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Analog Devices Inc. LT3748IMS#TRPBF
- Part No.:
- LT3748IMS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3748IMS#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,677
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Product details
Overview
LT3748IMS#TRPBF from Analog Devices is a 100V isolated flyback controller IC designed for primary-side regulation in high-power 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 in telecom and industrial power supplies.
For engineers reviewing the LT3748IMS#TRPBF datasheet, LT3748IMS#TRPBF pinout, LT3748IMS#TRPBF application, or LT3748IMS#TRPBF equivalent, key selection criteria include its 16-lead MSOP package, 1.9A gate drive capability, programmable UVLO and soft-start, primary-side voltage sensing via RFB/RREF, and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT3748IMS#TRPBF implements boundary-mode (critical conduction) control using a flyback waveform sampling architecture that directly derives output voltage information from the primary-side drain voltage during zero-current crossing-enabling precise regulation without optocouplers or auxiliary windings. Its internal error amplifier references a 1.223V bandgap and uses RFB/RREF resistor ratio to set VOUT.
It features dual current-limit thresholds (90–110mV typical SENSE trip), programmable temperature compensation via TC/RTC, and a 7V regulated INTVCC supply with 0.7V dropout at 10mA. Gate drive operates with 250ns minimum on-time and 700ns minimum off-time, supporting variable-frequency operation tied to load and transformer inductance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 100V - supports wide-input industrial, telecom, and automotive battery systems without pre-regulation. |
| INTVCC Regulation | 7.0V ±0.2V - powers internal gate driver and logic; stable bias enables robust MOSFET switching up to 100V input. |
| Gate Drive Capability | 1.9A avg source/sink - drives high-Ciss MOSFETs for multi-watt isolated outputs with fast 16ns rise/fall times. |
| SENSE Threshold | 90–110mV (typ) - sets peak primary current limit; adjustable via RSENSE for precise power scaling and overcurrent protection. |
| Operating Mode | Boundary mode - ensures zero-current switching each cycle, minimizing transformer size and eliminating subharmonic oscillation. |
| Temperature Range | –40°C to +125°C - qualified for industrial and automotive environments; junction-limited operation up to 150°C for I-grade variants. |
| UVLO Threshold | 1.223V rising (±2.5%) - programmable enable via resistor divider; includes 2.4µA hysteresis current for clean startup/shutdown. |
Pinout & Package
The LT3748IMS#TRPBF is housed in a 16-lead plastic MSOP package with four leads removed (12-pin functional layout), optimized for high-voltage isolation and thermal dissipation in compact flyback designs.
| 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 & undervoltage lockout input | Resistor-divider programmed threshold (1.223V) controls startup; sinks 2.4µA for hysteresis. |
| INTVCC (5) | Internally regulated gate driver supply | 7V output; powers GATE driver; may 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 drive strength supports high-power discrete switches. |
| SENSE (7) | Primary-side current sense input | Kelvin-connected to RSENSE source; monitors peak current for cycle-by-cycle limiting (90–110mV threshold). |
| GND (8,9) | Power and signal ground | Dual pins reduce ground impedance; critical for noise immunity in high-dV/dt flyback circuits. |
| SS (10) | Soft-start timing capacitor node | Sources 5µA to external C; startup delayed until VSS reaches ~0.65V, preventing inrush. |
| VC (11) | Error amplifier compensation node | Connect RC network to ground for loop stability; 155µmhos transconductance enables precise bandwidth control. |
| TC (12) | Temperature compensation current source | Sources 0.55V/RTC current into RREF to offset diode VF drift over temperature. |
| RREF (14) | Reference resistor connection | Accepts 6.04kΩ (±1%) resistor; forms ground-referred reference for output voltage calculation. |
| RFB (16) | Feedback resistor connection | Connected to transformer primary; RFB/RREF ratio × 1.223V × 1/NPS sets VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates opto-isolator and third winding-reduces BOM count, cost, and board space while improving long-term reliability. |
| Boundary mode control | Enables zero-current switching per cycle, yielding tight load regulation (<±1% typical), small magnetics, and inherent stability without slope compensation. |
| Programmable temperature compensation | TC pin current offsets diode forward-voltage drift, enabling <±5% total output regulation across –40°C to +125°C ambient. |
| AEC-Q100 qualified | LT3748IMS#TRPBF meets automotive stress testing requirements (Grade I: –40°C to +125°C), supporting under-hood and infotainment power supplies. |
| High-voltage gate drive | 1.9A average source/sink capability allows direct driving of 100V+ MOSFETs with minimal external components and low gate charge loss. |
Applications
| Isolated Telecom Supply | Automotive High-Voltage DC/DC |
|---|---|
Use Scenario: 36–72V telecom rectifier feeding isolated 12V/2A output for base station control logic. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via RFB sampling; sets switching frequency dynamically based on load and LPRI. Use Value: Achieves 25W output with <±1% line/load regulation, no opto-isolator aging, and compliance with EN55022 Class B EMI limits. | Use Scenario: 12V battery-backed 48V–12V isolated converter for ADAS camera module power. IC Role / Device Role / Timing Role: AEC-Q100 qualified controller managing boundary-mode switching and thermal compensation across engine bay temperatures. Use Value: Maintains stable 12V output over –40°C to +105°C ambient with <±3% total variation, eliminating secondary-side feedback complexity. |
| Industrial Isolated Sensor Power | Military Ruggedized PSU |
Use Scenario: 24V industrial bus powering isolated 5V/1A sensor interface with reinforced creepage/clearance. IC Role / Device Role / Timing Role: Regulates output using primary-side feedback; handles wide input transients (e.g., 24V ±20%) without latch-off. Use Value: Enables compact, certified (IEC 61000-4-5) design meeting 4kV surge immunity with single-transformer isolation. | Use Scenario: 28V aircraft bus supplying 15V/1.5A isolated rail for avionics data acquisition. IC Role / Device Role / Timing Role: High-reliability controller operating up to 125°C junction; supports MIL-STD-704A input compliance. Use Value: Delivers >90% efficiency at full load with extended lifetime (>100k hrs) due to absence of opto-isolator degradation mechanisms. |
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; no boundary mode; requires auxiliary winding for VDD; lower max input (85V). | Targeted at cost-sensitive consumer adapters; lacks primary-side VOUT sensing and TC compensation. | Choose UCC28911DR only if fixed-frequency operation and auxiliary winding are acceptable; not suitable for opto-free precision regulation. |
| MAX17690ATP+T | Current-mode flyback controller with integrated 100V MOSFET; fixed 660kHz frequency; no TC pin or programmable UVLO. | Designed for ultra-compact low-power supplies (<10W); lacks high-power gate drive and wide-input flexibility. | Select MAX17690ATP+T when board space is critical and output power ≤8W; unsuitable for 25W+ or automotive temperature range. |
Compared with UCC28911DR and MAX17690ATP+T, the LT3748IMS#TRPBF uniquely combines primary-side regulation without opto or third winding, boundary-mode efficiency optimization, and AEC-Q100 qualification-making it the only choice for high-reliability, high-power isolated supplies requiring minimal component count and wide temperature operation.
Availability
LT3748IMS#TRPBF 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 lifecycle support, and AEC-Q100 compliance.
Supply support for LT3748IMS#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 industrial, automotive, communications, and healthcare markets.
The LT3748IMS#TRPBF belongs to Analog Devices' Power by Linear™ isolated controller product line, engineered specifically for high-efficiency, opto-free flyback topologies in demanding environments where reliability, precision, and thermal robustness are critical.
FAQ
What is the maximum output power achievable with the LT3748IMS#TRPBF?
The LT3748IMS#TRPBF itself does not define maximum output power-it enables up to ~25W in typical implementations (e.g., 12V/2A) depending on external components. Key limiting factors include the selected MOSFET's voltage/current rating, transformer saturation current, output diode reverse voltage, and PCB thermal design. With appropriate 100V+ MOSFETs and optimized magnetics, the LT3748IMS#TRPBF has been validated in 25W telecom supplies; higher power requires careful attention to leakage inductance snubbing and thermal management.
Does the LT3748IMS#TRPBF require an optocoupler or third winding for regulation?
No, the LT3748IMS#TRPBF does not require an optocoupler or third winding. It achieves precise output regulation by sampling the primary-side flyback voltage waveform at the MOSFET drain during zero-current crossing. This primary-side sensing architecture-enabled by its proprietary boundary-mode detection and sampling error amplifier-is a core feature of the LT3748IMS#TRPBF and eliminates reliability concerns associated with opto aging and third-winding coupling inaccuracies.
How is output voltage set on the LT3748IMS#TRPBF?
Output voltage on the LT3748IMS#TRPBF is set using two external resistors: RREF (typically 6.04kΩ) connected to ground, and RFB connected between the transformer primary and the RFB pin. The relationship is VOUT ≈ (1.223V × RFB / RREF) × (1/NPS) − VF, where NPS is the primary-to-secondary turns ratio and VF is the output diode forward voltage. Temperature compensation is added via the TC pin and RTC resistor to offset VF drift.
What is the purpose of the TC pin on the LT3748IMS#TRPBF?
The TC (Temperature Compensation) pin on the LT3748IMS#TRPBF sources a current proportional to absolute temperature (ITC = 0.55V / RTC) into the RREF node. This positive temperature coefficient current counteracts the negative temperature coefficient of the output diode's forward voltage (VF), enabling stable output regulation across –40°C to +125°C ambient. Proper RTC selection-based on measured VF drift-is essential for achieving <±5% total output variation over temperature.
Is the LT3748IMS#TRPBF pin-compatible with other members of the LT3748 family?
Yes, the LT3748IMS#TRPBF shares identical pinout and footprint with all LT3748 variants (e.g., LT3748EMS#TRPBF, LT3748HMS#TRPBF, LT3748MPMS#TRPBF), all housed in the same 16-lead MSOP package with four leads removed. Differences lie solely in temperature grade (I-grade: –40°C to +125°C), internal test screening, and qualification level-not in electrical behavior or physical layout. This allows drop-in replacement for qualification upgrades without PCB redesign.
LT3748IMS#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3748IMS#TRPBF FAQ
1.How can I place an order for LT3748IMS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3748IMS#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 LT3748IMS#TRPBF reliable?
The price and inventory of LT3748IMS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3748IMS#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3748IMS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3748IMS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3748IMS#TRPBF?
LT3748IMS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3748IMS#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 LT3748IMS#TRPBF?
For technical support, including LT3748IMS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3748IMS#TRPBF requirements.
6.How does Aetrix verify that LT3748IMS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3748IMS#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 LT3748IMS#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3748IMS#TRPBF?
All LT3748IMS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3748IMS#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 LT3748IMS#TRPBF part is unused and in its original packaging.
Return procedure for LT3748IMS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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