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Analog Devices Inc. LT3756EUD-1#TRPBF
- Part No.:
- LT3756EUD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756EUD-1#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,132
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Product details
Overview
LT3756EUD-1#TRPBF from Analog Devices is a high-voltage constant-current LED controller designed for automotive and industrial LED drivers. It operates from 6V to 100V input, delivers up to 100V output, supports 100kHz–1MHz adjustable switching frequency, features high-side current sensing with 100mV threshold, and enables 3000:1 PWM dimming - used in white LED headlamp drivers requiring robust open-LED protection and AEC-Q100-compliant operation.
For engineers reviewing the LT3756EUD-1#TRPBF datasheet, LT3756EUD-1#TRPBF pinout, LT3756EUD-1#TRPBF application, or LT3756EUD-1#TRPBF equivalent, key selection criteria include its frequency synchronization capability (LT3756-1 variant), 16-pin 3mm×3mm QFN package with exposed thermal pad, -40°C to +125°C operating range, and dual regulation modes (constant-current and constant-voltage) with ground-referenced FB pin.
Technical Context
The LT3756EUD-1#TRPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator driving an external N-channel MOSFET. Its architecture supports boost, buck, buck-boost, SEPIC, and flyback topologies via high-side current sensing at ISP/ISN pins and ground-referenced voltage feedback at FB.
It integrates frequency synchronization (SYNC pin replaces OPENLED), programmable soft-start (SS pin), analog dimming via CTRL pin (0–1.1V linear adjustment of 100mV current sense threshold), and dual-protection logic: open-LED detection (FB < VFB – 50mV) and overvoltage shutdown (FB > VFB + 60mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range automotive battery systems including cold-crank and load-dump transients. |
| Output Voltage Capability | Up to 100V - enables driving long LED strings in headlamps and signage without cascading converters. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor; higher frequencies reduce inductor size but increase switching losses. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side sensing with minimal power dissipation in RSENSE. |
| Dimming Ratio | 3000:1 true-color PWM - preserves LED chromaticity across full brightness range for automotive lighting compliance. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade 1 for under-hood and exterior lighting applications. |
| Package | 16-lead 3mm × 3mm QFN with exposed GND pad - provides low thermal resistance (θJA = 68°C/W) for high-power LED driver thermal management. |
Pinout & Package
LT3756EUD-1#TRPBF 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 | Drives LED disconnect NMOS; toggles low during FB overvoltage (> VFB + 60mV) to isolate load and prevent LED damage. |
| FB (Pin 2) | Voltage feedback input | Ground-referenced node for CV regulation or open-LED detection; regulates to 1.25V nominal; asserts OPENLED when < VFB – 50mV. |
| ISN (Pin 3) | Negative current sense input | Connects to low side of high-side sense resistor; enables short-circuit detection when VISN < 3V and |ISP–ISN| > 150mV. |
| ISP (Pin 4) | Positive current sense input | Connects to high side of sense resistor; bias current varies with CTRL voltage; part of differential current measurement path. |
| VC (Pin 5) | Error amplifier output | High-impedance transconductance output; stores demand state during PWM low; stabilized by RC network to GND. |
| CTRL (Pin 6) | Analog dimming control | Adjusts ISP–ISN current threshold from 0 to 100mV (0–1.1V input); enables smooth analog dimming without color shift. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%); supplies bias for CTRL divider or temperature compensation networks; drives ≤100µA. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; disables switching and idles oscillator when low; synchronizes PWMOUT. |
| SS (Pin 9) | Soft-start timing | 10µA pull-up to 2.5V rail; external capacitor sets startup ramp time; reset by UVLO or thermal fault. |
| RT (Pin 10) | Frequency programming | Resistor-to-GND sets oscillator frequency (100kΩ → ~100kHz; 10kΩ → ~1MHz); replaces SYNC function on LT3756-1. |
| SHDN/UVLO (Pin 11) | Enable & undervoltage lockout | 1.22V falling threshold with programmable hysteresis; sub-µA shutdown current (<1µA) when pulled ≤0.4V. |
| INTVCC (Pin 12) | Internal LDO supply | 7.15V regulated output (±150mV); powers gate driver and logic; requires 4.7µF ceramic bypass close to pin. |
| VIN (Pin 13) | Main input supply | Accepts 6–100V; local 0.22µF+ ceramic bypass required; powers INTVCC LDO and internal circuitry. |
| SENSE (Pin 14) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current; clamped at 108mV typical limit. |
| GATE (Pin 15) | MOSFET gate driver | Drives external N-channel FET between INTVCC and GND; fast rise/fall times (35ns @ 3.3nF); disabled during fault/shutdown. |
| GND (Pin 16) | Power and signal ground | Reference for SENSE, ISN, and exposed thermal pad; must be low-impedance plane connection for stability and thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Frequency synchronization | SYNC pin (replaces OPENLED on LT3756-1) allows external clock alignment to reduce EMI in multi-converter systems. |
| High-side current sensing | ISP/ISN inputs support topology flexibility - enables buck, boost, buck-boost, SEPIC, and flyback configurations without ground loop issues. |
| Dual regulation mode | Simultaneous CC/CV operation: FB regulates output voltage while ISP/ISN regulate LED current - critical for hybrid LED+capacitor hold-up designs. |
| Open-LED fault signaling | OPENLED pin (on LT3756 and LT3756-2) pulls down when FB drops below VFB – 50mV - provides fail-safe status for automotive diagnostics. |
| Programmable soft-start | SS pin controls startup dV/dt and inrush current via external capacitor - prevents input voltage sag and inductor saturation during turn-on. |
| AEC-Q100 qualification | Qualified for automotive Grade 1 (–40°C to +125°C) - meets reliability, ESD, and transient immunity requirements for front-end lighting modules. |
Applications
| Automotive LED Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current control and dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current controller managing individual LED segments via PWM dimming and analog current scaling. Use Value: 3000:1 true-color PWM dimming preserves correlated color temperature (CCT) across full intensity range, meeting UNECE R149 photometric standards. |
Use Scenario: 100W+ high-bay luminaires in warehouses with 277VAC input and 48–96V LED strings. IC Role / Device Role / Timing Role: Primary DC/DC controller in isolated flyback or non-isolated buck-boost stage delivering stable current despite line fluctuations. Use Value: 100V input rating handles brownouts and surges on industrial mains; high-side sensing avoids ground-referenced current measurement errors. |
| UV-C Sterilization Modules | Stage & Architectural LED Drivers |
Use Scenario: Pulsed UV-C LED arrays (265nm) for surface disinfection requiring precise current pulses and thermal derating. IC Role / Device Role / Timing Role: Current-regulated pulse generator with programmable frequency and soft-start to manage thermal stress on GaN LEDs. Use Value: Adjustable 100kHz–1MHz switching enables optimal trade-off between efficiency and pulse fidelity; CTRL pin allows real-time current derating based on temperature feedback. |
Use Scenario: Color-tunable RGBW fixtures with independent channel control and DALI/DMX interface. IC Role / Device Role / Timing Role: Per-channel constant-current driver supporting analog (CTRL) and digital (PWM) dimming inputs for smooth color mixing. Use Value: Ground-referenced FB pin simplifies integration with microcontroller-based voltage monitoring; 16-pin QFN enables compact multi-channel PCB layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756EUD#TRPBF | No SYNC pin; OPENLED pin present; base variant without synchronization capability. | Suitable where standalone operation or asynchronous multi-channel control is acceptable. | Select when system-level clock synchronization is unnecessary and open-LED status reporting is required. |
| LT3756EUD-2#TRPBF | Includes improved OPENLED status latching and fault recovery logic; no SYNC pin. | Better suited for safety-critical open-circuit detection in medical or emergency lighting. | Choose when robust fault persistence and re-assertion behavior after overvoltage events is prioritized over synchronization. |
Compared with LT3756EUD#TRPBF, the LT3756EUD-1#TRPBF adds frequency synchronization for EMI reduction in multi-controller systems but removes OPENLED functionality; compared with LT3756EUD-2#TRPBF, it trades enhanced fault reporting for sync capability - making LT3756EUD-1#TRPBF optimal for synchronized LED arrays in automotive ADAS lighting.
Availability
LT3756EUD-1#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial high-bay lighting, UV-C sterilization modules, and architectural LED drivers requiring stable component supply, AEC-Q100 compliance, and production-ready thermal packaging.
Supply support for LT3756EUD-1#TRPBF 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, and automotive electronics markets.
The LT3756 family is designed specifically for high-reliability, high-voltage LED driver applications - emphasizing wide input range, topology flexibility, and automotive-grade robustness in compact QFN and MSOP packages.
FAQ
What is the key functional difference between LT3756EUD-1#TRPBF and the base LT3756EUD#TRPBF?
The LT3756EUD-1#TRPBF replaces the OPENLED pin with a SYNC pin for external clock synchronization, enabling coordinated switching across multiple controllers to reduce conducted EMI. Unlike the base LT3756EUD#TRPBF, it does not provide open-LED fault indication but supports tighter timing control in multi-phase or multi-string LED systems - a critical distinction for automotive adaptive lighting clusters where EMI compliance is mandatory.
Does LT3756EUD-1#TRPBF support both constant-current and constant-voltage regulation simultaneously?
Yes, LT3756EUD-1#TRPBF supports concurrent CC/CV regulation: ISP/ISN pins regulate LED current while the FB pin regulates output voltage. The internal error amplifiers interact such that neither loop dominates unintentionally - for example, if LED string voltage rises due to temperature drift, FB feedback reduces duty cycle to maintain safe voltage, while ISP/ISN maintains target current. This dual-loop behavior is confirmed in the device's block diagram and operational description on page 11 of the datasheet.
What is the maximum recommended switching frequency for LT3756EUD-1#TRPBF in a 30W automotive headlamp design?
The LT3756EUD-1#TRPBF supports up to 1MHz switching, but for a 30W automotive headlamp using a discrete N-MOSFET, Analog Devices recommends 300–500kHz as the optimal range. At 500kHz, the RT resistor is ~26.7kΩ (per Figure 7), balancing inductor size reduction against gate drive losses and INTVCC loading - especially important given the 17mA INTVCC current limit and 7.15V LDO dropout constraints under transient conditions.
How does the CTRL pin on LT3756EUD-1#TRPBF enable analog dimming, and what is its effective range?
The CTRL pin on LT3756EUD-1#TRPBF linearly adjusts the ISP–ISN current sense threshold from 0mV to 100mV over 0V to 1.1V input. Below 1V, threshold = 0.1 × VCTRL; above 1.2V, it holds at 100mV full scale. This allows smooth analog dimming without PWM-induced flicker or color shift - verified by the "V(ISP–ISN) Threshold vs VCTRL" curve (Figure 3) and electrical characteristics table showing ±2% linearity across –40°C to +125°C.
Is LT3756EUD-1#TRPBF pin-compatible with other variants in the LT3756 family, such as LT3756EUD-2#TRPBF?
No, LT3756EUD-1#TRPBF is not pin-compatible with LT3756EUD-2#TRPBF: Pin 3 is SYNC on LT3756EUD-1#TRPBF but OPENLED on LT3756EUD-2#TRPBF, and Pin 9 is SS on both but functions identically. Swapping them without board revision risks misconfigured fault signaling or loss of synchronization. The datasheet explicitly assigns different pin functions per variant in the "PIN CONFIGURATION" section (pages 2–3), confirming non-interchangeability at the hardware level.
LT3756EUD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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-1#TRPBF FAQ
1.How can I place an order for LT3756EUD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756EUD-1#TRPBF 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-1#TRPBF reliable?
The price and inventory of LT3756EUD-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3756EUD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3756EUD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756EUD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756EUD-1#TRPBF?
LT3756EUD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756EUD-1#TRPBF 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-1#TRPBF?
For technical support, including LT3756EUD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756EUD-1#TRPBF requirements.
6.How does Aetrix verify that LT3756EUD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3756EUD-1#TRPBF 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-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3756EUD-1#TRPBF?
All LT3756EUD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756EUD-1#TRPBF, 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-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3756EUD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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