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Analog Devices Inc. LT3748HMS#TRPBF
- Part No.:
- LT3748HMS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3748HMS#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:8,025
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Product details
Overview
LT3748HMS#TRPBF from Analog Devices is a high-voltage isolated flyback controller IC designed for primary-side regulation in telecom, automotive, and industrial power supplies. It operates from 5V to 100V input, delivers up to ~25W output (e.g., 12V/2A), uses boundary mode control, and eliminates opto-isolators or third windings by sensing output voltage directly from the primary-side flyback waveform.
For engineers reviewing the LT3748HMS#TRPBF datasheet, LT3748HMS#TRPBF pinout, LT3748HMS#TRPBF application, or LT3748HMS#TRPBF equivalent, this page provides verified technical context, exact pin functions, real-world load regulation behavior, thermal-grade packaging details (–40°C to 150°C), and validated alternative options for isolated flyback designs requiring AEC-Q100-compliant operation.
Technical Context
The LT3748HMS#TRPBF implements boundary-mode (critical conduction mode) current-mode control with primary-side sensing-sampling the MOSFET drain flyback pulse at zero secondary current to derive output voltage without optocouplers or auxiliary windings. Its internal error amplifier references a 1.223V bandgap and uses RFB/RREF resistor ratio plus transformer turns ratio to set VOUT.
It features programmable undervoltage lockout (1.223V threshold), 7V internally regulated INTVCC gate driver supply, 1.9A average gate drive capability, and temperature-compensated feedback via TC/RREF to offset diode forward-voltage drift. The H-grade variant guarantees full operation from –40°C to 150°C junction temperature.
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 without external pre-regulation. |
| Operating Junction Temp | –40°C to 150°C - qualified for under-hood automotive and high-temperature industrial environments; no derating required up to 150°C TJ. |
| INTVCC Regulation | 7.0V ±0.2V - powers internal gate driver; enables direct connection to VIN if ≤20V, eliminating need for external bias winding. |
| Gate Drive Capability | 1.9A avg source/sink - drives low-side N-channel MOSFETs with fast rise/fall times (16ns @ 3.3nF), supporting multi-watt isolated outputs. |
| SENSE Threshold Range | 15mV to 110mV - sets current limit via external sense resistor; minimum 15mV threshold allows precise low-current limiting. |
| Soft-Start Current | 5µA - charges external capacitor to delay startup; enables controlled inrush management in high-power flyback converters. |
| EN/UVLO Threshold | 1.223V rising - programmable input enable via resistor divider; 2.4µA hysteresis current ensures stable turn-on/turn-off transitions. |
Pinout & Package
LT3748HMS#TRPBF is housed in a 16-lead MSOP package with four leads removed (12-pin functional layout), rated for 150°C max junction temperature and θJA = 90°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main input supply reference | Bypassed locally; supplies start-up circuitry and serves as reference for RFB feedback network. |
| EN/UVLO (3) | Enable & input UVLO input | Resistor-divider programmed; sinks 2.4µA hysteresis current below threshold for clean shutdown. |
| INTVCC (5) | Internal gate driver bias rail | Regulated 7V output; can be tied to VIN if ≤20V, removing need for auxiliary winding or LDO. |
| GATE (6) | N-MOSFET gate driver output | Switches between INTVCC and GND; 1.9A avg drive supports fast switching of high-side referenced MOSFETs. |
| SENSE (7) | Primary-side current sense input | Kelvin-connected to MOSFET source resistor; detects peak current for cycle-by-cycle limiting (15–110mV range). |
| GND (8,9) | Power and signal ground | Dual ground pins reduce noise coupling; must be connected to low-impedance PCB plane near SENSE and GATE paths. |
| SS (10) | Soft-start timing node | Sources 5µA to external capacitor; startup delayed until SS reaches ~0.65V, preventing output overshoot. |
| VC (11) | Error amplifier compensation node | Connect RC network to ground for loop stability; 100pF parallel cap suppresses noise on compensation path. |
| TC (12) | Temperature compensation current source | Sinks current proportional to absolute temperature into RREF to cancel diode VF drift over temperature. |
| RREF (14) | Reference resistor connection | Accepts 6.04kΩ (±1%) resistor; sets gain for flyback-sampled feedback; bias current <500nA minimizes error. |
| RFB (16) | Feedback resistor connection | Connected to MOSFET drain; converts flyback pulse amplitude to current; ~200µA average current during flyback period. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates opto-isolator and third winding-reduces BOM count, improves reliability, and avoids aging/nonlinearity issues of optocouplers. |
| Boundary mode operation | Enables small magnetics with tight load regulation; prevents subharmonic oscillation and allows zero-current switching at light loads. |
| 150°C junction-rated package | Validated for automotive under-hood use per AEC-Q100; no external thermal derating needed up to 150°C TJ. |
| Programmable temperature compensation | TC pin sources PTAT current into RREF to offset diode forward-voltage drift-enables ±1% output regulation over full temp range. |
| Integrated 7V INTVCC regulator | Powers gate driver internally; supports direct VIN tie when ≤20V-removes need for auxiliary bias winding or external LDO. |
Applications
| Telecom Isolated Supply | Automotive High-Voltage DC/DC |
|---|---|
|
Use Scenario: 36–72V telecom rectified input powering isolated 12V/2A load in central office equipment. IC Role / Device Role / Timing Role: Primary-side flyback controller performing boundary-mode switching, output voltage sensing, and gate drive for external N-MOSFET. Use Value: Achieves 25W isolation without optocoupler or third winding-reducing component count, cost, and long-term drift vs. traditional solutions. |
Use Scenario: 12V–48V battery input powering isolated 5V/3A ECU subsystem in commercial vehicle under-hood environment. IC Role / Device Role / Timing Role: High-temp flyback controller regulating output via primary-side sampling while operating continuously at 150°C junction temperature. Use Value: AEC-Q100 qualification and 150°C rating enable direct placement near engine bay heat sources-eliminating remote mounting and thermal interface losses. |
| Industrial Isolated Power | Military/Harsh-Environment Supply |
|
Use Scenario: 24–100V industrial bus powering isolated 15V/1.5A sensor interface with strict EMI and reliability requirements. IC Role / Device Role / Timing Role: Boundary-mode controller delivering stable output across wide input range using only two external resistors for VOUT programming. Use Value: No opto-isolator simplifies certification (IEC 62368-1), improves MTBF, and avoids performance degradation due to LED aging or CTR variation. |
Use Scenario: 28V aircraft bus supplying isolated 28V/1A avionics module operating in extended temperature (-55°C to +125°C ambient). IC Role / Device Role / Timing Role: High-reliability flyback controller with MP-grade variants available; H-grade supports full spec operation up to 150°C junction. Use Value: Guaranteed parametric performance across –40°C to 150°C enables single-design reuse across military, aerospace, and oilfield applications. |
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 DCM controller; no boundary-mode sampling; requires optocoupler or auxiliary winding for regulation. | Limited to lower-power (<10W) applications; lacks primary-side sensing and temperature compensation. | Choose UCC28911DR only if fixed frequency is mandatory and optocoupler-based feedback is acceptable. |
| MAX17690ATP+T | 75V max input; no integrated INTVCC regulator; requires external 7V bias; no TC pin for diode compensation. | Not rated for >125°C operation; unsuitable for automotive under-hood or high-temp industrial use. | Select MAX17690ATP+T for cost-sensitive, non-automotive designs where input ≤75V and temperature ≤125°C. |
Compared with UCC28911DR and MAX17690ATP+T, the LT3748HMS#TRPBF uniquely combines 100V input support, primary-side regulation, 150°C operation, and integrated temperature compensation-making it the only option among the three qualified for AEC-Q100 automotive flyback supplies requiring no optocoupler and minimal external components.
Availability
LT3748HMS#TRPBF is available at Aetrix Electronics and suitable for telecom isolated converters, automotive high-voltage DC/DC modules, and industrial power supplies requiring stable component supply, long lifecycle support, and guaranteed high-temperature performance.
Supply support for LT3748HMS#TRPBF 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT3748HMS#TRPBF belongs to Analog Devices' isolated power controller product line, engineered specifically for primary-side regulated flyback topologies in harsh-environment applications demanding reliability, wide input range, and AEC-Q100 compliance.
FAQ
What is the maximum input voltage supported by the LT3748HMS#TRPBF?
The LT3748HMS#TRPBF supports an absolute maximum input voltage of 100V on the VIN pin, with guaranteed operation across the full 5V to 100V range. This makes the LT3748HMS#TRPBF suitable for telecom rectified inputs (36–72V), 48V industrial buses, and 24–48V automotive systems with transients. Exceeding 100V risks permanent damage per Absolute Maximum Ratings.
Does the LT3748HMS#TRPBF require an optocoupler or third winding for regulation?
No-the LT3748HMS#TRPBF performs primary-side regulation by sampling the MOSFET drain flyback pulse at zero secondary current, eliminating the need for optocouplers or auxiliary windings. This is confirmed in the device description, typical application schematic, and block diagram. The LT3748HMS#TRPBF achieves tight output regulation using only RFB and RREF resistors, reducing component count and improving long-term reliability.
What is the operating temperature grade of the LT3748HMS#TRPBF?
The LT3748HMS#TRPBF is the H-grade variant, specified for continuous operation from –40°C to 150°C junction temperature. This is explicitly stated in the ORDER INFORMATION table and Absolute Maximum Ratings section. Unlike the E/I-grade versions, the LT3748HMS#TRPBF is AEC-Q100 qualified and guaranteed over the full –40°C to 150°C range without derating.
How does the TC pin function in the LT3748HMS#TRPBF?
The TC pin on the LT3748HMS#TRPBF sources a current proportional to absolute temperature (PTAT) into the RREF node via an external resistor (RTC). This compensates for the negative temperature coefficient of the output diode's forward voltage drop (VF), enabling stable output regulation across temperature. The relationship is defined as ITC = 0.55V / RTC, and the LT3748HMS#TRPBF datasheet provides design equations to select RTC based on measured ΔVOUT/ΔT.
Can the LT3748HMS#TRPBF drive high-side or low-side MOSFETs?
The LT3748HMS#TRPBF drives only low-side N-channel MOSFETs via its GATE pin, which swings between INTVCC and GND. It does not support high-side drive or P-channel configurations. The datasheet explicitly states "drives a low side external N-channel power MOSFET" and shows all typical applications with low-side switch placement. Attempting high-side drive would violate the GATE output voltage specification and disable proper boundary-mode detection.
LT3748HMS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Packaging:
- Tape & Reel (TR)
- 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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3748HMS#TRPBF FAQ
1.How can I place an order for LT3748HMS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3748HMS#TRPBF 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 LT3748HMS#TRPBF reliable?
The price and inventory of LT3748HMS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3748HMS#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3748HMS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3748HMS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3748HMS#TRPBF?
LT3748HMS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3748HMS#TRPBF 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 LT3748HMS#TRPBF?
For technical support, including LT3748HMS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3748HMS#TRPBF requirements.
6.How does Aetrix verify that LT3748HMS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3748HMS#TRPBF 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 LT3748HMS#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3748HMS#TRPBF?
All LT3748HMS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3748HMS#TRPBF, 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 LT3748HMS#TRPBF part is unused and in its original packaging.
Return procedure for LT3748HMS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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