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Analog Devices Inc. LT3756EUD#PBF
- Part No.:
- LT3756EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756EUD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,461
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Product details
Overview
LT3756EUD#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, and drives external N-channel MOSFETs in boost, buck, or buck-boost topologies - enabling white LED headlamp drivers and high-power signage systems.
For engineers reviewing the LT3756EUD#PBF datasheet, LT3756EUD#PBF pinout, LT3756EUD#PBF application, or LT3756EUD#PBF equivalent, key selection criteria include high-side current sensing (100mV threshold), adjustable switching frequency (100kHz–1MHz), AEC-Q100 qualification, open LED protection via FB pin, and thermally enhanced 3mm × 3mm QFN package with exposed GND pad.
Technical Context
The LT3756EUD#PBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator, enabling stable operation across wide VIN (6V–100V) and VOUT (up to 100V) ranges. Its ground-referenced FB pin supports dual regulation modes: constant-current via ISP/ISN differential sensing and constant-voltage via FB feedback - both independently configurable.
High-side current sensing architecture allows topology flexibility (boost/buck/buck-boost/SEPIC/flyback), while PWM and CTRL pins provide true-color PWM dimming (3000:1) and analog dimming. The device integrates open LED detection (FB < VFB − 50mV), overvoltage protection (FB > VFB + 60mV), and short-circuit protection (ISP−ISN > 150mV at VISN < 3V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports 12V/24V/48V industrial rails and automotive transients up to 100V. |
| Output Voltage Capability | Up to 100V - enables driving long LED strings (e.g., 30+ white LEDs @ 3.2V each) without cascading converters. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side sensing with standard 0.1Ω shunts. |
| Switching Frequency Range | 100kHz to 1MHz - programmable via RT resistor to optimize efficiency, EMI, or inductor size. |
| Dimming Ratio | 3000:1 true-color PWM - preserves color fidelity in architectural and automotive lighting applications. |
| Operating Junction Temp | –40°C to +125°C - qualified for under-hood automotive and industrial ambient environments. |
| Package Thermal Resistance | θJA = 68°C/W - requires PCB thermal pad connection for sustained 30W+ operation. |
Pinout & Package
LT3756EUD#PBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17), requiring soldering 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 / Overvoltage fault signal | Drives LED disconnect FET; pulled low if FB exceeds VFB + 60mV to prevent LED overcurrent. |
| FB (Pin 2) | Voltage feedback / Open LED detection input | Regulates to 1.25V nominal; asserts OPENLED when FB < VFB − 50mV (LT3756/LT3756-2 only). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; bias current ≤25µA; enables short-circuit detection below 3V common mode. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high side; bias current varies with CTRL voltage; used with ISN for 100mV threshold. |
| VC (Pin 5) | Error amplifier output | Integrates ISP–ISN vs CTRL error; high-impedance during PWM low to retain state for next cycle. |
| CTRL (Pin 6) | Current threshold adjustment | Sets ISP–ISN threshold from 0–100mV linearly (0–1V) or fixed (≥1.2V); enables analog dimming and temp compensation. |
| VREF (Pin 7) | 2.00V reference output | Stable 2V source (±2%); supplies up to 100µA for CTRL divider or temperature-sensing networks. |
| PWM (Pin 8) | Digital dimming enable | Active-high; disables switching and idles oscillator when low; internal pull-down. |
| SS (Pin 9) | Soft-start timing | 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 → ~100kHz; 10kΩ → ~1MHz). |
| SHDN/UVLO (Pin 11) | Enable / Input undervoltage lockout | 1.22V falling threshold with programmable hysteresis; sub-µA shutdown IQ when <0.4V. |
| INTVCC (Pin 12) | Internal 7.15V LDO supply | Regulated output powers gate driver and logic; requires 4.7µF local ceramic bypass. |
| VIN (Pin 13) | Main power input | Accepts 6–100V; must be bypassed with ≥0.22µF ceramic capacitor near pin. |
| SENSE (Pin 14) | Low-side switch current sense | Kelvin-connected to source of external NMOS; monitors peak switch current for current-mode control. |
| GATE (Pin 15) | NMOS gate driver output | Swings between INTVCC and GND; drives external FET gate; forced low during fault/shutdown. |
| GND (Pin 16) | Power and signal ground | Reference for SENSE, ISN, and exposed thermal pad; must be solidly connected to PCB ground plane. |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Integral GND connection; mandatory soldering to PCB thermal plane for thermal performance and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost/SEPIC/flyback) without ground-loop interference. |
| AEC-Q100 qualification | Validated for automotive applications including headlamps, interior lighting, and ADAS displays. |
| Open LED status reporting | OPENLED pin asserts when FB drops below VFB − 50mV, providing real-time fault indication without external circuitry. |
| Programmable soft-start | External capacitor on SS pin controls startup inrush current and prevents output overshoot during power-up. |
| Integrated 7.15V LDO | Powers gate driver and logic directly from VIN, eliminating need for external bias supply in most designs. |
| Low shutdown current | <1µA IQ when SHDN/UVLO < 0.4V - extends battery life in always-on vehicle systems. |
Applications
| Automotive Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
|
Use Scenario: Driving 30W white LED arrays in vehicle forward lighting with transient immunity to 100V load-dump events. IC Role / Device Role / Timing Role: Constant-current controller managing boost converter with high-side current sensing and PWM dimming synchronization. Use Value: Enables 3000:1 true-color dimming while maintaining AEC-Q100 compliance and open-circuit LED fault detection. |
Use Scenario: Powering multi-string 100V LED fixtures in warehouse ceilings using 48V DC distribution bus. IC Role / Device Role / Timing Role: Buck-mode LED controller regulating string current with programmable frequency to minimize EMI in shared power infrastructure. Use Value: Delivers 94% efficiency at full load with integrated 100mV current sense and thermal shutdown at 125°C junction. |
| Architectural Signage | Battery-Powered Emergency Lighting |
|
Use Scenario: Controlling RGBW LED modules in outdoor digital billboards exposed to wide temperature (-40°C to +85°C ambient). IC Role / Device Role / Timing Role: Constant-current source supporting SEPIC topology for wide-input-range operation with analog + PWM dimming. Use Value: Maintains color consistency across dimming range via true-color PWM and compensates for LED forward-voltage drift with CTRL-based current scaling. |
Use Scenario: Driving emergency exit signs from 12V sealed lead-acid or LiFePO₄ batteries with low-quiescent operation. IC Role / Device Role / Timing Role: Boost LED driver with <1µA shutdown current and programmable UVLO to maximize battery runtime. Use Value: Extends backup runtime by 3× versus legacy controllers through sub-µA quiescent draw and efficient 100kHz–1MHz switching. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756EUD-1#PBF | Includes SYNC pin for external clock synchronization; lacks OPENLED pin functionality. | Preferred where system-level clock alignment is required (e.g., multi-channel synchronized lighting). | Select when deterministic phase relationship with master clock is needed; not drop-in compatible due to pin function swap (SYNC replaces OPENLED). |
| LT3756EUD-2#PBF | Enhanced OPENLED latching behavior: reasserts after FB falls below overvoltage threshold but remains above open-LED threshold. | Better suited for intermittent fault conditions where transient overvoltage should not mask persistent open-LED faults. | Choose for robust fault diagnostics in safety-critical lighting; identical pinout and electrical specs except OPENLED logic timing. |
Compared with LT3756EUD#PBF, the -1 variant trades open-fault reporting for clock sync capability, while the -2 variant improves fault recovery behavior without changing footprint or basic regulation - making the base EUD#PBF optimal for cost-sensitive, single-channel automotive and industrial LED drivers requiring reliable open-LED detection.
Availability
LT3756EUD#PBF is available at Aetrix Electronics and suitable for automotive headlamp drivers, industrial high-bay lighting, and battery-powered emergency signage requiring stable component supply, AEC-Q100 compliance, and high-voltage LED control.
Supply support for LT3756EUD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3756 product line was engineered specifically for high-reliability, high-voltage LED current regulation in harsh environments - emphasizing wide input range, topology flexibility, and integrated protection features for automotive and industrial lighting.
FAQ
What is the maximum input voltage rating for the LT3756EUD#PBF?
The LT3756EUD#PBF has an absolute maximum input voltage rating of 100V on the VIN pin, and it operates continuously from 6V to 100V. This makes the LT3756EUD#PBF suitable for automotive applications with load-dump transients and industrial 48V/60V DC systems. Exceeding 100V may cause permanent damage per Absolute Maximum Ratings.
Does the LT3756EUD#PBF support both constant-current and constant-voltage regulation?
Yes, the LT3756EUD#PBF supports dual regulation modes: constant-current via high-side ISP/ISN sensing and constant-voltage via the FB pin. When FB is used, the internal transconductance amplifier regulates it to 1.25V nominal. The LT3756EUD#PBF automatically prioritizes the active loop - current regulation dominates unless FB is driven above its threshold, enabling hybrid LED + battery-charging applications.
How does the OPENLED function work on the LT3756EUD#PBF?
The OPENLED pin on the LT3756EUD#PBF is an open-collector output that pulls down when the FB voltage falls below VFB − 50mV (typically 1.20V), indicating an open LED string. It requires an external pull-up current <1mA. During PWM low periods, the state is latched; it updates only when PWM goes high again. This behavior is confirmed for LT3756EUD#PBF (non–1/non–2 variants) per Pin Functions section.
What package type and thermal requirements apply to the LT3756EUD#PBF?
The LT3756EUD#PBF uses a 16-lead 3mm × 3mm plastic QFN package with exposed GND pad (Pin 17). That pad must be soldered to a PCB thermal plane to achieve θJA = 68°C/W. Without proper thermal pad connection, junction temperature rise will exceed safe limits under 30W operation. The device is rated for –40°C to +125°C junction temperature.
Can the LT3756EUD#PBF drive a buck-boost LED topology?
Yes, the LT3756EUD#PBF explicitly supports buck-boost, boost, buck, SEPIC, and flyback topologies due to its high-side current sensing architecture and flexible feedback structure. Unlike traditional controllers tied to ground-referenced sensing, the LT3756EUD#PBF's ISP/ISN inputs allow the LED string to float - enabling direct implementation of non-inverting buck-boost configurations for wide-output-range LED drivers.
LT3756EUD#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#PBF FAQ
1.How can I place an order for LT3756EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756EUD#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#PBF reliable?
The price and inventory of LT3756EUD#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#PBF is usually 5 days.
3.What payment methods are accepted for LT3756EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756EUD#PBF?
LT3756EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756EUD#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#PBF?
For technical support, including LT3756EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756EUD#PBF requirements.
6.How does Aetrix verify that LT3756EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756EUD#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#PBF meets industry standards.
7.What is the process for return or replacement of LT3756EUD#PBF?
All LT3756EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756EUD#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#PBF part is unused and in its original packaging.
Return procedure for LT3756EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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