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Analog Devices Inc. LT3756IUD-2#TRPBF
- Part No.:
- LT3756IUD-2#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756IUD-2#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,316
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Product details
Overview
LT3756IUD-2#TRPBF from Analog Devices is a high-voltage constant-current LED controller designed for automotive and industrial lighting systems. It operates as a current-mode DC/DC controller driving external N-channel MOSFETs, supports 6V–100V input, delivers up to 100V output, enables 3000:1 PWM dimming, and features high-side current sensing for boost/buck/buck-boost topologies.
For engineers reviewing the LT3756IUD-2#TRPBF datasheet, LT3756IUD-2#TRPBF pinout, LT3756IUD-2#TRPBF application, or LT3756IUD-2#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification, 100mV high-side current sense threshold, programmable 100kHz–1MHz switching frequency, open LED protection via OPENLED pin, and thermally enhanced 3mm × 3mm QFN package with exposed GND pad.
Technical Context
The LT3756IUD-2#TRPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator, ground-referenced FB pin enabling dual constant-current/constant-voltage regulation, and dedicated ISP/ISN inputs for high-side LED current sensing. Its architecture supports topology flexibility-boost, buck, buck-boost, SEPIC, or flyback-without requiring level-shifting circuitry.
It integrates an improved OPENLED status pin (LT3756-2 variant), programmable soft-start via SS pin, undervoltage lockout with hysteresis on SHDN/UVLO, and analog dimming via CTRL pin that scales the 100mV current sense threshold linearly below 1V. The VC error amplifier output stabilizes loop response with external RC compensation.
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 headlamp, signage, and industrial lighting applications. |
| Current Sense Threshold | 100mV (typ) at ISP–ISN - provides precise, low-loss high-side current sensing with minimal power dissipation in sense resistor. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT pin resistor to optimize efficiency, EMI, or magnetic component size. |
| Dimming Ratio | 3000:1 true-color PWM dimming - maintains LED color fidelity across full brightness range without flicker or color shift. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade I for under-hood automotive environments. |
| Package | 16-lead 3mm × 3mm QFN with exposed GND pad - enables efficient thermal dissipation in compact PCB layouts. |
Pinout & Package
LT3756IUD-2#TRPBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17), rated for –40°C to +125°C operating junction temperature. The exposed pad must be soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives LED disconnect NMOS; toggles low during FB overvoltage (>VFB + 60mV) to protect LEDs. |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V nominal; enables constant-voltage mode and open LED detection (pulls OPENLED when FB < VFB – 50mV). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection when ISN < 3V and ISP–ISN > 150mV. |
| ISP (Pin 4) | Positive current sense input | High-side current sense input; bias current varies with CTRL voltage; used with ISN for 100mV threshold sensing. |
| VC (Pin 5) | Error amplifier output | Transconductance amplifier output; requires external RC network for loop stability and transient response. |
| CTRL (Pin 6) | Current threshold adjust | Scales ISP–ISN threshold from 0V to 100mV (linear below 1V); sets full-scale 100mV above 1.2V. |
| VREF (Pin 7) | 2V reference output | Stable 2V source (±2%); supplies bias for CTRL divider or temperature compensation networks; drives ≤100µA. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; controls oscillator, GATE, and PWMOUT; low state reduces IQ to <1µA. |
| OPENLED (Pin 9) | Open LED fault indicator | Open-collector output; pulls low when FB < VFB – 50mV (LT3756-2 feature); requires external <1mA pull-up. |
| SS (Pin 10) | Soft-start control | 10µA internal pull-up to 2.5V rail; external capacitor sets ramp time; reset by UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets switching frequency (100kΩ = ~100kHz, 10kΩ = ~1MHz); no internal pull-up/down. |
| SHDN/UVLO (Pin 12) | Shutdown & UVLO input | 1.22V falling threshold with programmable hysteresis; sub-µA bias above threshold; enables/disables IC. |
| INTVCC (Pin 13) | Internal regulated supply | 7.15V LDO output (±3%); powers gate driver, PWMOUT, and internal logic; bypass with 4.7µF ceramic. |
| VIN (Pin 14) | Main power input | Accepts 6V–100V; local 0.22µF+ ceramic bypass required; powers INTVCC LDO and internal circuits. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors switch current for slope-compensated current-mode control. |
| GATE (Pin 16) | N-MOSFET gate driver | Drives external FET gate between INTVCC and GND; clamped to GND during shutdown/fault/idle. |
| GND (Pin 17) | Power & signal ground | Common reference for all circuits; exposed pad must be soldered to PCB ground plane for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost) without level shifters or isolated sense amplifiers. |
| Improved OPENLED status pin | LT3756-2–specific latched open-LED reporting with re-assertion after overvoltage recovery. |
| AEC-Q100 Grade I qualification | Validated for automotive under-hood operation from –40°C to +125°C junction temperature. |
| Programmable 100kHz–1MHz frequency | Allows optimization of magnetics size, efficiency, and EMI filtering across diverse system requirements. |
| 100mV high-accuracy current sense threshold | Minimizes sense resistor power loss while maintaining ±10mV tolerance over temperature. |
| True-color 3000:1 PWM dimming | Preserves LED chromaticity and eliminates visible flicker across full dimming range. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving multi-string white LED arrays in adaptive front-lighting systems (AFS) with dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current while supporting rapid PWM dimming for matrix beam control. Use Value: Enables 3000:1 dimming without color shift, withstands 100V transients, and meets AEC-Q100 reliability requirements for safety-critical lighting. | Use Scenario: Powering high-lumen LED fixtures in warehouses and manufacturing facilities with 277VAC rectified input. IC Role / Device Role / Timing Role: High-voltage buck-boost LED driver managing variable input from rectified line and delivering stable current to 48V LED loads. Use Value: Supports 6–100V input range to accommodate brownouts and surges; 100V output capability drives long series strings for high-efficiency luminaires. |
| Streetlight Drivers | UV-C Disinfection Systems |
Use Scenario: Outdoor LED streetlights powered from solar-charged batteries or PoE-derived DC sources with wide voltage variation. IC Role / Device Role / Timing Role: Boost-mode LED controller maintaining constant current despite battery discharge from 12V to 36V. Use Value: 100V output headroom ensures reliable operation with aging LEDs; programmable UVLO prevents deep discharge damage to battery banks. | Use Scenario: Driving high-power UVC LEDs (265nm) in portable disinfection wands and surface treatment units requiring precise current control. IC Role / Device Role / Timing Role: Constant-current source with tight 100mV sense threshold and fast transient response to maintain UVC output stability. Use Value: High-side sensing avoids ground-loop interference in sensitive optical systems; OPENLED fault flag enables automatic shutdown upon LED failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756IMSE-2#TRPBF | Same functionality and specs, but in 16-lead MSOP package (4.9mm × 3mm); higher θJA (43°C/W vs 68°C/W). | Preferred where board space allows larger footprint and thermal vias are less accessible. | Select for legacy MSOP-compatible designs or when QFN assembly infrastructure is unavailable. |
| LT3762IUD#TRPBF | Successor device with integrated 3.3A MOSFET driver, higher 150V input rating, and enhanced fault diagnostics-but no OPENLED pin. | Suitable for new designs prioritizing integration and higher voltage margin over discrete FET flexibility. | Choose when replacing aging LT3756 designs and system-level validation supports updated protection logic. |
Compared with LT3756IMSE-2#TRPBF, the LT3756IUD-2#TRPBF offers superior thermal performance in space-constrained layouts due to its smaller QFN footprint and lower θJA; versus LT3762IUD#TRPBF, it retains the dedicated OPENLED status pin critical for fail-safe LED array monitoring in automotive and medical applications.
Availability
LT3756IUD-2#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp drivers, industrial high-bay lighting, streetlight power supplies, UV-C disinfection modules, and battery-powered portable LED systems requiring stable component supply and AEC-Q100 compliance.
Supply support for LT3756IUD-2#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 product line was engineered specifically for high-reliability, high-voltage LED current regulation in demanding environments-including automotive lighting, outdoor signage, and industrial illumination-where wide input range, topology flexibility, and robust fault protection are essential.
FAQ
What is the key functional difference between LT3756IUD-2#TRPBF and LT3756IUD#TRPBF?
The LT3756IUD-2#TRPBF incorporates the improved OPENLED status pin introduced in the LT3756-2 variant, which latches and re-asserts the open-LED fault signal after overvoltage recovery-unlike the base LT3756 (non–2) version that holds OPENLED de-asserted until FB drops below both thresholds. This behavior enhances fault diagnostics in automotive lighting systems where transient overvoltages are common.
Does LT3756IUD-2#TRPBF support constant-voltage regulation in addition to constant-current mode?
Yes, LT3756IUD-2#TRPBF supports both modes. When configured with FB feedback (e.g., via resistive divider from output), it regulates output voltage to 1.25V at the FB pin. Simultaneously, the ISP/ISN current sense loop remains active-so if LED current exceeds the CTRL-set threshold, the controller defaults to constant-current regulation, providing inherent current limiting during CV operation.
What is the recommended minimum capacitor value for the INTVCC pin on LT3756IUD-2#TRPBF?
Analog Devices specifies a minimum 4.7µF X7R/X5R ceramic capacitor rated for ≥10V, placed as close as possible to the INTVCC pin and GND. This value supports typical gate drive currents and ensures stable LDO operation; undersizing risks GATE driver instability or premature INTVCC UVLO triggering during high-frequency switching.
Can LT3756IUD-2#TRPBF drive a buck-boost LED topology, and what design considerations apply?
Yes, LT3756IUD-2#TRPBF explicitly supports buck-boost configurations using high-side current sensing. Critical considerations include ensuring ISP/ISN common-mode voltage stays within 2.9V–100V, selecting appropriate transformer turns ratio and leakage inductance, and verifying that the OPENLED function remains valid under buck-boost output ripple conditions-especially when FB is tied to output for CV mode.
Is LT3756IUD-2#TRPBF pin-compatible with other variants like LT3756EUD-2#TRPBF?
Yes, LT3756IUD-2#TRPBF is pin-compatible with all LT3756-2 variants in the same QFN package (e.g., LT3756EUD-2#TRPBF), differing only in temperature grade (I-grade = –40°C to +125°C; E-grade = 0°C to +125°C). Electrical specifications, pin functions, and layout are identical-making them direct drop-in replacements where extended low-temperature operation is not required.
LT3756IUD-2#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-2#TRPBF FAQ
1.How can I place an order for LT3756IUD-2#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756IUD-2#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-2#TRPBF reliable?
The price and inventory of LT3756IUD-2#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-2#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3756IUD-2#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756IUD-2#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756IUD-2#TRPBF?
LT3756IUD-2#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756IUD-2#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-2#TRPBF?
For technical support, including LT3756IUD-2#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756IUD-2#TRPBF requirements.
6.How does Aetrix verify that LT3756IUD-2#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3756IUD-2#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-2#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3756IUD-2#TRPBF?
All LT3756IUD-2#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756IUD-2#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-2#TRPBF part is unused and in its original packaging.
Return procedure for LT3756IUD-2#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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