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Analog Devices Inc. LT3476EUHF#PBF
- Part No.:
- LT3476EUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LT3476EUHF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,915
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Product details
Overview
LT3476EUHF#PBF from Analog Devices (formerly Linear Technology) is a quad-output, constant-current DC/DC LED driver IC with high-side current sensing, 1.5A internal NPN switches, and independent PWM dimming per channel. It operates from 2.8V to 16V input, supports buck/boost/buck-boost topologies, and delivers up to 1A per channel for automotive lighting, TFT LCD backlighting, and RGB LED arrays.
For engineers reviewing the LT3476EUHF#PBF datasheet, LT3476EUHF#PBF pinout, LT3476EUHF#PBF application, or LT3476EUHF#PBF equivalent, key selection criteria include its 38-lead QFN package, 200kHz–2MHz programmable switching frequency, ±2.5% current sense threshold accuracy, open-LED protection, and True Color PWM dimming supporting up to 1000:1 ratio at 100Hz.
Technical Context
The LT3476EUHF#PBF implements a fixed-frequency, current-mode control architecture with four independent switching regulators. Each channel features a dedicated VADJ pin to set LED current sense threshold from 10mV to 120mV, and a VC compensation pin enabling stable loop response across wide input/output voltage ranges.
It uses high-side current sensing via external resistors between CAPn and LEDn pins, allowing flexible topology implementation. Internal overvoltage protection clamps CAPn nodes at 33.5V (min), and thermal shutdown activates at 145°C. The RT pin sets oscillator frequency with ±10% tolerance over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.8V to 16V - supports single-cell Li-ion up to 4S battery inputs and industrial 12V rails. |
| Max Output Current per Channel | 1.5A - enables driving high-brightness LED strings without external MOSFETs. |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT resistor to balance efficiency vs. component size. |
| Current Sense Threshold Accuracy | ±2.5% at 105mV full scale - ensures precise LED current matching across channels. |
| Operating Junction Temp | –40°C to 85°C - qualified for automotive cabin and avionic display environments. |
| Package | 38-lead 5mm × 7mm QFN with exposed thermal pad - provides low θJC = 2°C/W for high-power LED driver thermal management. |
| Shutdown Current | <10µA - enables ultra-low power standby in always-on lighting systems. |
Pinout & Package
LT3476EUHF#PBF is housed in a thermally enhanced 38-lead plastic QFN (5mm × 7mm) with exposed GND pad (Pin 39) requiring soldering to PCB ground plane for electrical integrity and thermal dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC1–VC4 (Pins 1,12,13,38) | Error amplifier output | Drives external compensation network; floats during PWM off to preserve regulation state. |
| LED1–LED4 (Pins 2,5,8,11) | Non-inverting current sense input | Connects to high-side of external sense resistor; regulated to 0.1×VADJ below CAPn. |
| CAP1–CAP4 (Pins 3,4,9,10) | Inverting current sense input | Connects to low-side of sense resistor and output filter capacitor; triggers OVP if >33.5V. |
| VADJ1–VADJ4 (Pins 14,15,36,37) | Current threshold reference | Sets full-scale sense voltage from 10mV to 120mV; REF-connected yields 105mV nominal. |
| PWM1–PWM4 (Pins 16,17,34,35) | Channel enable/dimming control | Logic-low disables switch, reduces quiescent current, and preserves VC charge for fast recovery. |
| SHDN (Pin 18) | Global enable | High >1.5V enables all channels; low <0.4V places device in sub-10µA shutdown mode. |
| RT (Pin 6) | Oscillator frequency programming | Resistor to GND sets switching frequency; 21kΩ yields ~1MHz typical operation. |
| REF (Pin 7) | 1.05V precision reference | Stable output used to bias VADJ pins or drive resistor dividers for current scaling. |
| GND (Pin 39) | Signal and power ground | Exposed thermal pad must be soldered to PCB ground plane for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM dimming | Enables 1000:1 dimming ratio at 100Hz without color shift by preserving VC state during PWM off-time. |
| Independent channel control | Four fully isolated regulators allow mixed-topology designs (e.g., two buck + two boost) on single die. |
| High-side current sensing | Eliminates need for low-side shunt, enabling common-cathode LED configurations and simplifying layout. |
| Open-LED protection | Dedicated OVP per channel clamps CAPn at 33.5V to prevent SW node overvoltage during LED string failure. |
| Thermally optimized package | 38-lead QFN with exposed pad achieves θJC = 2°C/W, enabling 100W+ total output in compact footprint. |
Applications
| Automotive Headlight Control | TFT LCD Backlight Driver |
|---|---|
Use Scenario: Driving white LED arrays in adaptive front lighting systems (AFS) with dynamic beam shaping. IC Role / Device Role / Timing Role: Quad-channel constant-current source regulating four independent LED zones with synchronized PWM dimming. Use Value: Enables precise luminance control across zones using 1000:1 PWM dimming while maintaining color consistency under varying thermal conditions. |
Use Scenario: Powering edge-lit LCD backlights in industrial HMIs and avionics displays requiring uniform brightness and EMI compliance. IC Role / Device Role / Timing Role: High-efficiency buck-boost LED driver delivering 1A per channel with programmable frequency to minimize conducted noise. Use Value: Achieves >92% peak efficiency at 1A output and supports 2.8V–16V input range for compatibility with diverse vehicle and aircraft power buses. |
| RGB LED Color Mixing | Avionic Panel Lighting |
Use Scenario: Controlling red/green/blue LED strings in architectural and signage applications requiring accurate chromaticity. IC Role / Device Role / Timing Role: Independent current regulation per color channel with matched sense thresholds (±2.5%) for stable white-point maintenance. Use Value: Delivers consistent color output across temperature (-40°C to 85°C) and supply variation via high-side sensing and VADJ trimming. |
Use Scenario: Providing fail-safe illumination for cockpit instrument panels where reliability and open-circuit detection are critical. IC Role / Device Role / Timing Role: Quad-output driver with per-channel OVP and thermal shutdown protecting against LED string disconnection or overheating. Use Value: Ensures continuous operation with automatic fault containment-single channel failure does not affect others due to independent regulation loops. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3409QMY/NOPB | Single-channel controller with external MOSFET; no integrated switch or multi-channel capability. | Requires four separate ICs + FETs to match LT3476EUHF#PBF's quad integration; higher BOM count and layout area. | Select when higher voltage (>36V) or higher current (>1.5A) per channel is needed beyond LT3476EUHF#PBF's internal switch limits. |
| MAX16820ATL+ | Quad-channel but uses low-side current sensing; lacks high-side flexibility and True Color PWM preservation. | Cannot support common-cathode LED topologies; dimming recovery slower due to lack of VC float feature. | Prefer for cost-sensitive, non-automotive applications where topology constraints allow low-side sensing and 500:1 dimming suffices. |
Compared with LM3409QMY/NOPB and MAX16820ATL+, the LT3476EUHF#PBF offers superior integration (four 1.5A switches in one QFN), high-side sensing for topology freedom, and hardware-optimized True Color PWM-reducing design effort and board space for demanding lighting systems.
Availability
LT3476EUHF#PBF is available at Aetrix Electronics and suitable for automotive lighting, avionic panel illumination, TFT LCD backlighting, and RGB LED color-mixing applications requiring stable component supply and long-term production continuity.
Supply support for LT3476EUHF#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 acquired Linear Technology in 2017 and maintains its high-performance analog product lines, including precision power management ICs for demanding industrial and automotive applications.
The LT3476EUHF#PBF belongs to Linear's high-current LED driver family, designed specifically for multi-string, high-reliability lighting systems requiring independent channel control, robust fault protection, and thermal resilience.
FAQ
What is the maximum LED string voltage the LT3476EUHF#PBF can support in boost configuration?
The LT3476EUHF#PBF supports up to 33.5V at its CAPn pins, with internal overvoltage protection triggering at 33.5V (min). In boost mode, this allows driving LED strings with forward voltages up to ~30V depending on diode drop and layout losses. Exceeding 33.5V at CAPn disables switching to protect the internal NPN switch. The LT3476EUHF#PBF datasheet specifies absolute max CAP/LED rating as 36V, but functional OVP clamp is 33.5V.
Does the LT3476EUHF#PBF support buck, boost, and buck-boost topologies with the same pin connections?
Yes - the LT3476EUHF#PBF's high-side current sensing architecture enables all three topologies using the same CAPn/LEDn/SWn pin assignments. In buck mode, SWn connects to inductor input and LED cathode; in boost, SWn connects to inductor output and diode anode. No pin reconfiguration is needed - only external component placement changes per topology. The LT3476EUHF#PBF block diagram and typical applications confirm this flexibility.
How does the LT3476EUHF#PBF achieve 1000:1 PWM dimming without color shift?
The LT3476EUHF#PBF implements True Color PWM by floating the VCn pins during PWM low periods, preserving the error amplifier's stored compensation charge. This eliminates recovery delay when PWM resumes, ensuring identical current regulation start points across dimming cycles. Combined with independent channel control and matched current sense thresholds (±2.5%), it maintains consistent LED forward voltage and chromaticity - critical for RGB mixing. The LT3476EUHF#PBF datasheet confirms 1000:1 ratio at 100Hz in TA02 waveform.
What thermal derating applies to the LT3476EUHF#PBF at 85°C ambient?
At 85°C ambient with standard 2-layer PCB and 2cm² copper pour under the exposed pad, the LT3476EUHF#PBF junction temperature reaches ~115°C at full 1.5A per channel (6A total), staying within its 125°C max rating. Derating is minimal up to 85°C ambient due to θJC = 2°C/W and low RDS(ON) of internal NPN switches. The LT3476EUHF#PBF thermal characteristics table specifies TJ(max) = 125°C and θJA = 34°C/W, confirming safe operation at rated load in commercial temperature grade.
Can the LT3476EUHF#PBF drive eight LEDs per channel as shown in the typical application?
Yes - the LT3476EUHF#PBF's 36V SWn and CAPn ratings support up to eight white LEDs (3.6V VF each = 28.8V) in series per channel, with margin for diode drop and ripple. The "100W Quad 1A × 8 LED Driver" headline and TA05 schematic explicitly show eight-LED strings. Total output power depends on topology: in buck mode with VIN = 12V, eight LEDs require ~30V at CAPn, so boost or buck-boost is required - which the LT3476EUHF#PBF supports natively.
LT3476EUHF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 4
- Voltage - Supply (Min):
- 2.8V
- Voltage - Supply (Max):
- 16V
- Voltage - Output:
- 2.2V ~ 36V
- Current - Output / Channel:
- 1.5A (Switch)
- Frequency:
- 200kHz ~ 2MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LT3476EUHF#PBF FAQ
1.How can I place an order for LT3476EUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3476EUHF#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 LT3476EUHF#PBF reliable?
The price and inventory of LT3476EUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3476EUHF#PBF is usually 5 days.
3.What payment methods are accepted for LT3476EUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3476EUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3476EUHF#PBF?
LT3476EUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3476EUHF#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 LT3476EUHF#PBF?
For technical support, including LT3476EUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3476EUHF#PBF requirements.
6.How does Aetrix verify that LT3476EUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3476EUHF#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 LT3476EUHF#PBF meets industry standards.
7.What is the process for return or replacement of LT3476EUHF#PBF?
All LT3476EUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3476EUHF#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 LT3476EUHF#PBF part is unused and in its original packaging.
Return procedure for LT3476EUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3476EUHF#PBF Tags
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