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Analog Devices Inc. LTC3766MPUFD#PBF
- Part No.:
- LTC3766MPUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3766MPUFD#PBF.pdf
- Description:
- IC CONTROLLER SYNCH 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,040
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Product details
Overview
LTC3766MPUFD#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, secondary-side synchronous forward controller IC designed for isolated active-clamp DC/DC converters. It delivers precise average current limiting (±5% accuracy), Direct Flux Limit™ protection against transformer saturation, and clean pre-biased load start-up - enabling robust 5V/15A battery charger designs in telecom and industrial systems.
For engineers reviewing the LTC3766MPUFD#PBF datasheet, LTC3766MPUFD#PBF pinout, LTC3766MPUFD#PBF application, or LTC3766MPUFD#PBF equivalent, key selection criteria include its –55°C to 150°C extended temperature rating, 28-lead 4mm × 5mm QFN package with exposed thermal pad, dual-mode linear regulator control (LV/HV), and PolyPhase® capability for multi-phase scaling.
Technical Context
The LTC3766MPUFD#PBF implements secondary-side PWM control with adaptive shoot-through prevention, leading-edge blanking on the SW pin, and integrated volt-second limit circuitry referenced to VSEC. Its error amplifier (gm = 2.7 mS) drives ITH for loop compensation, while the FS/SYNC pin supports both resistor-set oscillator operation (75–500 kHz) and PLL synchronization (100–500 kHz).
It features true remote differential sensing via VS+, VS–, and VSOUT pins with 0.99–1.01 V/V gain and 75 dB CMRR, plus dedicated reverse-current protection for the synchronous MOSFET using SG/IS+/IS–/SW monitoring. The MODE pin selects LV (7.0 V VCC) or HV (8.5 V VCC) gate drive levels, adjusting UVLO thresholds and VAUX switchover points accordingly.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Temp Range | –55°C to 150°C - qualified for military, avionics, and harsh-environment industrial use. |
| Feedback Voltage | 0.600 V ±1.3% - enables precise 5V output regulation with minimal external tolerance impact. |
| Average Current Sense | 0.73 V (CT mode) or 55 mV (RS mode) - supports accurate peak-to-average ripple cancellation via IPK pin. |
| Oscillator Range | 75–500 kHz - programmable via RFS/SYNC or synchronizable to external clock for EMI reduction. |
| Volt-Second Limit Acc. | ±4% (5–40 V SW range) - guarantees no transformer saturation without sacrificing transient response. |
| Gate Driver RDOWN | 1.0 Ω (FG/SG) - ensures fast turn-off of high-side synchronous rectifiers in high-current forward topologies. |
| Soft-Start Charge | 5 μA - allows predictable, capacitor-controlled ramp time for controlled inrush into pre-biased loads. |
Pinout & Package
Package: 28-lead (4 mm × 5 mm) plastic QFN with exposed thermal pad (Pin 29 = GND). Requires soldering of exposed pad for θJA = 43°C/W thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SG (Pin 26) | Synchronous MOSFET gate driver output | Drives low-side synchronous rectifier; monitored via SW/IS+ for reverse-current protection. |
| FG (Pin 27) | Forward MOSFET gate driver output | Drives primary-side forward switch; timing coordinated with PT+ via FGD delay resistor. |
| VSEC (Pin 28) | Volt-second integrator input | Terminates PWM on-time when internal threshold exceeded - prevents core saturation. |
| MODE (Pin 1) | LV/HV operating mode selector | GND = 7.0 V VCC / 4.7 V UVLO; VCC = 8.5 V VCC / 7.9 V UVLO - matches MOSFET gate drive needs. |
| VS+, VS–, VSOUT (Pins 8–10) | Remote differential sense inputs/output | Enables Kelvin sensing at load; VSOUT sources ≤3 mA - avoids ground-loop errors in high-precision outputs. |
| REGSD (Pin 13) | Linear regulator shutdown timer | Capacitor-to-ground sets max enable time for HV linear regulator; shuts down if VAUX fails to rise. |
| SW (Pin 20) | Synchronous MOSFET drain monitor | Used for adaptive blanking, ripple cancellation, and SG reverse-current detection; clamped to 50 V. |
Key Features
| Feature | Design Value |
|---|---|
| Direct Flux Limit™ | Hardware-based volt-second monitoring eliminates need for complex transformer reset timing design. |
| Clean pre-biased start-up | Controlled soft-start sequence initiates only after RUN pin exceeds 1.22 V - prevents output voltage overshoot. |
| Dual linear regulator architecture | VAUX LDO (15 V) + VIN-based HV controller - enables flexible bias generation with automatic switchover. |
| PolyPhase® operation support | PHASE and FB pins allow master/slave configuration across multiple LTC3766 units for >30 A output scaling. |
| True remote differential sensing | VS+, VS–, VSOUT provide 75 dB CMRR and 0.99–1.01 gain - maintains ±0.5% output regulation under PCB trace IR drop. |
Applications
| Isolated Telecom Power Supply | High-Power Battery Charger |
|---|---|
|
Use Scenario: 36–72 V input isolated 5 V/15 A supply for 48 V telecom shelf management systems. IC Role / Device Role / Timing Role: Secondary-side PWM controller coordinating FG/SG timing, volt-second limiting, and remote sensing. Use Value: Achieves 94% efficiency at 48 VIN/15 AOUT while guaranteeing no transformer saturation during line transients. |
Use Scenario: Industrial Li-ion battery charging system requiring clean start-up into pre-biased bus. IC Role / Device Role / Timing Role: Precision average current limiter with ripple-compensated IS+ sensing and adaptive dead-time control. Use Value: Enables constant-current charging with ±1% current accuracy and zero output voltage undershoot during cold start. |
| Avionics DC/DC Converter | Military Vehicle Power System |
|
Use Scenario: 28 V aircraft bus to 5 V isolated supply for flight control electronics with MIL-STD-704 compliance. IC Role / Device Role / Timing Role: Robust secondary-side controller with –55°C to 150°C operation and overtemperature/overvoltage protection. Use Value: Maintains regulation during wide-input transients and survives thermal cycling without derating. |
Use Scenario: 24 V/28 V vehicle platform powering ruggedized computing modules requiring isolated 5 V rails. IC Role / Device Role / Timing Role: Self-starting forward controller working with LTC3765 to eliminate separate bias supply. Use Value: Reduces BOM count by integrating linear regulator control, remote sensing, and flux limiting in one IC. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar secondary-side forward controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3766HUFD#PBF | Same pinout and function; rated for –40°C to 150°C (not –55°C). | Lacks extended cold-start capability below –55°C required in space or arctic deployments. | Select LTC3766MPUFD#PBF when full military-grade temperature range is mandatory. |
| LTC3766IUFD#PBF | Same package; rated for –40°C to 125°C; lower cost; identical electrical specs at 25°C. | Not qualified for operation below –40°C or above 125°C - unsuitable for avionics or heavy equipment. | Choose LTC3766IUFD#PBF only for commercial/industrial applications within standard temp range. |
Compared with LTC3766HUFD#PBF and LTC3766IUFD#PBF, the LTC3766MPUFD#PBF uniquely supports –55°C startup and sustained operation to 150°C, making it the sole option for MIL-PRF-38534 Class H or space-qualified forward converter designs where extended thermal margin is non-negotiable.
Availability
LTC3766MPUFD#PBF is available at Aetrix Electronics and suitable for isolated telecom power supplies, high-power battery chargers, and avionics DC/DC converters requiring stable component supply across extended temperature extremes.
Supply support for LTC3766MPUFD#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 acquired Linear Technology in 2017 and maintains full product support, datasheet archives, and application engineering for legacy Linear parts including the LTC3766 family.
The LTC3766 product line was designed specifically for high-efficiency, isolated active-clamp forward converters with secondary-side control - targeting telecom, battery charging, and ruggedized power systems where fast transient response and transformer protection are critical.
FAQ
What is the maximum operating junction temperature for the LTC3766MPUFD#PBF?
The LTC3766MPUFD#PBF is tested and guaranteed over an operating junction temperature range of –55°C to 150°C. Its QFN package has θJA = 43°C/W when the exposed pad (Pin 29) is properly soldered to PCB ground. Thermal design must ensure TJ does not exceed 150°C under worst-case ambient and power dissipation conditions, as lifetime is derated above 125°C.
How does the LTC3766MPUFD#PBF implement Direct Flux Limit™?
The LTC3766MPUFD#PBF implements Direct Flux Limit™ by integrating a precision volt-second integrator on the VSEC pin. A resistor from SW to VSEC and capacitor from VSEC to GND set the integration time constant. When the VSEC voltage crosses an internal threshold (±4% accuracy over 5–40 V SW range), the PWM on-time is terminated - preventing transformer saturation without compromising transient response or requiring external timing components.
Can the LTC3766MPUFD#PBF operate without the LTC3765 primary-side controller?
Yes - the LTC3766MPUFD#PBF supports standalone operation when the MODE pin is tied to GND through a 100 kΩ (LV) or 50 kΩ (HV) resistor. In this mode, PT+ outputs a standard PWM signal for direct primary MOSFET drive, PT– generates a reference clock, and FGD functionality is disabled. However, full isolated active-clamp functionality requires the LTC3765.
What is the purpose of the REGSD pin on the LTC3766MPUFD#PBF?
The REGSD pin on the LTC3766MPUFD#PBF serves as a safety timer for the high-voltage linear regulator controller. A capacitor from REGSD to GND sets the maximum allowable time for the regulator to remain active. When the REGSD voltage reaches 1.21 V (sourced at 13 μA), the linear regulator shuts down - preventing uncontrolled bias generation if VAUX fails to rise or the external pass device malfunctions.
Does the LTC3766MPUFD#PBF support PolyPhase® operation, and how is it configured?
Yes, the LTC3766MPUFD#PBF supports PolyPhase® operation for current sharing across multiple phases. Configuration requires connecting the PHASE pin of slave units to the PHASE pin of the master, tying FB of slaves to VCC (or >2.5 V), and synchronizing all units via a common FS/SYNC clock. This enables seamless scaling beyond 15 A while maintaining tight voltage and current regulation across phases.
LTC3766MPUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Direct Flux Limit™, PolyPhase®
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Applications:
- Synchronous Forward Controller
- Voltage - Input:
- 5V ~ 32V
- Voltage - Supply:
- 5V ~ 10V
- Current - Supply:
- 5 mA
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3766MPUFD#PBF FAQ
1.How can I place an order for LTC3766MPUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3766MPUFD#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 LTC3766MPUFD#PBF reliable?
The price and inventory of LTC3766MPUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3766MPUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3766MPUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3766MPUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3766MPUFD#PBF?
LTC3766MPUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3766MPUFD#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 LTC3766MPUFD#PBF?
For technical support, including LTC3766MPUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3766MPUFD#PBF requirements.
6.How does Aetrix verify that LTC3766MPUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3766MPUFD#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 LTC3766MPUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3766MPUFD#PBF?
All LTC3766MPUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3766MPUFD#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 LTC3766MPUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3766MPUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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