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Analog Devices Inc. LT3756EUD-2#TRPBF
- Part No.:
- LT3756EUD-2#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3756EUD-2#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,821
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Product details
Overview
LT3756EUD-2#TRPBF 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 features high-side current sensing for boost/buck/buck-boost topologies. It drives external N-channel MOSFETs with a regulated 7.15V gate supply and integrates open-LED protection with improved status signaling.
For engineers reviewing the LT3756EUD-2#TRPBF datasheet, LT3756EUD-2#TRPBF pinout, LT3756EUD-2#TRPBF application, or LT3756EUD-2#TRPBF equivalent, this page provides verified technical context, exact pin functions, real-world dimming performance, thermal design guidance for QFN packages, and validated alternative options for LED driver system design.
Technical Context
The LT3756EUD-2#TRPBF implements fixed-frequency current-mode control with internal slope compensation, enabling stable regulation across wide VIN (6–100V) and VOUT (up to 100V) ranges. Its high-side current sense architecture (ISP/ISN inputs) supports flexible topology selection-boost, buck, buck-boost, SEPIC, or flyback-without requiring ground-referenced LED strings.
It features dual-loop regulation: the ISP–ISN differential voltage sets LED current (100mV full-scale threshold), while FB regulates output voltage (1.25V reference). The LT3756-2 variant adds enhanced OPENLED latching behavior-reasserting fault status after overvoltage events subside-distinguishing it from LT3756 and LT3756-1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports 12V/24V/48V systems with 100V transient tolerance for automotive cold-crank and load-dump immunity. |
| Output Voltage Capability | Up to 100V - enables driving long LED strings (e.g., 30× white LEDs @ 3.3V) in high-brightness headlamp or signage applications. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side current sensing with ≤0.1% gain error over temperature. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor; higher frequencies reduce inductor size but increase switching losses. |
| Dimming Ratio | 3000:1 true-color PWM dimming - preserves LED chromaticity across full brightness range without color shift. |
| Package & Thermal | 16-lead 3mm × 3mm QFN with exposed pad - θJA = 68°C/W; requires soldered GND pad for thermal reliability in 30W+ designs. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade E for under-hood automotive LED driver use. |
Pinout & Package
LT3756EUD-2#TRPBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed GND pad (Pin 17), which must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output / Overvoltage protection signal | Drives external NMOS disconnect switch; pulled low when FB exceeds VFB + 60mV to isolate LED string during overvoltage faults. |
| FB (Pin 2) | Voltage feedback input | Regulates output voltage to 1.25V reference; also triggers OPENLED pull-down when FB falls below VFB – 50mV (open-LED detection). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; bias current <25µA; enables short-circuit detection when ISN < 3V and ISP–ISN > 150mV. |
| ISP (Pin 4) | Positive current sense input | High-side current sense input; common-mode range up to 100V; bias current varies with CTRL voltage (≤55µA max). |
| VC (Pin 5) | Error amplifier output | Integrates ISP–ISN vs. CTRL-set threshold; high-impedance during PWM low to retain state for analog dimming continuity. |
| CTRL (Pin 6) | Current threshold adjustment | Sets LED current sense threshold from 0 to 100mV linearly (0–1V) then clamps; enables analog dimming and thermal derating. |
| VREF (Pin 7) | 2.0V precision reference output | Stable 2.0V source (±1.5%); supplies up to 100µA for CTRL divider or external temperature compensation circuits. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; controls GATE/PWMOUT directly; supports 3000:1 PWM dimming with minimal latency. |
| OPENLED (Pin 9) | Open-LED fault indicator | Open-collector output; pulls down when FB < VFB – 50mV; LT3756-2 reasserts after overvoltage clears (enhanced latching). |
| SS (Pin 10) | Soft-start timing input | 10µA internal pull-up to 2.5V rail; external capacitor sets ramp time; reset by UVLO or thermal shutdown. |
| RT (Pin 11) | Frequency programming input | Resistor-to-GND sets oscillator frequency (100kHz–1MHz); 26.7kΩ yields ~375kHz typical for efficiency/size trade-off. |
| SHDN/UVLO (Pin 12) | Shutdown & undervoltage lockout | 1.22V falling threshold with programmable hysteresis; <1µA shutdown IQ; enables brown-in/out protection for system robustness. |
| INTVCC (Pin 13) | Internal LDO output (7.15V) | Supplies gate driver, PWMOUT, and internal logic; requires 4.7µF ceramic bypass; current-limited to 17mA (typ) for FET drive. |
| VIN (Pin 14) | Main power input | Accepts 6–100V; must be locally bypassed with ≥0.22µF ceramic capacitor near pin; powers INTVCC LDO. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current; limits at 108mV (typ) to prevent FET overcurrent. |
| GATE (Pin 16) | N-MOSFET gate driver output | Drives external FET gate between INTVCC and GND; rise/fall time <35ns (CL = 3300pF); disables during fault or shutdown. |
| GND (Pin 17) | Power & signal ground / Exposed pad | Reference for SENSE, ISN, and internal circuits; exposed pad must be soldered to PCB plane for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost) without grounding LED cathode-critical for isolated or floating-string designs. |
| Enhanced OPENLED latching (LT3756-2) | Reasserts open-LED fault after overvoltage condition clears, improving diagnostic reliability in automotive lighting systems. |
| Programmable 100kHz–1MHz switching | Allows optimization of magnetic size (higher fSW) vs. efficiency (lower fSW) without changing IC; RT resistor sets exact frequency. |
| 100mV high-side current sense threshold | Minimizes power loss in sense resistor (e.g., 0.1Ω yields 10W dissipation at 10A), supporting high-power LED arrays. |
| AEC-Q100 Grade E qualification | Validated for automotive under-hood operation (–40°C to +125°C), including HTOL, TC, and ESD testing per automotive standards. |
| Integrated 7.15V gate driver supply | Eliminates need for external bias supply; regulates from VIN; supports fast-switching N-MOSFETs with low QG requirements. |
Applications
| Automotive Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
|
Use Scenario: 30W white LED headlamp module in passenger vehicle, operating from 9–16V battery with 100V load-dump transients. IC Role / Device Role / Timing Role: Constant-current controller regulating 700mA LED string; manages PWM dimming for DRL/low-beam/high-beam modes. Use Value: 94% efficiency at 12V input enables compact thermal design; 3000:1 dimming preserves color fidelity; AEC-Q100 ensures field reliability. |
Use Scenario: 100W LED fixture for warehouse lighting, powered from 24–48V DC distribution bus with surge immunity requirements. IC Role / Device Role / Timing Role: Buck-mode LED driver controlling 1.5A current through 60V LED string; synchronized to building-wide DALI dimming signals. Use Value: High-side sensing allows direct connection to positive-rail LED strings; 100V output headroom accommodates aging LED Vf drift over 50,000 hours. |
| UV-C Disinfection System | Stage & Architectural Lighting |
|
Use Scenario: Pulsed UV-C LED array (275nm) for surface disinfection, requiring precise current control and rapid on/off cycling. IC Role / Device Role / Timing Role: Constant-current source delivering 1.2A pulses at 1kHz; uses PWM input for microsecond-level duty-cycle control. Use Value: 100mV sense threshold minimizes heat in current shunt; fast gate driver (<35ns) enables clean pulse edges; open-LED detection prevents lamp damage. |
Use Scenario: RGBW tunable LED luminaire with independent channel control, powered from 48V PoE++ infrastructure. IC Role / Device Role / Timing Role: Four-channel constant-current driver (one LT3756EUD-2#TRPBF per channel); each regulates R/G/B/W string independently. Use Value: CTRL pin enables analog dimming per channel for smooth CCT tuning; FB loop supports constant-voltage auxiliary loads (e.g., sensors, comms ICs). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756IMSE-2#TRPBF | Same functionality and specs, but in 16-lead MSOP package (θJA = 43°C/W); no exposed thermal pad. | Better suited for space-constrained layouts where QFN reflow is challenging; lower thermal performance limits max continuous power. | Select when board assembly process favors MSOP or when thermal load is ≤20W; verify layout copper area for MSOP thermal relief. |
| LT3762EFE#TRPBF | Pin-compatible successor with wider 4.5–100V VIN, 150V VOUT, and integrated 5V bias supply; same QFN-16 package. | Supports higher-output LED strings and eliminates need for external INTVCC bypass cap; includes spread-spectrum for EMI reduction. | Choose for new designs needing extended voltage range or reduced BOM count; not drop-in due to different VREF (1.22V) and CTRL scaling. |
Compared with LT3756IMSE-2#TRPBF, the LT3756EUD-2#TRPBF offers superior thermal performance (68°C/W vs. 43°C/W) and smaller footprint, making it preferred for 30W+ headlamp designs; versus LT3762EFE#TRPBF, it lacks spread-spectrum and integrated bias but maintains proven AEC-Q100 qualification and simpler analog interface.
Availability
LT3756EUD-2#TRPBF is available at Aetrix Electronics and suitable for automotive lighting, industrial high-bay fixtures, UV-C disinfection systems, and architectural LED applications requiring stable component supply, AEC-Q100 compliance, and high-voltage robustness.
Supply support for LT3756EUD-2#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 (now part of Analog Devices, Inc., a subsidiary of Analog Devices, Inc.) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.
The LT3756 family was designed specifically for high-reliability, high-voltage LED driver applications-including automotive headlamps and industrial lighting-where precise current regulation, fault resilience, and thermal efficiency are critical.
FAQ
What is the key functional difference between LT3756EUD-2#TRPBF and LT3756EUD#TRPBF?
The LT3756EUD-2#TRPBF implements an enhanced OPENLED latching behavior: after an overvoltage event causes FB to exceed VFB + 60mV and de-assert OPENLED, the LT3756EUD-2#TRPBF will re-assert OPENLED once FB falls back below the overvoltage threshold but remains above the open-LED threshold (VFB – 50mV). The base LT3756EUD#TRPBF does not re-assert until FB drops below both thresholds. This improves fault reporting fidelity in automotive systems.
Can LT3756EUD-2#TRPBF operate in buck mode with a grounded LED cathode?
Yes, LT3756EUD-2#TRPBF supports buck-mode operation with grounded LED cathodes using its high-side current sense architecture. Connect the LED string between input (VIN) and switch node, with ISP to switch node and ISN to the sense resistor's low side. The controller regulates current through the LED regardless of topology-boost, buck, buck-boost, SEPIC, or flyback-as confirmed in the datasheet's "Applications" section and block diagram.
What is the minimum recommended capacitor value for INTVCC bypass on LT3756EUD-2#TRPBF?
The minimum recommended capacitor for INTVCC bypass on LT3756EUD-2#TRPBF is 4.7µF, using a 10V-rated X7R or X5R ceramic capacitor placed as close as possible to the INTVCC pin and GND. This value ensures stable gate driver operation and handles peak switching currents; larger values (e.g., 10µF) may improve transient response but are not required for basic functionality.
Does LT3756EUD-2#TRPBF require external components for soft-start, and how is it configured?
Yes, LT3756EUD-2#TRPBF requires an external capacitor on the SS (soft-start) pin to configure ramp time. A 10µA internal current source charges the capacitor from 0V to 2.5V; soft-start duration ≈ (CSS × 2.5V) / 10µA. For example, a 100nF capacitor yields ~25ms ramp. The SS pin is reset to GND during UVLO or thermal shutdown, ensuring controlled restart after fault conditions.
How does the CTRL pin function for analog dimming in LT3756EUD-2#TRPBF?
In LT3756EUD-2#TRPBF, the CTRL pin adjusts the ISP–ISN current sense threshold linearly from 0 to 100mV as VCTRL rises from 0V to 1V; above 1.2V, the threshold clamps at 100mV. This enables analog dimming by varying CTRL voltage-e.g., using a DAC or thermistor divider-to scale LED current proportionally while maintaining regulation accuracy and stability across temperature.
LT3756EUD-2#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-2#TRPBF FAQ
1.How can I place an order for LT3756EUD-2#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3756EUD-2#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-2#TRPBF reliable?
The price and inventory of LT3756EUD-2#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-2#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3756EUD-2#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3756EUD-2#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3756EUD-2#TRPBF?
LT3756EUD-2#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3756EUD-2#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-2#TRPBF?
For technical support, including LT3756EUD-2#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3756EUD-2#TRPBF requirements.
6.How does Aetrix verify that LT3756EUD-2#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3756EUD-2#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-2#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3756EUD-2#TRPBF?
All LT3756EUD-2#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3756EUD-2#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-2#TRPBF part is unused and in its original packaging.
Return procedure for LT3756EUD-2#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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