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Analog Devices Inc. LT3756IUD-1#PBF
- Part No.:
- LT3756IUD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756IUD-1#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:111
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Product details
Overview
LT3756IUD-1#PBF from Analog Devices is a constant-current, constant-voltage DC/DC LED controller optimized for high-side current sensing in boost, buck, or buck-boost topologies. It features 100V input capability, 100V output support, 100 mV high-side current sense threshold, adjustable 100 kHz–1 MHz switching frequency, and AEC-Q100 qualification for automotive LED headlamp drivers.
For engineers reviewing the LT3756IUD-1#PBF datasheet, LT3756IUD-1#PBF pinout, LT3756IUD-1#PBF application, or LT3756IUD-1#PBF equivalent, key selection criteria include its 3000:1 PWM dimming ratio, open LED protection via FB-based fault detection, programmable undervoltage lockout with hysteresis, and compatibility with thermally demanding automotive ambient conditions (–40°C to 125°C).
Technical Context
The LT3756IUD-1#PBF implements fixed-frequency current-mode control with internal 7.15 V regulated INTVCC supply driving an N-channel MOSFET gate. Its dual-loop architecture supports simultaneous regulation of LED string current (via ISP/ISN differential sensing) and output voltage (via FB reference at 1.25 V), with cross-protection logic preventing overvoltage and open-circuit faults.
Unlike the base LT3756 and LT3756-2 variants, the LT3756-1 family adds frequency synchronization capability via the SYNC pin-replacing OPENLED functionality-and maintains identical current-sense threshold programming (100 mV full-scale), soft-start, and CTRL-based analog dimming behavior across all grades.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6 V to 100 V - supports wide-range automotive battery systems including cold-crank and load-dump transients. |
| Output Voltage Capability | Up to 100 V - enables single-stage high-brightness LED string drive without cascaded converters. |
| Current Sense Threshold | 100 mV (typical) - sets LED current ILED = 100 mV / RSENSE; low value minimizes power loss in sense resistor. |
| Switching Frequency Range | 100 kHz to 1 MHz - adjustable via RT resistor to balance efficiency, EMI, and magnetic component size. |
| Operating Temperature Range | –40°C to 125°C - qualified per AEC-Q100 Grade I for under-hood automotive lighting applications. |
| Dimming Support | 3000:1 true-color PWM dimming + analog dimming via CTRL pin - preserves color consistency across brightness levels. |
| Package | 16-lead (3 mm × 3 mm) QFN with exposed thermal pad - provides low θJA = 68°C/W for high-power density designs. |
Pinout & Package
LT3756IUD-1#PBF is housed in a thermally enhanced 16-lead (3 mm × 3 mm) plastic QFN package with exposed GND pad (Pin 17), requiring soldering to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives external NMOS disconnect switch; toggles low during FB overvoltage (>1.25 V + 60 mV) to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Regulates output voltage to 1.25 V; triggers OPENLED pull-down when <1.20 V (open LED detection). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; bias current ≤25 µA; enables short-circuit detection below 3 V common-mode. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high side; combined ISP/ISN differential threshold = 100 mV ±2 mV (full-scale). |
| VC (Pin 5) | Error amplifier output | Integrates loop error; high-impedance during PWM low to retain state; requires RC compensation network. |
| CTRL (Pin 6) | Analog dimming control | Programs current sense threshold: 0–1 V → linear scaling; >1.2 V → fixed 100 mV; enables precise analog dimming. |
| VREF (Pin 7) | 2 V reference output | Stable 2 V source (±20 mV) for CTRL divider or temperature compensation networks; drives ≤100 µA. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; controls oscillator, GATE, and PWMOUT; supports 3000:1 PWM dimming. |
| SS (Pin 10) | Soft-start timing | 10 µA internal current charges external capacitor; sets startup ramp time and prevents inrush current. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100 kΩ → ~100 kHz; 10 kΩ → ~1 MHz. |
| SHDN/UVLO (Pin 12) | Enable & undervoltage detect | 1.22 V falling threshold with user-programmable hysteresis; resets soft-start on UVLO event. |
| INTVCC (Pin 13) | Internal LDO output | 7.15 V regulated supply (±150 mV); powers gate driver and logic; requires 4.7 µF local ceramic bypass. |
| VIN (Pin 14) | Main power input | Accepts 6–100 V; must be bypassed with ≥0.22 µF ceramic capacitor near IC. |
| 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 N-channel FET between INTVCC and GND; rise/fall time ≤35 ns (3300 pF load). |
| GND (Pin 17) | Power & signal ground | Exposes thermal pad; serves as current sense return path; must be soldered to large copper area. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without ground-referenced LED strings. |
| SYNC input (LT3756-1 only) | Allows external clock synchronization to reduce EMI; replaces OPENLED function; requires RT set 20% slower than SYNC frequency. |
| Open LED protection | FB pin detects open-circuit condition (<1.20 V) and asserts OPENLED status (on LT3756/LT3756-2); LT3756IUD-1#PBF uses SYNC instead but retains same FB fault logic. |
| Programmable soft-start | External capacitor on SS pin controls startup dV/dt and inrush current; prevents overshoot during power-up. |
| Low shutdown current | <1 µA quiescent draw when SHDN/UVLO <0.4 V - critical for always-on automotive modules. |
| AEC-Q100 Grade I qualification | Validated for –40°C to 125°C operation with lifetime reliability testing per automotive standards. |
Applications
| Automotive Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving 30W white LED arrays in vehicle forward lighting with transient immunity up to 100V. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current while maintaining 100V output compliance during battery load dump. Use Value: 94% peak efficiency at 8–60V input enables compact thermal design; 3000:1 PWM dimming meets adaptive driving beam (ADB) requirements. | Use Scenario: Powering multi-string high-lumen LED fixtures in warehouse ceilings with 277VAC-derived DC bus. IC Role / Device Role / Timing Role: Buck-mode constant-current regulator accepting up to 100V input from rectified AC line; manages thermal derating across ambient range. Use Value: High-side sensing allows direct connection to positive-rail LED strings; AEC-Q100 qualification ensures long-term reliability in unattended industrial environments. |
| UV-C Disinfection Module | Battery-Powered Portable Light |
Use Scenario: Driving high-voltage UV-C LED arrays (36–72V) from 24V industrial power supplies with strict current stability. IC Role / Device Role / Timing Role: Precision current source with <±2% LED current regulation over temperature and line variations. Use Value: 100 mV sense threshold enables use of low-value, low-drift sense resistors; CTRL pin allows closed-loop thermal derating. | Use Scenario: Compact flashlight or inspection lamp powered by 2–4 Li-ion cells (6–16.8V) with smooth analog + PWM dimming. IC Role / Device Role / Timing Role: Boost-mode LED driver with integrated soft-start and low-IQ shutdown to maximize battery runtime. Use Value: <1 µA shutdown current extends shelf life; 16-pin QFN fits space-constrained handheld enclosures; 3000:1 dimming enables fine brightness control. |
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 frequency; no SYNC; no OPENLED/SYNC pin reassignment; lower max VIN (60V). | Targeted at non-automotive, lower-voltage industrial LED drivers where synchronization is not required. | Select when fixed frequency simplifies EMI filtering and 60V input ceiling is acceptable. |
| LT3762EFE#PBF | Higher 150V input rating; includes spread-spectrum modulation; no CTRL-based analog dimming; different pinout. | Suitable for harsher industrial or telecom power systems needing wider input range and EMI reduction. | Choose when input transients exceed 100V or spread-spectrum operation is mandated for regulatory compliance. |
Compared with LTC3783EFE#PBF, LT3756IUD-1#PBF offers higher input voltage tolerance and frequency synchronization, enabling robust automotive integration; versus LT3762EFE#PBF, it provides finer analog dimming control and smaller QFN packaging, better suited for space-constrained headlamp modules.
Availability
LT3756IUD-1#PBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial high-bay lighting, UV-C disinfection modules, and portable battery-powered LED lighting requiring stable component supply and AEC-Q100-compliant performance.
Supply support for LT3756IUD-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 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 designed specifically for high-reliability, high-efficiency LED current regulation in demanding environments - emphasizing wide input range, flexible topology support, and automotive-grade robustness.
FAQ
What is the primary function of the LT3756IUD-1#PBF in an LED driver circuit?
The LT3756IUD-1#PBF functions as a constant-current, constant-voltage DC/DC controller that regulates high-brightness LED strings using high-side current sensing. It drives an external N-channel MOSFET in boost, buck, or buck-boost configurations, supporting up to 100V input and output while delivering precise current control and comprehensive fault protection. Its design centers on reliability in automotive lighting applications.
How does the LT3756IUD-1#PBF differ from the standard LT3756 and LT3756-2 variants?
The LT3756IUD-1#PBF belongs to the LT3756-1 family, which replaces the OPENLED pin with a SYNC input for external clock synchronization - a feature absent in LT3756 and LT3756-2. All share identical current-sense architecture, 100mV threshold, CTRL-based analog dimming, and AEC-Q100 qualification, but only LT3756-1 supports frequency locking to reduce system-level EMI.
Can the LT3756IUD-1#PBF operate in buck mode with a 12V input driving a 5V LED string?
Yes, the LT3756IUD-1#PBF supports buck-mode operation and can regulate a 5V LED string from a 12V input. In buck configuration, the high-side current sense (ISP/ISN) remains functional, and the controller maintains constant-current regulation via the SENSE pin monitoring switch current. The FB pin may be used for optional constant-voltage backup or open-LED detection.
What thermal considerations apply to the LT3756IUD-1#PBF in continuous 30W LED driver designs?
The LT3756IUD-1#PBF uses a 3mm × 3mm QFN with exposed thermal pad (θJA = 68°C/W). For 30W output, PCB layout must include ≥2 in² of 2-oz copper connected to Pin 17 (GND) to maintain junction temperature ≤125°C. Thermal vias under the pad and airflow or heatsinking are recommended in enclosed automotive housings.
Is the LT3756IUD-1#PBF pin-compatible with other LT3756 variants in the same package?
Yes - the LT3756IUD-1#PBF shares identical 16-pin QFN pinout and footprint with LT3756IUD#PBF and LT3756IUD-2#PBF. However, the SYNC pin (Pin 9) on LT3756IUD-1#PBF replaces OPENLED functionality present on other variants, so PCB designs must route Pin 9 to a sync source rather than a pull-up resistor or fault indicator.
LT3756IUD-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:
- 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-1#PBF FAQ
1.How can I place an order for LT3756IUD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756IUD-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 LT3756IUD-1#PBF reliable?
The price and inventory of LT3756IUD-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 LT3756IUD-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3756IUD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756IUD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756IUD-1#PBF?
LT3756IUD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756IUD-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 LT3756IUD-1#PBF?
For technical support, including LT3756IUD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756IUD-1#PBF requirements.
6.How does Aetrix verify that LT3756IUD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3756IUD-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 LT3756IUD-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3756IUD-1#PBF?
All LT3756IUD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756IUD-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 LT3756IUD-1#PBF part is unused and in its original packaging.
Return procedure for LT3756IUD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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