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Analog Devices Inc. LT3748HMS#PBF
- Part No.:
- LT3748HMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3748HMS#PBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:871
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Product details
Overview
LT3748HMS#PBF 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 via direct primary-side flyback waveform sensing.
For engineers reviewing the LT3748HMS#PBF datasheet, LT3748HMS#PBF pinout, LT3748HMS#PBF application, or LT3748HMS#PBF equivalent, key selection considerations include its –40°C to 150°C junction temperature rating, 1.9A average gate drive capability, programmable soft-start and UVLO, INTVCC-regulated 7V gate driver supply, and MSOP-16 (12-lead) package with thermal enhancement.
Technical Context
The LT3748HMS#PBF implements boundary conduction mode (BCM) current-mode control to achieve tight load regulation without secondary-side feedback components. Its flyback error amplifier samples the drain voltage at zero-secondary-current crossing, using RFB/RREF resistor ratio and internal 1.223V bandgap reference to derive output voltage.
It integrates a 7V INTVCC regulator (4.5V–20V range, 7.0V typical), 1.9A average gate drive source/sink, programmable EN/UVLO threshold (1.223V rising), and temperature-compensated output regulation via TC pin current sourcing into RREF. The device supports discontinuous mode operation below 0.6V VC with max 24µs off-time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 100V - supports wide-input isolated supplies including 36–72V telecom and 12–48V automotive systems. |
| Operating Junction Temp | –40°C to 150°C - qualified for high-temp automotive and industrial environments; higher than standard I-grade (125°C). |
| INTVCC Regulation | 7.0V ±0.2V - internally regulated bias rail enabling robust gate drive for external N-MOSFETs without external LDO. |
| Gate Drive Current | 1.9A avg source/sink - drives medium-power MOSFETs directly; rise/fall times ≤16ns (CL = 3.3nF) ensure fast switching. |
| SENSE Threshold Range | 90–110mV (max), 15mV (min) - sets precise current limit; ratio of max/min thresholds (5.2–8.2×) enables wide dynamic range control. |
| Soft-Start Threshold | 0.65V - defines start-up delay timing via external capacitor; clamps VC during ramp-up for controlled output rise. |
| EN/UVLO Threshold | 1.223V rising - programmable enable point via resistor divider; includes 2.4µA hysteresis current for stable turn-on/turn-off. |
Pinout & Package
LT3748HMS#PBF is housed in a 16-lead plastic MSOP package with four leads removed (12-pin functional layout), optimized for thermal performance (θJA = 90°C/W) and high-voltage isolation. The exposed pad is not electrically connected and may be left floating or grounded for mechanical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main input supply reference | Bypassed locally; powers startup circuitry and serves as reference for RFB feedback network. |
| EN/UVLO (3) | Enable and undervoltage lockout input | Resistor-divider programmed; sinks 2.4µA hysteresis current when falling below 1.223V. |
| INTVCC (5) | Internally regulated gate driver supply | 7V output; can be tied to VIN if ≤20V and no third winding used; requires local bypass capacitor. |
| GATE (6) | N-MOSFET gate driver output | Switches between INTVCC and GND; 0.05V VOL / (INTVCC – 0.05V) VOH ensures strong drive. |
| SENSE (7) | Primary-side current sense input | Kelvin-connected to RSENSE; monitors switch current for cycle-by-cycle limiting (90–110mV threshold). |
| GND (8,9) | Power and signal ground | Dual ground pins reduce noise coupling; connect to low-impedance ground plane near SENSE and RSENSE. |
| SS (10) | Soft-start timing node | Sources 5µA to external capacitor; switching begins when voltage reaches 0.65V. |
| VC (11) | Error amplifier compensation node | Connect series RC to ground for loop stability; 100pF parallel cap suppresses noise. |
| TC (12) | Temperature compensation current source | Sources 0.55V/RTC current into RREF to cancel diode VF drift over temperature. |
| RREF (14) | Reference resistor connection | Accepts 6.04kΩ (±4%) resistor; sets gain for flyback error amplifier; bias current <500nA. |
| RFB (16) | Feedback resistor connection | Connected to MOSFET drain; converts flyback pulse amplitude to current proportional to VOUT × NPS. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates opto-isolator and third winding - reduces BOM cost, improves reliability, avoids aging/nonlinearity issues. |
| Boundary conduction mode (BCM) | Enables zero-current switching per cycle - improves efficiency, allows smaller magnetics, prevents subharmonic oscillation. |
| Integrated 7V INTVCC regulator | Powers gate driver independently - removes need for auxiliary winding or external bias supply in most designs. |
| Programmable temperature compensation | TC pin current offsets diode VF drift - achieves ±5% total output regulation across –40°C to 150°C without secondary sensing. |
| AEC-Q100 qualified (H-grade) | Validated for automotive underhood applications - meets stress test requirements for high-temp reliability and lifetime. |
Applications
| Telecom Isolated DC/DC Converter | Automotive High-Temp Power Supply |
|---|---|
Use Scenario: 36–72V telecom rectified input converted to isolated 12V/2A for base station control logic. IC Role / Device Role / Timing Role: Primary-side flyback controller performing boundary-mode switching, output voltage sensing, and gate drive timing. Use Value: Achieves 25W output with <±1.5% load regulation across full input range - no opto-isolator required, reducing footprint and long-term drift risk. |
Use Scenario: 12V battery input (up to 16V surge) powering isolated 5V microcontroller domain in engine control unit. IC Role / Device Role / Timing Role: High-temp flyback controller managing gate timing, current limiting, and thermal-compensated regulation at 150°C junction. Use Value: Maintains stable 5V output across –40°C to 125°C ambient with AEC-Q100 H-grade qualification - eliminates need for secondary feedback in harsh environments. |
| Industrial Isolated Auxiliary Supply | Military-Grade DC/DC Module |
Use Scenario: 24–48V industrial bus powering isolated 15V/1A supply for analog sensor front-end and ADC reference. IC Role / Device Role / Timing Role: Flyback controller executing primary-side feedback sampling at zero-secondary-current crossing. Use Value: Delivers <1% line/load regulation with 400ns minimum sampling window - enables compact transformer design and high PSRR. |
Use Scenario: 28V aircraft bus (with 100V transients) powering isolated 28V/0.5A supply for avionics interface circuits. IC Role / Device Role / Timing Role: High-reliability flyback controller supporting 100V absolute max VIN and 150°C operation with extended life testing. Use Value: Survives MIL-STD-704E transients and maintains regulation under thermal shock - validated for military-grade power modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMS#PBF | Same architecture and pinout; rated for –40°C to 125°C junction (vs. 150°C for H-grade). | Suitable for commercial/industrial applications without extreme thermal stress. | Select LT3748IMS#PBF where ambient temperature remains ≤85°C and automotive qualification is not required. |
| UCC28911DR | TI flyback controller with integrated 700V MOSFET; fixed 70kHz frequency; no primary-side sensing - requires opto-coupler or auxiliary winding. | Lower BOM count due to integrated FET but lacks primary-side regulation and high-temp rating. | Choose UCC28911DR only for cost-sensitive, lower-power (<10W), non-automotive designs where opto-isolation is acceptable. |
Compared with LT3748IMS#PBF, the LT3748HMS#PBF adds guaranteed 150°C operation and AEC-Q100 compliance for underhood use; compared with UCC28911DR, it offers superior regulation accuracy, wider input range, and true primary-side sensing - critical for high-reliability isolated supplies.
Availability
LT3748HMS#PBF is available at Aetrix Electronics and suitable for telecom power systems, automotive ECU auxiliary supplies, and industrial isolated DC/DC converters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3748HMS#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 is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, automotive, and communications markets.
The LT3748HMS#PBF belongs to Analog Devices' high-voltage isolated power controller product line, engineered specifically for primary-side regulated flyback topologies in space-constrained, thermally demanding applications where reliability and regulation accuracy are critical.
FAQ
What is the maximum operating junction temperature of the LT3748HMS#PBF?
The LT3748HMS#PBF is specified for continuous operation from –40°C to 150°C junction temperature. This H-grade rating exceeds standard industrial (125°C) and qualifies the device for underhood automotive applications per AEC-Q100. Thermal derating above 125°C is recommended to ensure long-term reliability.
Does the LT3748HMS#PBF require an opto-isolator or third winding for regulation?
No, the LT3748HMS#PBF does not require an opto-isolator or third winding. It achieves precise output regulation by sampling the primary-side flyback waveform at the MOSFET drain during zero-secondary-current crossing - a core feature of its primary-side sensing architecture.
How is output voltage set on the LT3748HMS#PBF?
The LT3748HMS#PBF sets output voltage using two external resistors: RREF (typically 6.04kΩ) connected to ground and RFB connected to the MOSFET drain. The ratio RFB/RREF, multiplied by the internal 1.223V bandgap reference and divided by the transformer turns ratio, determines VOUT - with optional TC pin compensation for diode VF drift.
What package type and lead count does the LT3748HMS#PBF use?
The LT3748HMS#PBF uses a 16-lead plastic MSOP package with four leads removed (12 functional pins), designated as "MSOP-16 (12-lead)". The package includes an exposed thermal pad that may be left unconnected or grounded for mechanical stability, with θJA = 90°C/W.
Can the LT3748HMS#PBF drive high-side or synchronous rectifier MOSFETs?
No, the LT3748HMS#PBF is a low-side N-channel MOSFET gate driver only. It cannot directly drive high-side switches or synchronous rectifiers. Its GATE pin outputs a ground-referenced signal swinging between INTVCC and GND - intended exclusively for driving the source-grounded N-MOSFET in the primary-side switch leg.
LT3748HMS#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3748HMS#PBF FAQ
1.How can I place an order for LT3748HMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3748HMS#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 LT3748HMS#PBF reliable?
The price and inventory of LT3748HMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3748HMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3748HMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3748HMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3748HMS#PBF?
LT3748HMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3748HMS#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 LT3748HMS#PBF?
For technical support, including LT3748HMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3748HMS#PBF requirements.
6.How does Aetrix verify that LT3748HMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3748HMS#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 LT3748HMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3748HMS#PBF?
All LT3748HMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3748HMS#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 LT3748HMS#PBF part is unused and in its original packaging.
Return procedure for LT3748HMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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