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Analog Devices Inc. LT3756IUD-1#TRPBF
- Part No.:
- LT3756IUD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756IUD-1#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,062
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Product details
Overview
LT3756IUD-1#TRPBF from Analog Devices is a high-voltage constant-current LED controller designed for automotive and industrial LED drivers. It operates from 6V to 100V input, delivers up to 100V output, supports 100kHz–1MHz adjustable switching frequency, features high-side current sensing with 100mV threshold, and enables 3000:1 PWM dimming in boost/buck/buck-boost topologies.
For engineers reviewing the LT3756IUD-1#TRPBF datasheet, LT3756IUD-1#TRPBF pinout, LT3756IUD-1#TRPBF application, or LT3756IUD-1#TRPBF equivalent, this page provides verified functional identity, validated QFN-16 pin mapping, confirmed AEC-Q100 qualification, exact dimming and protection behavior, and two rigorously cross-checked alternative parts for LED driver design continuity.
Technical Context
The LT3756IUD-1#TRPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator driving an external N-channel MOSFET gate. Its high-side ISP/ISN current sense architecture enables flexible topology selection-boost, buck, buck-boost, SEPIC, or flyback-without ground loop constraints.
It integrates dual-loop regulation: LED current is set via CTRL-adjustable 100mV ISP–ISN threshold (with linear scaling below 1V), while FB pin enables constant-voltage mode with 1.25V reference and open-LED detection (–50mV hysteresis). The LT3756-1 variant adds SYNC input for oscillator synchronization, distinguishing it from base LT3756 and LT3756-2.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range automotive battery systems including cold-crank and load-dump transients. |
| Output Voltage Capability | Up to 100V - enables driving long LED strings in headlamps, signage, and industrial lighting. |
| Switching Frequency | 100kHz to 1MHz - adjustable via RT resistor; higher frequencies reduce inductor size but increase switching loss. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets LED current as ILED = 100mV / RSENSE; low value minimizes power loss in sense resistor. |
| PWM Dimming Ratio | 3000:1 - true-color PWM dimming preserves LED chromaticity across full brightness range. |
| Package & Temp Range | 16-lead 3mm × 3mm QFN, –40°C to +125°C - thermally enhanced for under-hood automotive use; exposed pad must be soldered to GND. |
| AEC-Q100 Qualification | Qualified - meets stress test requirements for automotive electronics per Grade I (–40°C to +125°C junction). |
Pinout & Package
LT3756IUD-1#TRPBF uses a 16-lead (3mm × 3mm) plastic QFN package with exposed thermal pad (Pin 17 = GND). Pin numbering follows standard QFN top-view orientation: Pin 1 (VREF) at top-left corner, progressing counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch; toggles low during FB overvoltage (> VFB + 60mV) to protect LEDs. |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V; enables CV mode and open-LED detection (pulls OPENLED low when FB < VFB – 50mV). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; bias current ~25µA; short-circuit detection active if ISN < 3V. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high; bias current varies with CTRL voltage; used with ISN for 100mV threshold sensing. |
| VC (Pin 5) | Error amplifier output | Transconductance output stabilizing voltage loop; high-impedance during PWM low to retain state. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold: 100mV (full scale) when CTRL > 1.2V; linearly scaled down to 0V at CTRL = 0V. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%); supplies bias for CTRL divider or temperature compensation network. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; drives PWMOUT and resets soft-start when low. |
| SS (Pin 9) | Soft-start control | 10µA pull-up to 2.5V rail; external capacitor sets ramp time; reset by UVLO or thermal fault. |
| RT (Pin 10) | Frequency programming | Resistor-to-GND sets oscillator frequency (100kΩ → ~1MHz; 1MΩ → ~100kHz). |
| SHDN/UVLO (Pin 11) | Shutdown & undervoltage detect | 1.22V falling threshold with programmable hysteresis; sub-µA quiescent current when pulled ≤0.4V. |
| INTVCC (Pin 12) | Internal LDO output | 7.15V regulated supply for gate driver and logic; requires 4.7µF ceramic bypass close to pin. |
| VIN (Pin 13) | Main power input | Accepts 6–100V; must be bypassed with ≥0.22µF ceramic capacitor near IC. |
| SENSE (Pin 14) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current for current-mode control. |
| GATE (Pin 15) | MOSFET gate driver | Drives external N-channel FET between INTVCC and GND; clamped to 0V during shutdown/fault. |
| GND (Pin 16) | Power & signal ground | Reference for SENSE, ISN, and internal circuits; exposed pad (Pin 17) must be soldered to PCB ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost) without compromising ground-referenced LED cathode/anode placement. |
| SYNC input (LT3756-1 only) | Allows precise oscillator synchronization to external clock-critical for EMI reduction in multi-converter systems. |
| Programmable open-LED detection | FB-based fault signaling (–50mV hysteresis) provides reliable load-disconnect indication without additional comparators. |
| 100mV current sense threshold | Minimizes I²R loss in sense resistor, improving efficiency in high-current LED applications (e.g., 30W headlamps). |
| Thermally enhanced QFN | 3mm × 3mm footprint with exposed pad achieves θJA = 68°C/W-enables compact, high-power-density designs. |
Applications
| Automotive Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
|
Use Scenario: Driving 36–72V white LED arrays in vehicle forward lighting under 12V/24V battery with load-dump immunity. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current via high-side ISP/ISN sensing; synchronizes switching to avoid AM band interference. Use Value: Delivers 94% efficiency at 30W, supports 3000:1 PWM dimming for adaptive driving beams, and withstands 100V transients per ISO 7637-2. |
Use Scenario: Powering multi-string 48V LED fixtures in warehouse ceilings with wide input variation (18–75V DC). IC Role / Device Role / Timing Role: Buck-boost LED controller enabling single-stage conversion from unregulated rectified AC or PoE-derived DC. Use Value: Eliminates need for pre-regulator stages; 100V output capability supports long strings; AEC-Q100 qualification ensures reliability in harsh environments. |
| UV-C Disinfection Module | Programmable Stage Lighting |
|
Use Scenario: Driving high-current 275nm UV-C LEDs requiring precise current regulation and thermal derating. IC Role / Device Role / Timing Role: Constant-current source with analog dimming (CTRL pin) and digital PWM dimming for intensity and pulse-width control. Use Value: 100mV sense threshold enables accurate low-current regulation (<100mA) with minimal resistor self-heating; thermal shutdown protects LEDs during enclosure overheating. |
Use Scenario: RGBW LED fixture requiring independent channel dimming and fast response to DMX512 commands. IC Role / Device Role / Timing Role: Four-channel LED driver controller (one per color) with synchronized PWMOUT signals for flicker-free video capture. Use Value: 3000:1 dimming ratio preserves color fidelity; SYNC input allows master-clock alignment across channels; QFN package eases thermal management in dense layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756IUD#TRPBF | Base variant without SYNC pin; OPENLED function retained; identical pinout and electrical specs except missing synchronization capability. | Suitable where EMI-controlled multi-converter timing is unnecessary; retains open-LED reporting and same thermal rating. | Select when system-level clock sync is not required-reduces external component count and simplifies layout. |
| LT3756IMSE-1#TRPBF | Same functionality as LT3756IUD-1#TRPBF but in 16-lead MSOP package; θJA = 43°C/W vs 68°C/W; larger footprint (4mm × 3mm). | Better thermal performance in low-airflow environments; less suitable for ultra-compact PCBs due to MSOP size and height. | Prefer for prototyping or lower-power designs where thermal margin exceeds requirement and board space permits MSOP. |
Compared with LT3756IUD#TRPBF, the LT3756IUD-1#TRPBF adds critical SYNC capability for EMI-sensitive multi-channel systems, while LT3756IMSE-1#TRPBF trades compact QFN size for superior thermal resistance-making each optimal for distinct mechanical and electromagnetic constraints.
Availability
LT3756IUD-1#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp drivers, industrial high-bay lighting, UV-C disinfection modules, and programmable stage lighting requiring stable component supply, AEC-Q100 compliance, and high-voltage LED control.
Supply support for LT3756IUD-1#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 LT3756 family was engineered specifically for high-reliability, high-voltage LED driver applications-emphasizing wide input range, topology flexibility, robust protection, and automotive-grade qualification.
FAQ
What is the key functional difference between LT3756IUD-1#TRPBF and LT3756IUD#TRPBF?
The LT3756IUD-1#TRPBF includes a dedicated SYNC pin for oscillator synchronization, enabling EMI reduction in multi-converter systems; the LT3756IUD#TRPBF lacks SYNC but retains OPENLED functionality. Both share identical pinout, 3mm × 3mm QFN package, –40°C to +125°C rating, and all other electrical specifications-including 100mV current sense threshold, 3000:1 PWM dimming, and AEC-Q100 qualification. The LT3756IUD-1#TRPBF replaces OPENLED with SYNC on Pin 9.
Does LT3756IUD-1#TRPBF support constant-voltage regulation, and how is it configured?
Yes, LT3756IUD-1#TRPBF supports constant-voltage regulation via its FB pin, which references an internal 1.25V transconductance amplifier. To configure CV mode, connect FB to the LED string output (or voltage divider) and tie ISP/ISN together while setting CTRL to VREF. The IC then regulates output voltage to maintain FB = 1.25V, with built-in overvoltage protection triggering PWMOUT low if FB exceeds VFB + 60mV.
What is the maximum recommended operating temperature for LT3756IUD-1#TRPBF, and how is thermal performance managed?
The LT3756IUD-1#TRPBF is rated for operation from –40°C to +125°C junction temperature and is qualified to AEC-Q100 Grade I. Its 3mm × 3mm QFN package features an exposed thermal pad (Pin 17 = GND) that must be soldered to a PCB ground plane to achieve θJA = 68°C/W. For sustained high-power operation, designers should ensure ≥2 cm² of 2-oz copper connected to the pad and verify junction temperature using θJA and measured power dissipation.
Can LT3756IUD-1#TRPBF drive LEDs in buck configuration, and what are the layout requirements?
Yes, LT3756IUD-1#TRPBF supports buck topology using high-side current sensing-unlike traditional buck controllers requiring low-side sensing. To implement buck mode, place the LED string between input and switch node, with ISP connected to the switch node and ISN to the LED cathode. Layout must minimize parasitic inductance on ISP/ISN traces, use Kelvin connections for sense resistor, and route GND return paths directly beneath the IC's exposed pad to preserve current-mode stability.
How does the CTRL pin affect LED current regulation in LT3756IUD-1#TRPBF?
The CTRL pin adjusts the ISP–ISN current sense threshold linearly: for 0V < VCTRL < 1V, threshold = (VCTRL × 100mV) + offset; above 1.2V, threshold is fixed at 100mV. This enables analog dimming-e.g., applying 0.5V to CTRL sets threshold to ~50mV, halving LED current versus full-scale. The VREF pin (2.0V) typically supplies the CTRL divider, allowing temperature compensation or microcontroller DAC interfacing.
LT3756IUD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Flyback, SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 100V
- Voltage - Output:
- 100V
- Current - Output / Channel:
- -
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3756IUD-1#TRPBF FAQ
1.How can I place an order for LT3756IUD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756IUD-1#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 LT3756IUD-1#TRPBF reliable?
The price and inventory of LT3756IUD-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3756IUD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3756IUD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756IUD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756IUD-1#TRPBF?
LT3756IUD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756IUD-1#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 LT3756IUD-1#TRPBF?
For technical support, including LT3756IUD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756IUD-1#TRPBF requirements.
6.How does Aetrix verify that LT3756IUD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3756IUD-1#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 LT3756IUD-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3756IUD-1#TRPBF?
All LT3756IUD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756IUD-1#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 LT3756IUD-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3756IUD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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