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Analog Devices Inc. LT3756IUD#PBF
- Part No.:
- LT3756IUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756IUD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:138
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Product details
Overview
LT3756IUD#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, senses current on the high side (100mV threshold), and drives external N-channel MOSFETs via a 7.15V regulated gate driver supply - used in white LED headlamp systems requiring robust open-LED protection and thermal resilience.
For engineers reviewing the LT3756IUD#PBF datasheet, LT3756IUD#PBF pinout, LT3756IUD#PBF application, or LT3756IUD#PBF equivalent, key selection considerations include its 100VIN/100VOUT capability, high-side current sensing architecture, AEC-Q100 qualification, adjustable 100kHz–1MHz switching frequency, and dual regulation modes (constant-current and constant-voltage) with integrated open-LED fault signaling.
Technical Context
The LT3756IUD#PBF implements a fixed-frequency, current-mode control architecture with internal slope compensation, enabling stable operation across wide VIN (6V–100V) and VOUT (up to 100V) ranges. Its high-side ISP/ISN current sense interface allows flexible topology support - including boost, buck, buck-boost, SEPIC, and flyback - without ground-referenced LED string constraints.
It integrates dual feedback loops: one for LED current regulation (via ISP/ISN differential voltage referenced to CTRL-adjustable threshold) and another for output voltage regulation (via FB pin referenced to 1.25V). The OPENLED pin provides latched open-circuit detection (−50mV hysteresis relative to FB regulation), while PWMOUT enables active load disconnect during overvoltage events (FB > VFB + 60mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports 12V/24V/48V automotive and industrial rails with 100V transient tolerance. |
| Output Voltage Capability | Up to 100V - enables driving long LED strings in headlamps, signage, and architectural lighting. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side current sensing with minimal power dissipation. |
| Switching Frequency Range | 100kHz to 1MHz - programmable via RT resistor to optimize efficiency, EMI, or magnetic component size. |
| Dimming Ratio | 3000:1 true-color PWM dimming - preserves color consistency across full brightness range in high-end lighting. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade I for under-hood automotive applications. |
| Package Thermal Resistance | θJA = 68°C/W (QFN) - requires exposed pad soldering to PCB ground for reliable thermal management. |
Pinout & Package
LT3756IUD#PBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17), rated for –40°C to +125°C operation. 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 / Overvoltage fault signal | Drives external NMOS disconnect switch; pulled low when FB exceeds VFB + 60mV to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Ground-referenced node for CV regulation or open-LED detection; regulates to 1.25V nominal. |
| ISN (Pin 3) | Negative current sense input | Connects to low side of high-side sense resistor; enables short-circuit detection below 3V common mode. |
| ISP (Pin 4) | Positive current sense input | Connects to high side of sense resistor; bias current varies with CTRL voltage for analog dimming. |
| VC (Pin 5) | Error amplifier output | High-impedance transconductance output; stores demand state during PWM off-time for seamless dimming. |
| CTRL (Pin 6) | Current threshold adjustment | Sets ISP–ISN threshold from 0mV to 100mV linearly (0–1V) then clamps; enables analog dimming and temp compensation. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%) for CTRL divider or external temperature-sensing circuitry; supplies ≤100µA. |
| PWM (Pin 8) | Digital dimming enable | Active-high input; disables oscillator and forces GATE/PWMOUT low when low; internal pull-down. |
| SS (Pin 10) | Soft-start timing | 10µA internal current source charges external capacitor; resets on UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100kΩ yields ~375kHz (per datasheet curve). |
| SHDN/UVLO (Pin 12) | Enable & undervoltage lockout | 1.22V falling threshold with programmable hysteresis; pulls 2.1µA below threshold to set rising edge. |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate driver and logic; requires 4.7µF local ceramic bypass. |
| VIN (Pin 14) | Main power input | Accepts 6–100V; powers INTVCC LDO and internal circuits; bypass with ≥0.22µF ceramic near pin. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current for current-mode control. |
| GATE (Pin 16) | N-MOSFET gate driver | Drives external FET between INTVCC and GND; fast rise/fall (<35ns) into 3300pF load. |
| GND (Pin 17) | Power & signal ground | Exposed thermal pad; connects to negative terminal of SENSE resistor and system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost/SEPIC/flyback) without LED-string grounding constraints. |
| AEC-Q100 Grade I qualification | Validated for automotive under-hood use with guaranteed operation from –40°C to +125°C junction. |
| Programmable open-LED detection | OPENLED pin asserts when FB drops 50mV below 1.25V reference - latched during PWM low for reliable fault reporting. |
| Integrated overvoltage protection | PWMOUT forced low when FB exceeds 1.25V + 60mV - actively disconnects LED load to prevent damage. |
| Adjustable analog dimming via CTRL | Linear 0–1V CTRL input scales current sense threshold from 0mV to 100mV, enabling precise analog brightness control. |
Applications
| Automotive LED Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving multi-string white LEDs in adaptive front-lighting systems (AFS) with dynamic beam shaping and thermal derating. IC Role / Device Role / Timing Role: Constant-current controller managing high-side current sensing, PWM dimming, and open-circuit fault signaling in boost configuration. Use Value: Delivers 94% efficiency at 30W with 3000:1 dimming ratio and AEC-Q100 compliance - meeting OEM headlamp reliability and EMC requirements. | Use Scenario: Powering high-lumen LED arrays in warehouse and factory ceiling fixtures operating from 48V DC distribution rails. IC Role / Device Role / Timing Role: Buck-mode constant-current regulator with programmable UVLO and soft-start for surge-tolerant industrial mains-derived supplies. Use Value: Supports 100V output headroom for long LED strings and withstands 100V transients - reducing need for upstream TVS protection. |
| UV-C Disinfection Systems | Stage & Architectural LED Drivers |
Use Scenario: Driving high-power UVC LEDs (265nm–285nm) requiring precise current regulation and thermal foldback in medical sterilization equipment. IC Role / Device Role / Timing Role: Constant-current source with CTRL-based analog dimming and temperature-compensated current limit via VREF divider. Use Value: Enables accurate current setting down to 100mV sense threshold - minimizing resistive loss and self-heating in high-current UVC modules. | Use Scenario: Controlling RGBW LED pixels in dynamic façade lighting where color fidelity and flicker-free dimming are critical. IC Role / Device Role / Timing Role: Dual-loop controller supporting both constant-current (for LEDs) and constant-voltage (for onboard logic) outputs in SEPIC topology. Use Value: Simultaneous CC/CV regulation avoids separate power rails; 100kHz–1MHz frequency tuning minimizes audible noise in quiet environments. |
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 200kHz–2MHz frequency range; no OPENLED pin; requires external VREF for CTRL scaling. | Lacks integrated open-LED status and has narrower UVLO hysteresis control - less suited for automotive fault-reporting requirements. | Select when higher switching frequencies (>1MHz) and lower quiescent current (<1µA shutdown) are prioritized over fault diagnostics. |
| MAX16834ATL+T | 6V–65V input; 100mV current sense; no high-side sensing - only supports buck/boost with grounded LED cathode. | Cannot implement high-side sensing topologies; lacks AEC-Q100 qualification and 100V transient rating. | Choose for cost-sensitive industrial buck-only designs where 65V max input suffices and ground-referenced LED strings are acceptable. |
Compared with LTC3783EFE#PBF and MAX16834ATL+T, the LT3756IUD#PBF uniquely combines 100VIN/100VOUT capability, AEC-Q100 Grade I qualification, high-side current sensing, and integrated OPENLED/PWMOUT fault signaling - making it the only option among the three qualified for demanding automotive headlamp and industrial high-voltage LED applications.
Availability
LT3756IUD#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, and UV-C disinfection systems requiring stable component supply, AEC-Q100 compliance, and high-voltage robustness.
Supply support for LT3756IUD#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 product line was engineered specifically for high-reliability, high-voltage LED driver applications - emphasizing AEC-Q100 qualification, wide input/output voltage operation, and integrated fault protection for automotive and industrial lighting.
FAQ
What is the maximum input voltage rating for the LT3756IUD#PBF?
The LT3756IUD#PBF has an absolute maximum input voltage rating of 100V on the VIN pin, and it operates continuously from 6V to 100V. Its design accommodates 100V transients - critical for automotive 12V/24V systems with load-dump spikes. This rating is confirmed in the Absolute Maximum Ratings table and supported by typical application schematics showing 8V–60V input with 100V transient tolerance.
Does the LT3756IUD#PBF support both constant-current and constant-voltage regulation?
Yes, the LT3756IUD#PBF supports dual regulation modes. Constant-current regulation is achieved via high-side ISP/ISN sensing with CTRL-adjustable threshold; constant-voltage regulation uses the FB pin referenced to 1.25V. Both loops operate simultaneously - the IC ensures neither exceeds its limit, enabling safe operation in LED drivers with auxiliary CV loads or overvoltage protection.
How does the OPENLED pin function on the LT3756IUD#PBF?
The OPENLED pin on the LT3756IUD#PBF is an open-collector output that asserts (pulls low) when the FB voltage falls 50mV below its 1.25V regulation threshold - indicating an open LED string. It remains latched during PWM low periods and updates when PWM goes high. This behavior is specific to LT3756 and LT3756-2 variants; the LT3756-1 replaces OPENLED with SYNC functionality.
What package type and thermal specifications apply to the LT3756IUD#PBF?
The LT3756IUD#PBF uses a 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17). Its thermal resistance is θJA = 68°C/W and θJC = 4.2°C/W. The exposed pad must be soldered to a PCB ground plane for effective heat dissipation - essential for maintaining operation within the –40°C to +125°C junction temperature range.
Can the LT3756IUD#PBF drive LED strings in buck configuration with high-side current sensing?
Yes, the LT3756IUD#PBF supports buck-mode operation with high-side current sensing - a key differentiator from conventional buck controllers. By sensing current on the high side (via ISP/ISN), it eliminates the need to route high-current return paths through ground, enabling floating LED strings and simplifying layout in high-noise or multi-string systems.
LT3756IUD#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:
- 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#PBF FAQ
1.How can I place an order for LT3756IUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756IUD#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 LT3756IUD#PBF reliable?
The price and inventory of LT3756IUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3756IUD#PBF is usually 5 days.
3.What payment methods are accepted for LT3756IUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756IUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756IUD#PBF?
LT3756IUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756IUD#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 LT3756IUD#PBF?
For technical support, including LT3756IUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756IUD#PBF requirements.
6.How does Aetrix verify that LT3756IUD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756IUD#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 LT3756IUD#PBF meets industry standards.
7.What is the process for return or replacement of LT3756IUD#PBF?
All LT3756IUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756IUD#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 LT3756IUD#PBF part is unused and in its original packaging.
Return procedure for LT3756IUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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