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Analog Devices Inc. LT3748EMS#PBF
- Part No.:
- LT3748EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3748EMS#PBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:367
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Product details
Overview
LT3748EMS#PBF from Analog Devices is a 100V isolated flyback controller IC designed for primary-side regulation in high-reliability isolated DC/DC converters. It drives an external N-channel MOSFET, operates in boundary mode, supports 5–100V input, delivers up to 25W output (e.g., 12V/2A), and eliminates need for opto-isolators or third-winding feedback.
For engineers reviewing the LT3748EMS#PBF datasheet, LT3748EMS#PBF pinout, LT3748EMS#PBF application, or LT3748EMS#PBF equivalent, key selection considerations include primary-side voltage sensing capability, 7V INTVCC gate driver supply, programmable UVLO and soft-start, boundary-mode frequency behavior, and MSOP-16 (12-lead) high-voltage package suitability for telecom, automotive, and industrial isolated supplies.
Technical Context
The LT3748EMS#PBF implements current-mode boundary conduction control with flyback waveform sampling on the primary side to derive isolated output voltage information-enabling regulation without optocouplers or auxiliary windings. Its internal error amplifier compares a temperature-compensated reference derived from RFB/RREF resistor divider against a 1.223V bandgap.
It features a dedicated SENSE pin with 90–110mV current-limit threshold (VC = 2.2V), programmable EN/UVLO (1.223V rising threshold), 1.9A average gate drive capability, and integrated 7V INTVCC regulator with 0.7V dropout at 10mA. Operating frequency varies dynamically with load and transformer magnetizing inductance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 100V - supports wide-input telecom (36–72V), industrial, and automotive battery-supplied systems. |
| INTVCC Regulation | 7.0V ±0.2V - powers gate driver and internal circuitry; stable bias enables robust MOSFET switching up to ~25W. |
| EN/UVLO Threshold | 1.223V (rising), 3.6V (INTVCC UVLO falling) - enables precise input undervoltage lockout programming via resistor divider. |
| SENSE Current Limit | 90–110mV (VC = 2.2V) - sets peak primary current; determines maximum deliverable power with selected RSENSE. |
| GATE Drive Capability | 1.9A avg source/sink - drives medium-power N-MOSFETs (e.g., 100V/5A) with fast 16ns rise/fall times (3.3nF load). |
| Operating Mode | Boundary conduction mode - ensures zero-current switching on secondary side, improving load regulation and enabling smaller magnetics. |
| Package | 16-lead MSOP (4 leads removed) - high-voltage rated, thermally enhanced package with θJA = 90°C/W. |
Pinout & Package
LT3748EMS#PBF is housed in a high-voltage 16-lead MSOP package with four leads (2, 4, 13, 15) removed - resulting in a 12-terminal footprint optimized for creepage and isolation in flyback designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main input supply reference | Bypassed locally; supplies startup circuitry and serves as reference for RFB feedback network. |
| EN/UVLO (3) | Enable & input undervoltage detection | Resistor-divider input; 1.223V rising threshold enables programmable turn-on; 2.4µA hysteresis current sets UVLO window. |
| INTVCC (5) | Internal gate driver supply | Regulated 7V output; powers GATE driver and internal logic; can be tied to VIN if ≤20V and no third winding used. |
| GATE (6) | N-MOSFET gate driver output | Switches between INTVCC and GND; 1.9A avg drive supports fast switching of external power FETs. |
| SENSE (7) | Primary-side current sense input | Kelvin-connected to RSENSE source; monitors peak switch current; 90–110mV threshold sets current limit. |
| GND (8,9) | Power and signal ground | Dual ground pins reduce noise coupling; connect to low-impedance PCB ground plane near SENSE and RSENSE. |
| SS (10) | Soft-start timing node | Sources 5µA to external capacitor; start-up delayed until VSS reaches ~0.65V; prevents inrush current. |
| VC (11) | Error amplifier compensation | Connect series RC to ground for loop stability; 100pF parallel cap suppresses noise; sink/source currents ±45µA. |
| TC (12) | Temperature compensation current source | Sinks 0.55V/RTC current into RREF to cancel diode VF drift; enables <±1% output tempco over –40°C to 125°C. |
| RREF (14) | Reference resistor connection | Accepts 6.04kΩ (nominal); sets gain for RFB-derived feedback; 1.223V internal bandgap reference referenced here. |
| RFB (16) | Primary-side feedback input | Connected to MOSFET drain; samples flyback pulse amplitude; ratio RFB/RREF × 1.223V defines output voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates opto-isolator and third winding - reduces BOM cost, improves reliability, avoids opto aging/nonlinearity. |
| Boundary conduction mode | Enables zero-current switching on secondary side - improves load regulation, allows smaller transformer, avoids subharmonic oscillation. |
| Programmable temperature compensation | TC pin current offsets diode forward-voltage drift - achieves stable output across –40°C to 125°C without external sensors. |
| High-voltage MSOP package | 16-lead MSOP with 4 leads removed - provides >5mm creepage/clearance for reinforced isolation in 100V-input designs. |
| Integrated 7V INTVCC regulator | Self-contained gate driver supply - removes need for external bias winding or LDO; simplifies layout and improves startup robustness. |
Applications
| Isolated Telecom Supply | Automotive High-Voltage DC/DC |
|---|---|
|
Use Scenario: 36–72V input telecom power module delivering regulated 12V/2A output for base station subsystems. IC Role / Device Role / Timing Role: Primary-side flyback controller performing boundary-mode switching, voltage sensing via RFB, and gate drive for external 100V MOSFET. Use Value: Achieves 25W output with ±1% line/load regulation, no opto-isolator required, and AEC-Q100-compliant operation up to 125°C junction. |
Use Scenario: 12V battery-backed 48V rail converter in ADAS domain controller, powering isolated CAN/FlexRay interfaces. IC Role / Device Role / Timing Role: Isolated flyback controller regulating secondary-side 5V/1A output using primary-side feedback; handles cold-crank (4.5V) to load-dump (60V) transients. Use Value: Enables compact, high-temperature-stable design meeting automotive EMI and reliability requirements without auxiliary winding complexity. |
| Industrial Isolated Sensor Power | Military/Aerospace Auxiliary Supply |
|
Use Scenario: 24V industrial PLC I/O module requiring isolated 3.3V/500mA supply for analog front-end and ADC reference. IC Role / Device Role / Timing Role: Boundary-mode flyback controller driving discrete MOSFET; senses output via RFB during flyback period; uses TC pin for precision tempco compensation. Use Value: Delivers tight output regulation across –40°C to 85°C ambient with no secondary-side components - reducing failure points in harsh environments. |
Use Scenario: 28V aircraft power system supplying isolated 15V/1A for avionics interface circuits operating at extended temperature (–55°C to 125°C). IC Role / Device Role / Timing Role: High-reliability flyback controller in MP-grade variant (LT3748MPMS#PBF); performs primary-side regulation with radiation-tolerant design margins. Use Value: Supports MIL-STD-704/DO-160 compliance with minimal external parts, eliminating opto-isolator lifetime uncertainty in mission-critical systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28911DR | Fixed-frequency quasi-resonant controller; requires auxiliary winding for VDD; no primary-side sensing; lower max input (85V). | Designed for cost-sensitive consumer AC/DC adapters; lacks TC pin and precise boundary-mode control for high-accuracy isolated DC/DC. | Choose UCC28911DR only for non-precision, low-cost AC/DC where auxiliary winding is acceptable and input stays below 85V. |
| MAX17690ATP+T | Current-mode flyback controller with primary-side sensing; 65V max input; integrated 7.5V LDO; no TC pin or programmable UVLO. | Targeted at industrial DC/DC with tighter size constraints; limited high-temp support (–40°C to 125°C only); no AEC-Q100 grade. | Choose MAX17690ATP+T for space-constrained 24–48V systems needing simpler tempco handling but not automotive qualification. |
Compared with UCC28911DR and MAX17690ATP+T, the LT3748EMS#PBF uniquely combines 100V input rating, true primary-side sensing without auxiliary winding, programmable temperature compensation, and AEC-Q100 qualification - making it the only option for high-accuracy, high-reliability isolated DC/DC in telecom, automotive, and military applications demanding full primary-side regulation.
Availability
LT3748EMS#PBF is available at Aetrix Electronics and suitable for isolated telecom converters, automotive high-voltage DC/DC modules, and industrial sensor power supplies requiring stable component supply, long-term lifecycle support, and guaranteed AEC-Q100 compliance.
Supply support for LT3748EMS#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices (now part of Analog Devices, Inc., following merger with Maxim Integrated) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, automotive, and communications markets.
The LT3748EMS#PBF belongs to Analog Devices' high-voltage isolated controller product line, engineered specifically for primary-side regulated flyback topologies in applications where reliability, temperature stability, and elimination of optocouplers are critical design requirements.
FAQ
What is the maximum input voltage supported by the LT3748EMS#PBF?
The LT3748EMS#PBF supports an absolute maximum input voltage of 100V on the VIN pin, with guaranteed operation across 5V to 100V. This makes it suitable for 48V telecom systems, 24–60V industrial rails, and automotive load-dump conditions. The device's high-voltage MSOP package and internal circuitry are rated for continuous operation at these levels, provided thermal limits are observed.
Does the LT3748EMS#PBF require an opto-isolator or third winding for regulation?
No, the LT3748EMS#PBF does not require an opto-isolator or third winding. It achieves isolated output regulation by sampling the flyback voltage waveform directly at the MOSFET drain (RFB pin), deriving output voltage information from the primary side. This architecture eliminates opto aging, nonlinearity, and auxiliary winding losses - a core differentiator confirmed in the device's official description and typical application schematics.
How is output voltage set on the LT3748EMS#PBF?
The LT3748EMS#PBF sets output voltage using two external resistors: RFB connected to the MOSFET drain and RREF tied to ground. The ratio RFB/RREF multiplies the internal 1.223V bandgap reference to determine the reflected primary voltage; combined with transformer turns ratio and diode drop, this yields the final secondary output. Temperature compensation is added via the TC pin and RTC resistor to offset diode VF drift.
What package type and temperature grade does the LT3748EMS#PBF use?
The LT3748EMS#PBF uses a 16-lead plastic MSOP package with four leads (2, 4, 13, 15) removed - forming a 12-terminal high-voltage footprint. It is rated for operation from –40°C to +125°C junction temperature and is specified as the "E" grade (industrial), distinct from the "I", "H", and "MP" variants with extended temperature ranges.
Can the LT3748EMS#PBF drive high-side or synchronous rectifier MOSFETs?
No, the LT3748EMS#PBF is a low-side N-channel MOSFET gate driver only. Its GATE pin switches between INTVCC and GND, and it does not support high-side drive, synchronous rectification, or P-channel FET control. Secondary-side rectification must use diodes or a separate synchronous rectifier controller - a limitation explicitly defined in the device's functional description and pinout documentation.
LT3748EMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 5V ~ 100V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3748EMS#PBF FAQ
1.How can I place an order for LT3748EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3748EMS#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT3748EMS#PBF reliable?
The price and inventory of LT3748EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3748EMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3748EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3748EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3748EMS#PBF?
LT3748EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3748EMS#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT3748EMS#PBF?
For technical support, including LT3748EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3748EMS#PBF requirements.
6.How does Aetrix verify that LT3748EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3748EMS#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT3748EMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3748EMS#PBF?
All LT3748EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3748EMS#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT3748EMS#PBF part is unused and in its original packaging.
Return procedure for LT3748EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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