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Analog Devices Inc. LT3756EUD-1#PBF
- Part No.:
- LT3756EUD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756EUD-1#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:547
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Product details
Overview
LT3756EUD-1#PBF from Analog Devices is a constant-current, constant-voltage DC/DC LED controller optimized for automotive and industrial high-brightness LED drivers. It operates from 6V to 100V input, supports up to 100V output, delivers true-color PWM dimming up to 3000:1, and drives external N-channel MOSFETs in boost, buck, or buck-boost topologies - enabling 30W white LED headlamp designs with 94% efficiency.
For engineers reviewing the LT3756EUD-1#PBF datasheet, LT3756EUD-1#PBF pinout, LT3756EUD-1#PBF application, or LT3756EUD-1#PBF equivalent, key selection criteria include its 100mV high-side current sense threshold, frequency synchronization capability (LT3756-1 variant), AEC-Q100 qualification, thermally enhanced 3mm × 3mm QFN package, and integrated open-LED protection with programmable undervoltage lockout.
Technical Context
The LT3756EUD-1#PBF implements fixed-frequency current-mode control with internal 7.15V regulated INTVCC supply for gate driving. Its high-side ISP/ISN current sensing architecture enables flexible topology support - including boost, buck, buck-boost, SEPIC, and flyback - without requiring ground-referenced LED strings.
It features dual-loop regulation: the ISP–ISN differential voltage sets LED current via CTRL-adjustable 100mV full-scale threshold, while FB regulates output voltage to 1.25V. Frequency synchronization (via SYNC pin) and PWM-controlled disconnect switching are implemented for precise timing coordination and fault isolation in safety-critical lighting systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range automotive battery (cold-crank to load-dump) and industrial DC bus inputs. |
| Output Voltage Capability | Up to 100V - enables direct drive of long LED strings without intermediate conversion stages. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables accurate, low-loss high-side sensing with standard 0.1Ω shunts. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor; allows optimization of magnetics size vs. efficiency trade-offs. |
| Dimming Ratio | 3000:1 true-color PWM - preserves LED chromaticity across full brightness range for automotive lighting compliance. |
| Package & Thermal Rating | 16-lead 3mm × 3mm QFN, –40°C to +125°C junction - thermally enhanced for under-hood LED driver applications. |
| AEC-Q100 Qualification | Qualified for automotive applications - meets stress test requirements for temperature cycling, HAST, and ESD per Grade 1. |
Pinout & Package
LT3756EUD-1#PBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17) that must be soldered to PCB for thermal and electrical integrity. θJA = 68°C/W, θJC = 4.2°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch; toggles low during FB overvoltage (>VFB + 60mV) to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Regulates output to 1.25V; enables CV mode and open-LED detection (pulls OPENLED when FB < VFB – 50mV). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; bias current ≤25µA; enables short-circuit detection when ISN < 3V. |
| ISP (Pin 4) | Positive current sense input | High-side current sense input; common-mode range up to 100V; bias current varies with CTRL voltage. |
| VC (Pin 5) | Error amplifier output | Integrates error signal for loop stability; high-impedance during PWM low to retain state for next cycle. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0 to 100mV linearly (0–1V), then clamps at full scale (>1.2V). |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%) for CTRL divider or temperature compensation networks; supplies ≤100µA. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; controls oscillator, GATE, and PWMOUT; shutdown IQ < 1µA 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 switching frequency (100kHz–1MHz); no internal pull-up/down - must not float. |
| SHDN/UVLO (Pin 11) | Enable & undervoltage detect | 1.22V falling threshold with programmable hysteresis; sub-µA bias above threshold; enables 2.1µA pull-down below. |
| INTVCC (Pin 12) | Internal LDO output | 7.15V regulated supply (±3%) for gate/PWMOUT drivers; requires 4.7µF local ceramic bypass. |
| VIN (Pin 13) | Main power input | Accepts 6–100V; internally powers INTVCC; requires ≥0.22µF local ceramic bypass near pin. |
| SENSE (Pin 14) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for slope-compensated current-mode control. |
| GATE (Pin 15) | MOSFET gate driver | Drives external N-channel FET between INTVCC and GND; rise/fall time ≤35ns (3.3nF load). |
| GND (Pin 16) | Power & signal ground | Reference for SENSE, ISP/ISN, and VC; exposed pad (Pin 17) is electrically and thermally connected to this node. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost) without grounding LED cathode - critical for isolated or floating-string designs. |
| Frequency synchronization (SYNC) | Allows precise timing alignment with system clocks or other converters to reduce EMI and avoid beat frequencies. |
| Open-LED fault detection | Asserts OPENLED (pin 3 on LT3756/LT3756-2) when FB drops below VFB – 50mV - provides fail-safe status for ASIL-B lighting systems. |
| Programmable soft-start | External capacitor on SS pin prevents inrush current and stabilizes startup in high-power LED arrays. |
| Integrated 7.15V LDO | Powers gate driver and logic independently of VIN fluctuations - ensures robust MOSFET enhancement even during cold-crank events. |
| AEC-Q100 Grade 1 qualification | Validated for automotive under-hood operation (–40°C to +125°C), including HTOL, TC, and ESD testing per JESD47. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current regulation and dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current controller managing individual LED segments via synchronized PWM dimming and real-time current feedback. Use Value: 3000:1 true-color PWM dimming preserves color temperature across intensity levels, meeting UNECE R149 photometric requirements. | Use Scenario: 100W+ high-bay luminaires operating from 48V DC microgrids in warehouses and factories. IC Role / Device Role / Timing Role: Primary DC/DC controller implementing buck-boost topology to maintain regulated LED current despite ±20% input voltage variation. Use Value: 100V output capability enables single-stage drive of 30–40V LED strings, eliminating cascaded converters and improving system efficiency by >3%. |
| UV-C Sterilization Modules | Avionics Exterior Lighting |
Use Scenario: Pulsed UV-C LED arrays for surface disinfection, requiring precise current pulses and thermal derating control. IC Role / Device Role / Timing Role: Current-regulated pulse generator using CTRL-adjusted threshold and PWM-triggered burst mode. Use Value: 100mV ISP–ISN sense threshold enables accurate current control down to 10mA pulses, critical for dose accuracy in medical-grade sterilization. | Use Scenario: DO-160-compliant wingtip and navigation lights with strict EMI and reliability requirements. IC Role / Device Role / Timing Role: AEC-Q100-qualified LED driver providing synchronized dimming and open-circuit fault reporting via OPENLED. Use Value: Frequency synchronization (SYNC pin) eliminates heterodyne noise in sensitive RF bands, satisfying DO-160 Section 20 radiated emissions limits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | No high-side current sense; uses low-side sensing only; lacks SYNC pin; 60V max VIN. | Not suitable for 100V automotive transients or boost-mode LED strings; limited to lower-voltage industrial lighting. | Select only if input stays ≤60V and topology is strictly buck or SEPIC with grounded LED cathode. |
| LM3410XMY/NOPB | Fixed 1.6MHz frequency; no CTRL analog dimming; no open-LED detection; 40V max VIN. | Designed for compact portable LED flashlights; lacks automotive qualification and fault reporting. | Choose only for cost-sensitive, low-power (<5W), non-automotive applications where board space is critical. |
Compared with LTC3783EFE#PBF and LM3410XMY/NOPB, the LT3756EUD-1#PBF uniquely combines 100V operation, high-side sensing, SYNC capability, and AEC-Q100 qualification - making it the only option for robust, scalable, safety-compliant automotive LED drivers requiring topology flexibility and system-level timing coordination.
Availability
LT3756EUD-1#PBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial high-bay luminaires, UV-C sterilization modules, and avionics exterior lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT3756EUD-1#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 (now part of Analog Devices, Inc., a wholly owned subsidiary of Analog Devices, Inc.) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.
The LT3756 family was designed specifically for high-reliability, high-efficiency LED driver applications in automotive, industrial, and medical systems - emphasizing wide input range, topology flexibility, and integrated protection features.
FAQ
What is the key functional difference between LT3756EUD-1#PBF and the base LT3756EUD#PBF?
The LT3756EUD-1#PBF includes the SYNC pin for external oscillator synchronization, replacing the OPENLED function found on the LT3756EUD#PBF and LT3756EUD-2#PBF. This enables precise timing coordination with other system clocks or converters - essential for EMI reduction in multi-rail automotive lighting systems. The LT3756EUD-1#PBF retains all other specifications of the base part, including 100V input/output capability, 100mV current sense threshold, and AEC-Q100 qualification.
Does LT3756EUD-1#PBF support constant-voltage regulation, and how is it configured?
Yes, LT3756EUD-1#PBF supports constant-voltage regulation via the FB pin, which is internally regulated to 1.25V. To configure CV mode, connect FB to the output voltage divider network (e.g., resistive divider from LED string anode to GND). When FB voltage falls below 1.25V – 50mV, the OPENLED pin asserts (if enabled via external circuitry), signaling open-circuit conditions. The IC automatically transitions between CC and CV modes based on load behavior - ensuring safe operation during LED string faults.
What is the minimum recommended value for the RT resistor to achieve 1MHz switching on LT3756EUD-1#PBF?
The LT3756EUD-1#PBF achieves approximately 1MHz switching with an RT resistor of 10kΩ connected from Pin 10 (RT) to GND, per the "Switching Frequency vs RT" curve in the datasheet. At 25°C, RT = 10kΩ yields 1000kHz (typical); values below 10kΩ are not characterized and may cause instability or reduced duty-cycle range. Always verify frequency and loop stability under worst-case temperature and load conditions before finalizing the RT value.
How does the LT3756EUD-1#PBF handle short-circuit conditions on the LED string?
The LT3756EUD-1#PBF detects short-circuits via the ISP–ISN differential when ISN voltage drops below 3V. If ISP exceeds ISN by more than 150mV (typical), the SR latch resets immediately - forcing GATE low and halting switching regardless of PWM or VC state. This protects the external MOSFET and inductor from excessive current. The condition is latched until PWM goes low and high again, ensuring reliable fault hold-off during transient events.
Can LT3756EUD-1#PBF be used in a buck configuration with the LED string connected to VIN instead of GND?
Yes, LT3756EUD-1#PBF supports buck configuration with high-side LED placement - enabled by its high-side current sensing architecture (ISP/ISN inputs). In this arrangement, the LED anode connects to VIN, cathode to the switch node, and current sense resistor is placed between ISP and ISN in series with the LED cathode path. This maintains accurate current regulation without requiring the LED string to be grounded - a key advantage over low-side-sensing controllers.
LT3756EUD-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tube
- 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:
- -
- Current - Output / Channel:
- -
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3756EUD-1#PBF FAQ
1.How can I place an order for LT3756EUD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756EUD-1#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 LT3756EUD-1#PBF reliable?
The price and inventory of LT3756EUD-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3756EUD-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3756EUD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756EUD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756EUD-1#PBF?
LT3756EUD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756EUD-1#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 LT3756EUD-1#PBF?
For technical support, including LT3756EUD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756EUD-1#PBF requirements.
6.How does Aetrix verify that LT3756EUD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756EUD-1#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 LT3756EUD-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3756EUD-1#PBF?
All LT3756EUD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756EUD-1#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 LT3756EUD-1#PBF part is unused and in its original packaging.
Return procedure for LT3756EUD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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