSOP | 16 | H | $3.77 | |
| LT3748IMS#PBF | MSOP | 16 | I | $4.93 | $3.45 |
| LT3748IMS#TRPBF | MSOP | 16 | I | $3.51 | |
| LT3748MPMS#TRPBF | MSOP | 16 | MP | $9.31 | |
| LT3748MPMS#PBF | MSOP | 16 | MP | $13.22 | $9.25 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.
| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC1557A | LT3748EMS Isolated Demo Board | 30V Vin 75V; Vout = 12V @ 1A | $175.00 | |
| DC1694B | LT3748EMS Isolated Demo Board | No-Opto Flyback, 22V ≤ VIN ≤ 75V; VOUT = 12V @ 2.5A | $175.00 | |
| DC1860B | LT3748EMS Isolated Demo Board | 10V ≤ Vin ≤ 15V; Vout = 52.5V @ 0.7A | $175.00 | |
| DC1961A | LT8309ES5/LT3748EMS Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A | $175.00 |