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Analog Devices Inc. LT3756IUD-2#PBF
- Part No.:
- LT3756IUD-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756IUD-2#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,712
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Product details
Overview
LT3756IUD-2#PBF from Analog Devices is a high-voltage constant-current LED controller designed for automotive and industrial lighting systems. 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 - enabling 94% efficient 30W white LED headlamp drivers.
For engineers reviewing the LT3756IUD-2#PBF datasheet, LT3756IUD-2#PBF pinout, LT3756IUD-2#PBF application, or LT3756IUD-2#PBF 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 thermal shutdown at 165°C - all critical for robust high-power LED driver design.
Technical Context
The LT3756IUD-2#PBF implements fixed-frequency current-mode control with internal 7.15V regulated INTVCC supply for gate driving. Its dual-loop architecture simultaneously regulates LED current via ISP/ISN differential sensing (100mV full-scale) and output voltage via FB (1.25V reference), with priority logic preventing overvoltage during open-circuit faults.
It integrates dedicated protection circuitry: OPENLED asserts when FB falls 50mV below regulation (indicating open LED), while PWMOUT forces low if FB exceeds regulation by 60mV (overvoltage disconnect). The LT3756-2 variant uniquely reasserts OPENLED after overvoltage recovery - distinguishing it from LT3756 and LT3756-1.
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 driving long LED strings in architectural, streetlight, and headlamp applications. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side 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 size for specific layout constraints. |
| Dimming Ratio | 3000:1 true-color PWM dimming - preserves LED chromaticity across full brightness range for automotive and display lighting. |
| Thermal Protection | 165°C junction shutdown - prevents thermal runaway during overload or poor heatsinking in enclosed fixtures. |
| Package & Temp Grade | 16-lead 3mm × 3mm QFN, –40°C to +125°C - thermally enhanced for high-power density PCB layouts in automotive under-hood environments. |
Pinout & Package
LT3756IUD-2#PBF uses a 16-lead (3mm × 3mm) plastic QFN package with exposed thermal pad (Pin 17 = GND). The package provides θJA = 68°C/W and θJC = 4.2°C/W for effective thermal management in high-current LED driver designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output / Overvoltage fault signal | Drives external NMOS disconnect switch; forced low when FB > VFB + 60mV to isolate LED load during overvoltage events. |
| FB (Pin 2) | Voltage feedback / Open LED detection input | Regulates output voltage to 1.25V; triggers OPENLED pull-down when FB < VFB – 50mV (open LED condition). |
| 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 high side; combined ISP/ISN bias <55µA; used with ISN for 100mV threshold sensing. |
| VC (Pin 5) | Error amplifier output | Integrates current/voltage loop error; high-impedance during PWM low to retain state for seamless dimming transitions. |
| CTRL (Pin 6) | Current threshold adjustment | Sets ISP–ISN threshold from 0mV to 100mV via 0–1.1V input; enables analog dimming and temperature compensation. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%) for CTRL divider or external temp-sensing circuits; supplies up to 100µA. |
| PWM (Pin 8) | Digital dimming enable | Active-high control: low disables switching, idles oscillator, and isolates VC; internal pull-down. |
| OPENLED (Pin 9) | Open LED status indicator | Open-collector output; pulls down when FB < VFB – 50mV; latched during PWM low; reasserts post-overvoltage on LT3756-2. |
| SS (Pin 10) | Soft-start timing | 10µA pull-up to 2.5V rail; external capacitor sets startup ramp time; reset by UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency (100kHz–1MHz); determines minimum off-time (170ns) and slope compensation. |
| SHDN/UVLO (Pin 12) | Enable & undervoltage lockout | 1.22V falling threshold with 20mV hysteresis; sub-µA bias above threshold; enables 2.1µA pull-down for programmable hysteresis. |
| INTVCC (Pin 13) | Internal 7.15V regulator output | Powers gate driver and logic; requires 4.7µF local ceramic bypass; current-limited to 17mA (typ) to protect LDO. |
| VIN (Pin 14) | Main power input | Accepts 6–100V; must be bypassed with ≥0.22µF ceramic cap near pin; powers INTVCC LDO and internal circuits. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current; clamped at 108mV to prevent overcurrent. |
| GATE (Pin 16) | N-MOSFET gate driver | Drives external FET between INTVCC and GND; rise/fall time <35ns (CL = 3300pF); disabled during shutdown/fault. |
| 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 |
|---|---|
| AEC-Q100 qualified | Rated for automotive applications (-40°C to +125°C junction), supporting headlamp, DRL, and interior lighting with validated reliability. |
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without compromising ground-referenced LED cathode/anode configuration. |
| Programmable open LED response | LT3756-2 variant reasserts OPENLED after overvoltage clears - enabling accurate fault reporting in transient-heavy automotive environments. |
| Integrated 7.15V INTVCC regulator | Eliminates need for external bias supply; powers gate driver and logic; includes UVLO (4.1V) and current limit (17mA) for robust FET drive. |
| True-color 3000:1 PWM dimming | Maintains consistent LED color point across full dimming range - essential for automotive adaptive lighting and human-centric lighting systems. |
| 100mV current sense threshold | Reduces I²R losses in sense resistor by >50% vs. conventional 200mV controllers, improving thermal performance and efficiency in high-current designs. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: 30W white LED headlamp driver operating from 8–60V automotive battery with 100V transient tolerance. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current via high-side ISP/ISN sensing; manages boost topology with external N-MOSFET and 22µH inductor. Use Value: Delivers 94% efficiency and 3000:1 dimming while meeting AEC-Q100 requirements for vibration, temperature, and EMI resilience. | Use Scenario: 100V-output, multi-string LED driver for warehouse high-bay fixtures powered from 48V DC microgrid. IC Role / Device Role / Timing Role: Buck-boost controller maintaining constant current across varying line and load conditions; uses RT pin to set 375kHz switching for compact magnetics. Use Value: Enables single-controller solution for 100V LED strings without intermediate DC-DC stages, reducing BOM cost and footprint. |
| Streetlight Drivers | UV-C Disinfection Systems |
Use Scenario: Outdoor LED streetlight with surge-rated 100V input, thermal foldback, and remote fault signaling. IC Role / Device Role / Timing Role: Constant-current source with OPENLED reporting open-circuit faults to central management system; uses CTRL pin for temperature-compensated current derating. Use Value: Provides reliable long-life operation in unattended outdoor environments with real-time fault diagnostics and thermal protection. | Use Scenario: Pulsed UV-C LED driver requiring precise current control and fast overvoltage protection to safeguard expensive emitters. IC Role / Device Role / Timing Role: Fast-response current controller using PWMOUT to disconnect LEDs within nanoseconds if FB exceeds safe voltage threshold. Use Value: Prevents catastrophic UV-C LED failure during transient overvoltage events, extending emitter lifetime and ensuring consistent germicidal output. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EMSE#PBF | 4-switch synchronous buck-boost controller; no integrated high-side current sense; requires external op-amp for LED current regulation. | Designed for wide-input DC-DC conversion, not optimized for LED-specific protections (OPENLED, PWMOUT disconnect, dimming interface). | Select when bidirectional power flow or higher efficiency at light loads is required; not drop-in for LED current regulation. |
| LM3410XSDX/NOPB | 65V max input; 1.6MHz fixed frequency; no high-side sensing; only 1000:1 PWM dimming; no OPENLED or overvoltage disconnect. | Targeted at low-power portable LED apps (e.g., flashlights); lacks AEC-Q100 rating and automotive-grade thermal/EMI robustness. | Choose for cost-sensitive, low-power (<5W) consumer lighting where automotive qualification and 100V operation are unnecessary. |
Compared with LTC3789EMSE#PBF and LM3410XSDX/NOPB, the LT3756IUD-2#PBF delivers superior LED-specific functionality - including integrated high-side current sensing, AEC-Q100 qualification, 3000:1 dimming, and dual-fault protection (OPENLED + PWMOUT disconnect) - making it the optimal choice for demanding high-power automotive and industrial LED drivers.
Availability
LT3756IUD-2#PBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial high-bay lighting, streetlight drivers, and UV-C disinfection equipment requiring stable component supply, AEC-Q100 compliance, and high-voltage LED control capability.
Supply support for LT3756IUD-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 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 driver applications - emphasizing robust fault protection, wide input/output ranges, and automotive-grade thermal and EMI performance.
FAQ
What distinguishes LT3756IUD-2#PBF from LT3756IUD#PBF and LT3756IUD-1#PBF?
The LT3756IUD-2#PBF includes an improved OPENLED status pin that reasserts after overvoltage conditions clear - unlike the base LT3756IUD#PBF. The LT3756IUD-1#PBF replaces OPENLED with SYNC for oscillator synchronization. All share identical pinout, package, and core LED control functionality, but differ in fault reporting and clocking features.
Does LT3756IUD-2#PBF support both constant-current and constant-voltage regulation?
Yes, LT3756IUD-2#PBF supports dual-loop regulation: constant-current via ISP/ISN differential sensing (100mV threshold) and constant-voltage via FB pin (1.25V reference). The IC prioritizes current regulation during normal operation but automatically engages voltage regulation and OPENLED reporting during open-LED faults.
What is the purpose of the CTRL pin on LT3756IUD-2#PBF?
The CTRL pin on LT3756IUD-2#PBF adjusts the ISP–ISN current sense threshold from 0mV to 100mV linearly (0–1.1V input), enabling analog dimming, temperature-based current derating, or closed-loop feedback from external sensors - without requiring additional DACs or op-amps.
Can LT3756IUD-2#PBF drive MOSFETs in buck-boost topology?
Yes, LT3756IUD-2#PBF explicitly supports buck-boost, boost, buck, SEPIC, and flyback topologies due to its high-side current sensing architecture. This flexibility allows designers to select the optimal topology based on input/output voltage relationship and efficiency targets without changing the controller IC.
Is LT3756IUD-2#PBF suitable for automotive applications?
Yes, LT3756IUD-2#PBF is AEC-Q100 qualified for automotive applications (Grade I, –40°C to +125°C), features 100V input transient tolerance, integrated open LED and overvoltage protection, and robust thermal shutdown - making it ideal for headlamps, DRLs, and interior lighting systems.
LT3756IUD-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:
- 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#PBF FAQ
1.How can I place an order for LT3756IUD-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756IUD-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 LT3756IUD-2#PBF reliable?
The price and inventory of LT3756IUD-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 LT3756IUD-2#PBF is usually 5 days.
3.What payment methods are accepted for LT3756IUD-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756IUD-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756IUD-2#PBF?
LT3756IUD-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756IUD-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 LT3756IUD-2#PBF?
For technical support, including LT3756IUD-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756IUD-2#PBF requirements.
6.How does Aetrix verify that LT3756IUD-2#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756IUD-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 LT3756IUD-2#PBF meets industry standards.
7.What is the process for return or replacement of LT3756IUD-2#PBF?
All LT3756IUD-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756IUD-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 LT3756IUD-2#PBF part is unused and in its original packaging.
Return procedure for LT3756IUD-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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