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Analog Devices Inc. LT3756EUD-2#PBF
- Part No.:
- LT3756EUD-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756EUD-2#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3756EUD-2#PBF from Analog Devices is a high-voltage constant-current LED controller IC designed for automotive and industrial LED drivers. It operates from 6V to 100V input, delivers up to 100V output, supports 3000:1 PWM dimming, features high-side current sensing, and drives external N-channel MOSFETs in boost, buck, or buck-boost topologies - used in white LED headlamp systems requiring robust open-LED protection and thermal resilience.
For engineers reviewing the LT3756EUD-2#PBF datasheet, LT3756EUD-2#PBF pinout, LT3756EUD-2#PBF application, or LT3756EUD-2#PBF equivalent, key selection criteria include its 100mV high-side current sense threshold, programmable 100kHz–1MHz switching frequency, AEC-Q100 qualification, integrated 7.15V INTVCC regulator, and improved OPENLED status reporting specific to the -2 variant.
Technical Context
The LT3756EUD-2#PBF implements fixed-frequency current-mode control with dual-loop regulation: one loop uses ISP/ISN differential voltage (target 100mV) for constant-current LED drive, the other uses FB (regulated to 1.25V) for constant-voltage or open-LED fault detection. Its architecture includes slope compensation, soft-start via SS pin, and internal transconductance error amplifier (VC) with high-impedance hold during PWM off-time.
Unlike the LT3756 and LT3756-1, the LT3756EUD-2#PBF replaces SYNC functionality with enhanced OPENLED behavior: it re-asserts the open-LED flag when FB falls below overvoltage threshold but remains above open-LED threshold, enabling more reliable fault latching in transient conditions - critical for automotive lighting safety compliance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range automotive battery inputs including cold-crank (6V) and load-dump transients (100V). |
| Output Voltage Capability | Up to 100V - enables driving long LED strings in high-brightness headlamps without cascading converters. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets precise LED current with minimal power loss in sense resistor. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT pin resistor to optimize EMI, efficiency, or inductor size. |
| INTVCC Regulator | 7.15V ±0.15V - powers gate driver and internal logic; includes UVLO (4.1V) and 17mA current limit. |
| Open LED Detection | FB < 1.20V (–4% of 1.25V) - triggers OPENLED pull-down; LT3756EUD-2#PBF re-asserts after overvoltage recovery. |
| Dimming Support | 3000:1 true-color PWM dimming + analog dimming via CTRL pin - preserves color fidelity across full brightness range. |
Pinout & Package
LT3756EUD-2#PBF is housed in a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17), rated for –40°C to +125°C junction temperature. The package supports high-power density layouts and requires soldering the exposed pad to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives external NMOS disconnect switch; toggles low if FB exceeds 1.25V + 60mV for overvoltage protection. |
| FB (Pin 2) | Voltage feedback input | Regulated to 1.25V nominal; enables CV mode and open-LED detection (LT3756EUD-2#PBF asserts OPENLED when FB < 1.20V). |
| 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; combined bias with ISN <0.1µA in standby. |
| VC (Pin 5) | Error amplifier output | Transconductance output (480µS); stores demand state during PWM off; requires RC compensation to GND. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0mV to 100mV linearly (0–1V) then clamps; enables analog dimming and thermal derating. |
| VREF (Pin 7) | 2.00V reference output | Stable 2V source (±20mV); supplies ≤100µA; used for CTRL biasing or temperature compensation networks. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; disables switching and idles VC when low; controls 3000:1 PWM dimming. |
| OPENLED (Pin 9) | Open-LED status output | Open-collector pull-down; asserted when FB < 1.20V (LT3756EUD-2#PBF only); requires <1mA external pull-up. |
| SS (Pin 10) | Soft-start control | 10µA internal pull-up to 2.5V rail; sets startup ramp time with external capacitor; reset by UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency (100kHz–1MHz); 100kΩ yields ~100kHz, 10kΩ yields ~1MHz. |
| SHDN/UVLO (Pin 12) | Shutdown & input monitoring | 1.22V falling threshold with programmable hysteresis; sub-µA bias above threshold; pulls down 2.1µA below threshold. |
| INTVCC (Pin 13) | Internal regulated supply | 7.15V LDO output; powers gate driver and logic; requires 4.7µF ceramic bypass close to pin. |
| VIN (Pin 14) | Main input supply | Accepts 6–100V; must be bypassed with ≥0.22µF ceramic capacitor near pin; powers INTVCC LDO. |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for peak-current-mode control; clamp at 108mV. |
| GATE (Pin 16) | NMOS gate driver | Drives external N-channel MOSFET gate between INTVCC and GND; 35ns rise/fall into 3.3nF load. |
| GND (Pin 17) | Power & signal ground | Exposed thermal pad; connects to PCB ground plane; serves as current sense return for SENSE and ISN paths. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without ground-referenced LED string constraints. |
| AEC-Q100 qualification | Validated for automotive applications across –40°C to +125°C; supports headlamp, DRL, and interior lighting systems. |
| Improved OPENLED status logic | LT3756EUD-2#PBF re-latches OPENLED after overvoltage recovery, improving fault diagnosis reliability in noisy automotive environments. |
| Programmable undervoltage lockout | Accurate 1.22V shutdown threshold with user-defined hysteresis via resistor divider - ensures stable start-up under battery sag. |
| 100mV current sense threshold | Minimizes I²R losses in sense resistor while maintaining precision; supports accurate LED current regulation across temperature. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving 30W white LED arrays in adaptive front-lighting systems (AFS) with dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current controller managing boost converter stage; regulates LED current via high-side ISP/ISN sensing and provides PWM dimming synchronization. Use Value: Enables 3000:1 true-color dimming without color shift, meets ECE R149 photometric requirements, and sustains operation during 100V load-dump transients. | Use Scenario: Powering multi-string 100V LED fixtures in warehouse ceilings with >50,000-hour lifetime requirements. IC Role / Device Role / Timing Role: Primary LED current controller in buck-boost configuration; handles wide input variation (12–56V DC) from PoE++ or industrial SMPS. Use Value: Delivers stable current despite input ripple; open-LED detection prevents thermal runaway; AEC-Q100 grade ensures field reliability beyond standard industrial temp range. |
| UV-C Sterilization Modules | Battery-Powered Emergency Lighting |
Use Scenario: Driving high-voltage UV-C LED strings (36–80V) in portable disinfection wands requiring precise irradiance control. IC Role / Device Role / Timing Role: Constant-current source with analog dimming (CTRL pin) for dose calibration; uses high-side sensing to isolate LED cathode from system ground. Use Value: 100mV sense threshold minimizes power loss in compact designs; 100V capability supports series-connected UV-C LEDs; thermal shutdown protects against LED overheating. | Use Scenario: LED driver in emergency exit signs powered by sealed lead-acid or LiFePO₄ batteries (10–30V range) with 90+ minute runtime. IC Role / Device Role / Timing Role: Buck-mode LED controller with ultra-low shutdown current (<1µA) and programmable soft-start to prevent inrush during battery recovery. Use Value: Extends battery life via <1µA quiescent current in shutdown; 6V minimum VIN ensures operation down to deeply discharged batteries; OPENLED flag triggers backup alert. |
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 | Fixed 500kHz frequency; no high-side current sense; uses VCS low-side sensing; lacks OPENLED pin and AEC-Q100 rating. | Targeted at lower-voltage (<60V) industrial LED drivers where topology flexibility and automotive qualification are not required. | Select LTC3783EFE#PBF only for cost-sensitive, non-automotive designs with simpler buck-only topology and no open-LED reporting need. |
| LM3410XSDX/NOPB | Integrated 1.5A MOSFET; max 42V input; no high-side sensing; no programmable frequency; no OPENLED or CTRL analog dimming. | Designed for compact, low-power (<10W) LED modules where integration reduces BOM count but sacrifices voltage headroom and diagnostics. | Choose LM3410XSDX/NOPB for space-constrained, low-power indicator lighting - not suitable for LT3756EUD-2#PBF's 100V/30W automotive use case. |
Compared with LTC3783EFE#PBF and LM3410XSDX/NOPB, the LT3756EUD-2#PBF uniquely combines 100V operation, high-side current sensing, AEC-Q100 qualification, and intelligent OPENLED latching - making it irreplaceable for high-reliability, high-voltage automotive LED systems requiring fault-aware control.
Availability
LT3756EUD-2#PBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial high-bay lighting, UV-C sterilization modules, and battery-powered emergency lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT3756EUD-2#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3756 family is part of Analog Devices' Power by Linear™ portfolio, engineered specifically for high-voltage, high-reliability LED driver applications demanding precise current regulation, robust fault protection, and automotive-grade qualification.
FAQ
What is the key functional difference between LT3756EUD-2#PBF and LT3756EUD#PBF?
The LT3756EUD-2#PBF features an improved OPENLED status pin behavior: it re-asserts the open-LED flag after FB falls below the overvoltage threshold (1.31V) but remains above the open-LED threshold (1.20V), whereas the base LT3756EUD#PBF requires FB to drop below both thresholds before re-asserting. This makes LT3756EUD-2#PBF more robust for diagnosing intermittent open-LED faults in automotive environments where voltage transients are common.
Does LT3756EUD-2#PBF support buck-boost topology, and how is it implemented?
Yes, LT3756EUD-2#PBF supports buck-boost topology using high-side current sensing at ISP/ISN, which decouples the LED string from ground and allows the converter to operate regardless of whether output voltage is higher or lower than input. Implementation requires proper transformer or coupled inductor design, with the LT3756EUD-2#PBF regulating LED current via the ISP–ISN differential voltage while maintaining stable current-mode control across duty cycles.
What is the maximum allowable voltage on the ISP and ISN pins of LT3756EUD-2#PBF?
The absolute maximum rating for ISP and ISN pins of LT3756EUD-2#PBF is 100V, as specified in the Absolute Maximum Ratings table. This enables direct connection to high-voltage LED strings in boost configurations without level-shifting circuitry - a critical enabler for 100V-output LED drivers used in premium automotive headlamps.
How does the CTRL pin on LT3756EUD-2#PBF enable analog dimming and thermal derating?
The CTRL pin on LT3756EUD-2#PBF linearly adjusts the ISP–ISN current sense threshold from 0mV to 100mV as VCTRL rises from 0V to 1V, enabling smooth analog dimming. Above 1.2V, the threshold clamps at 100mV. For thermal derating, a thermistor-based voltage divider can feed a decreasing VCTRL as temperature rises, proportionally reducing LED current - directly implemented in LT3756EUD-2#PBF without external op-amps.
Is LT3756EUD-2#PBF pin-compatible with LT3756EUD-1#PBF, and what changes are needed on the PCB?
No, LT3756EUD-2#PBF is not pin-compatible with LT3756EUD-1#PBF: Pin 9 is OPENLED on LT3756EUD-2#PBF but SYNC on LT3756EUD-1#PBF. To migrate, remove the SYNC pull-down resistor and external clock source, connect Pin 9 to a 10kΩ pull-up for OPENLED reporting, and update firmware to monitor OPENLED instead of synchronizing to external clock - no layout change is needed beyond this single net reconfiguration.
LT3756EUD-2#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-2#PBF FAQ
1.How can I place an order for LT3756EUD-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756EUD-2#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-2#PBF reliable?
The price and inventory of LT3756EUD-2#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-2#PBF is usually 5 days.
3.What payment methods are accepted for LT3756EUD-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756EUD-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756EUD-2#PBF?
LT3756EUD-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756EUD-2#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-2#PBF?
For technical support, including LT3756EUD-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756EUD-2#PBF requirements.
6.How does Aetrix verify that LT3756EUD-2#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756EUD-2#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-2#PBF meets industry standards.
7.What is the process for return or replacement of LT3756EUD-2#PBF?
All LT3756EUD-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756EUD-2#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-2#PBF part is unused and in its original packaging.
Return procedure for LT3756EUD-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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