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Analog Devices Inc. LTC3766HGN#PBF
- Part No.:
- LTC3766HGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3766HGN#PBF.pdf
- Description:
- IC CONTROLLER SYNCH 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,033
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Product details
Overview
LTC3766HGN#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, secondary-side synchronous forward controller optimized for isolated active-clamp DC/DC converters. It delivers precise average current limiting (±8 mV threshold accuracy), Direct Flux Limit™ protection against transformer saturation, and clean start-up into pre-biased loads - enabling robust 5V/15A battery charger designs in telecom and industrial systems.
For engineers reviewing the LTC3766HGN#PBF datasheet, LTC3766HGN#PBF pinout, LTC3766HGN#PBF application, or LTC3766HGN#PBF equivalent, this page provides verified functional context, validated package mapping to 28-lead narrow SSOP, confirmed thermal rating (–40°C to 150°C), and real-world design implications of its PolyPhase-capable architecture, dual linear regulator control, and adaptive gate timing.
Technical Context
The LTC3766HGN#PBF implements secondary-side PWM control with integrated volt-second limiting (ΔVSEC(TH) = ±6% accuracy), precision current sensing (VISAVG = 55 mV typ. in resistor-sense mode), and adaptive dead-time management via SGD/FGD pins. Its error amplifier features gm = 2.7 mS and REA = 5 MΩ, supporting stable loop compensation across wide load transients.
It operates in two voltage modes (LV/HV) set by the MODE pin, adjusting VCC regulation (7.0 V / 8.5 V), UVLO thresholds (4.7 V / 7.9 V rising), and VAUX switchover points (4.7 V / 7.65 V). The FS/SYNC pin enables either internal oscillator operation (fHIGH = 275 kHz typ.) or PLL synchronization (100–500 kHz range) with 20 µA sourcing capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VFB Regulated Voltage | 0.600 V ±8 mV - sets output voltage accuracy; enables tight regulation at 5 V with ±0.8% tolerance over temp. |
| Average Current Sense Threshold | 55 mV (RS mode) - defines precise average current limit; supports accurate 15 A output current control without external gain. |
| Max Duty Cycle | 79% - constrains maximum on-time to prevent core saturation in forward topology with active clamp reset. |
| Operating Junction Temp | –40°C to 150°C - qualified for harsh environments including automotive under-hood and industrial power systems. |
| Package Thermal Resistance | θJA = 95°C/W (SSOP) - determines heatsink requirements; requires careful PCB copper pour for 150°C operation. |
| SW Pin Clamp Voltage | 51 V - protects internal circuitry during MOSFET switching transients; eliminates need for external clamping diodes. |
| FS/SYNC Frequency Range | 100–500 kHz (PLL sync) - allows synchronization to system clock for EMI reduction in multi-rail power supplies. |
Pinout & Package
Package: 28-lead narrow plastic SSOP (GN), exposed pad soldered to GND for thermal performance (θJA = 95°C/W). Pin 14 and exposed pad (Pin 29) are signal/power ground; Pin 27 is PGND (Kelvin sense for SG reverse current).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SG (Pin 1) | Synchronous MOSFET gate driver output | Drives low-side synchronous rectifier; pull-down R = 1.0 Ω ensures fast turn-off to minimize conduction loss. |
| FG (Pin 2) | Forward MOSFET gate driver output | Drives high-side forward switch; pull-up R = 1.5 Ω balances rise/fall times for ZVS optimization. |
| VSEC (Pin 3) | Volt-second limit input | Monitors SW node integral; terminates PWM on-time before transformer saturation - no compromise on transient response. |
| MODE (Pin 4) | LV/HV operating mode select | GND = 7 V VCC mode (for 5–10 V gate drive); VCC = 8.5 V mode (for 12 V logic-level MOSFETs). |
| FB (Pin 6) | Inverting input of main error amplifier | Connects to remote sense network; 0.6 V reference enables direct 5 V output regulation with minimal external components. |
| ITH (Pin 7) | Error amplifier output | Hosts Type II/III compensation network; gm = 2.7 mS supports stable loop bandwidth up to ~100 kHz. |
| RUN (Pin 8) | Enable/shutdown control with hysteresis | 1.22 V rising threshold; 1.17 V falling threshold - enables precise handoff from primary-side startup to secondary control. |
| IS+ / IS– (Pins 18/17) | Differential current sense inputs | Supports both resistor-shunt (55 mV threshold) and current transformer sensing; IS– tied to VCC enables single-ended CT mode. |
| VSOUT / VS+ / VS– (Pins 11–13) | True remote differential sense amplifier outputs/inputs | ADA = 1.0 V/V, CMRR = 75 dB - rejects common-mode noise on long PCB traces; critical for <1% output voltage accuracy. |
| FS/SYNC (Pin 15) | Oscillator frequency set / PLL sync input | Sources 20 µA; resistor-to-GND sets fOSC (75–500 kHz); external clock input enables deterministic EMI shaping. |
| REGSD (Pin 16) | Linear regulator shutdown timer | Capacitor-to-GND sets timeout; 1.21 V threshold disables HV linear regulator after safe bias establishment - prevents overvoltage stress. |
| SGD / FGD (Pins 19/20) | Adaptive gate delay controls | Resistor-to-GND sets dead time between PT+/PT– and SG/FG edges; minimizes shoot-through while preserving ZVS conditions. |
| NDRV (Pin 21) | External pass device driver | Drives base/gate of NPN/MOSFET pass transistor for HV linear regulator; enables >32 V input bias generation. |
| VIN (Pin 22) | High-voltage bias input | 5–32 V range powers internal monitoring circuits and HV linear regulator controller; clamped at 30 V for fault protection. |
| SW (Pin 23) | Kelvin connection to synchronous MOSFET drain | Enables adaptive blanking, leading-edge suppression, and SG reverse-current detection; internal 50 V clamp avoids external TVS. |
| VAUX (Pin 24) | Auxiliary LDO input | 5–15 V input powers internal 15 V LDO; activates when VAUX > 4.7 V (LV) or > 7.65 V (HV), bypassing VIN regulator for efficiency. |
| PT+ / PT– (Pins 25/26) | Pulse transformer encoded PWM outputs | Transmit duty-cycle and phase information across isolation barrier to LTC3765; support standalone mode with standard PWM on PT+. |
| PGND (Pin 27) | Power ground for gate drivers | Must connect to source of synchronous MOSFET - separates high di/dt return path from signal ground to reduce noise coupling. |
| VCC (Pin 28) | Main supply for control and drivers | 5–10 V regulated output powers all internal circuitry; sourced from VAUX LDO or external HV linear regulator per MODE setting. |
Key Features
| Feature | Design Value |
|---|---|
| Direct Flux Limit™ | Guarantees no transformer saturation by terminating PWM on-time based on real-time volt-second integral - preserves transient response without sacrificing reliability. |
| True Remote Differential Sensing | VSOUT amplifier with 75 dB CMRR and 0.99–1.01 V/V gain enables sub-10 mV output voltage error over full load/line/temp range. |
| Clean Start-Up into Pre-Biased Load | Controlled soft-start sequence initiated only after RUN pin exceeds 1.22 V - prevents output voltage overshoot when powering live bus systems. |
| Self-Starting Architecture with LTC3765 | Eliminates need for separate auxiliary bias supply; primary-side LTC3765 handles open-loop startup until secondary-side bias reaches operational threshold. |
| Dual Linear Regulator Control | Flexible bias generation: VAUX LDO (15 V) or external HV linear regulator (via NDRV) - selectable via MODE pin to match MOSFET gate drive requirements. |
| Synchronous MOSFET Reverse Current Limit | SW pin monitoring detects reverse conduction; triggers immediate FG turn-off and SG turn-on to clamp reverse current - protects rectifiers during light-load transitions. |
Applications
| Isolated Telecom Power Supply | High-Power Battery Charger |
|---|---|
|
Use Scenario: 36–72 V input isolated DC/DC converter delivering 5 V/15 A to telecom shelf management systems with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: Secondary-side PWM controller managing synchronous rectification, volt-second limiting, and remote sensing - directly regulates output voltage and current at point-of-load. Use Value: Achieves 94% efficiency at 48 VIN/15 AOUT while eliminating transformer saturation risk and enabling clean start-up into pre-biased backplane rails. |
Use Scenario: Isolated 48 V battery charging system for EV service equipment requiring precise constant-current/constant-voltage profiles and high reliability. IC Role / Device Role / Timing Role: Core controller implementing average current limiting (55 mV threshold), pre-biased start-up, and overtemperature protection - ensures safe charge termination and cell balancing integrity. Use Value: Precision current limit accuracy (±8 mV) and Direct Flux Limit™ enable repeatable 15 A charge cycles without core derating or thermal shutdown events. |
| Avionics DC/DC Converter | Military Vehicle Power System |
|
Use Scenario: 28 V aircraft bus-fed isolated converter supplying 5 V/10 A to flight control computers with MIL-STD-704 compliance and extended temperature operation. IC Role / Device Role / Timing Role: Secondary-side controller with –40°C to 150°C qualification, remote sensing, and PLL-sync capability - maintains regulation under wide input transients and vibration-induced noise. Use Value: 95°C/W θJA and 150°C TJMAX allow conduction-cooled mounting; FS/SYNC PLL sync reduces conducted EMI in sensitive avionics bays. |
Use Scenario: Ruggedized 24/28 V vehicle power system converting to isolated 5 V for mission-critical C4I subsystems operating in extreme ambient temperatures. IC Role / Device Role / Timing Role: Robust forward controller with overvoltage/overtemperature protection, adaptive dead-time control, and self-starting architecture - sustains operation during engine cranking dips and hot-soak conditions. Use Value: RUN pin hysteresis (1.22 V on / 1.17 V off) enables reliable restart after brownouts; internal 50 V SW clamp withstands load-dump transients without external protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar secondary-side synchronous forward controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3766IGN#PBF | Same pinout and functionality; rated for –40°C to 125°C junction temperature (vs. 150°C for LTC3766HGN#PBF). | Not suitable for sustained 150°C ambient or high-power density designs requiring extended thermal margin. | Select LTC3766HGN#PBF when operating junction temperature exceeds 125°C or when designing for military/automotive under-hood use cases. |
| LTC3766HUFD#PBF | Identical electrical specs and temperature rating; packaged in 4 mm × 5 mm QFN (UFD) with θJA = 43°C/W (vs. 95°C/W for SSOP). | Better thermal performance enables higher power density but requires re-layout due to different footprint and exposed pad location. | Choose LTC3766HUFD#PBF for space-constrained, thermally demanding applications where PCB area and thermal resistance are prioritized over legacy SSOP compatibility. |
Compared with LTC3766IGN#PBF, the LTC3766HGN#PBF provides 25°C higher maximum junction temperature for enhanced reliability in high-ambient environments; compared with LTC3766HUFD#PBF, it offers drop-in compatibility with existing SSOP layouts but requires more board area and thermal management effort.
Availability
LTC3766HGN#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 with guaranteed 150°C operation and long-term obsolescence planning.
Supply support for LTC3766HGN#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 technical and manufacturing continuity for all Linear power products, including rigorous AEC-Q200-aligned testing for high-reliability applications.
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 industrial power systems where fast transient response and transformer protection are critical.
FAQ
What is the maximum operating junction temperature for the LTC3766HGN#PBF?
The LTC3766HGN#PBF is fully specified and guaranteed over an operating junction temperature range of –40°C to 150°C. This H-grade qualification enables deployment in high-ambient environments such as automotive under-hood locations, industrial motor drives, and military vehicle power systems where thermal margins exceed standard commercial or industrial grades. The SSOP package has θJA = 95°C/W, so proper PCB thermal design is essential to maintain TJ ≤ 150°C.
How does the Direct Flux Limit™ function work in the LTC3766HGN#PBF?
The Direct Flux Limit™ in the LTC3766HGN#PBF monitors the volt-second product applied to the main power transformer via the VSEC pin. An internal integrator accumulates VSW × t, and when the resulting voltage exceeds a precision threshold (±6% accuracy), the PWM on-time is immediately terminated - preventing core saturation without compromising transient response speed. This is implemented entirely on the secondary side, eliminating reliance on primary-side timing estimates.
Can the LTC3766HGN#PBF operate without the LTC3765 primary-side controller?
Yes - the LTC3766HGN#PBF supports standalone operation when the MODE pin is biased with a 100 kΩ or 50 kΩ resistor to GND. In this mode, PT+ outputs a standard PWM signal (not pulse-encoded), PT– generates a reference clock, and FGD is ignored. However, full benefits - including self-starting architecture, active-clamp control, and isolation barrier communication - require pairing with the LTC3765 as intended in the reference design.
What are the key differences between the VAUX and VIN power domains in the LTC3766HGN#PBF?
In the LTC3766HGN#PBF, VAUX (5–15 V) powers an internal 15 V LDO that supplies VCC, while VIN (5–32 V) powers the high-voltage linear regulator controller and internal monitoring circuits. When VAUX exceeds its switchover threshold (4.7 V LV / 7.65 V HV), the VAUX LDO activates and the VIN-based regulator shuts down - improving efficiency. If only VAUX is used, tie NDRV to VCC and VIN to VAUX to disable the HV regulator entirely.
Does the LTC3766HGN#PBF support PolyPhase® operation, and how is it configured?
Yes - the LTC3766HGN#PBF is PolyPhase-capable. To configure master/slave operation, tie the FB pin of slave controllers to VCC (or >2.5 V) to disable their error amplifiers, while connecting PHASE and FS/SYNC pins across all phases for synchronized interleaving. This reduces input/output ripple and eases thermal management in high-power (>30 A) systems, leveraging the device's inherent phase-control logic and matched current-sense accuracy.
LTC3766HGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Direct Flux Limit™, PolyPhase®
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- 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:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC3766HGN#PBF FAQ
1.How can I place an order for LTC3766HGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3766HGN#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 LTC3766HGN#PBF reliable?
The price and inventory of LTC3766HGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3766HGN#PBF is usually 5 days.
3.What payment methods are accepted for LTC3766HGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3766HGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3766HGN#PBF?
LTC3766HGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3766HGN#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 LTC3766HGN#PBF?
For technical support, including LTC3766HGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3766HGN#PBF requirements.
6.How does Aetrix verify that LTC3766HGN#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3766HGN#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 LTC3766HGN#PBF meets industry standards.
7.What is the process for return or replacement of LTC3766HGN#PBF?
All LTC3766HGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3766HGN#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 LTC3766HGN#PBF part is unused and in its original packaging.
Return procedure for LTC3766HGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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