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Analog Devices Inc. LT3476EUHF#TRPBF
- Part No.:
- LT3476EUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LT3476EUHF#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,492
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Product details
Overview
LT3476EUHF#TRPBF from Analog Devices (formerly Linear Technology) is a quad-channel, constant-current DC/DC LED driver IC with high-side current sensing, 1.5A internal NPN switches, 2.8V–16V input range, and independently PWM-controllable channels for precise color mixing and dimming in automotive, avionic, and TFT LCD backlighting systems.
For engineers reviewing the LT3476EUHF#TRPBF datasheet, LT3476EUHF#TRPBF pinout, LT3476EUHF#TRPBF application, or LT3476EUHF#TRPBF equivalent, key selection criteria include its 38-lead 5mm × 7mm QFN package, 200kHz–2MHz programmable switching frequency via RT pin, ±2.5% current sense threshold accuracy at 105mV, open-LED protection, and True Color PWM dimming supporting up to 1000:1 ratio at 100Hz.
Technical Context
The LT3476EUHF#TRPBF implements a fixed-frequency, current-mode control architecture with four independent boost/buck/buck-boost regulators. Each channel features a dedicated VADJ pin to set LED current sense threshold from 10mV to 120mV and a PWM input enabling channel-specific on/off control without affecting others.
It integrates 1.5A, 36V-rated NPN power switches and uses high-side current sensing across external sense resistors-enabling flexible topology selection and eliminating ground-referenced LED string constraints. Internal overvoltage protection clamps CAP pins at 35V (typ) to safeguard switches during open-LED faults.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 16V - supports wide-input industrial and automotive supply rails without pre-regulation |
| Max Output Current per Channel | 1.5A - enables driving high-brightness LED strings or multiple parallel LEDs per channel |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT-to-GND resistor for optimizing efficiency vs. component size |
| Current Sense Threshold Accuracy | ±2.5% at 105mV full scale - ensures tight LED current matching across all four channels |
| Dimming Ratio (PWM) | Up to 1000:1 at 100Hz - delivers smooth, flicker-free brightness control in display and lighting applications |
| Package | 38-Lead 5mm × 7mm QFN with exposed thermal pad - provides low θJC = 2°C/W for high-power LED driver thermal management |
| Operating Junction Temp | –40°C to 85°C - qualified for commercial-temperature automotive interior and avionic cabin lighting |
Pinout & Package
LT3476EUHF#TRPBF is housed in a thermally enhanced 38-lead plastic QFN (5mm × 7mm), with Pin 39 (exposed pad) electrically and thermally connected to GND and requiring soldering to PCB ground plane for proper operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC1–VC4 (Pins 1,12,13,38) | Error amplifier compensation node | Stores charge during PWM-off state to minimize transient recovery time upon re-enable |
| 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 CAP node |
| 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 >35V |
| VADJ1–VADJ4 (Pins 14,15,36,37) | LED current threshold reference | Sets full-scale sense voltage from 10mV to 120mV; direct connection to REF yields 105mV |
| PWM1–PWM4 (Pins 16,17,34,35) | Channel enable/disable control | Logic-low disables switch, reduces quiescent current, and places VC in high-Z state |
| SHDN (Pin 18) | Global shutdown input | Logic-high (>1.5V) enables device; logic-low (<0.4V) reduces supply current to <10µA |
| RT (Pin 6) | Oscillator frequency programming | Resistor to GND sets switching frequency; open or capacitive loading invalidates operation |
| VIN (Pin 33) | Main power input | Supplies internal circuitry and switch drivers; requires local 2.2µF ceramic bypass |
| GND (Pin 39) | Signal and power ground | Exposed thermal pad must be soldered to PCB ground plane for electrical integrity and thermal dissipation |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM dimming | Preserves LED chromaticity during dimming by maintaining constant current amplitude and duty-cycle modulation only |
| High-side current sensing | Enables buck, boost, or buck-boost topologies without grounding the LED cathode or anode | VADJ pin programmability | Allows precise LED current setting from 10mV to 120mV sense voltage, supporting wide dynamic range and thermal derating |
| Independent channel control | Each of four channels operates autonomously via dedicated PWM and VADJ inputs-no cross-talk or shared timing constraints |
| Open-LED protection | Detects open-circuit conditions per channel via CAP pin overvoltage clamp at 35V, preventing switch overstress in boost mode |
| Thermally enhanced QFN | 38-lead 5mm × 7mm package with exposed GND pad achieves θJC = 2°C/W for sustained 1.5A/channel operation |
Applications
| Automotive Interior Lighting | Avionic Cabin Lighting |
|---|---|
Use Scenario: Driving RGBW LED arrays in instrument clusters, ambient mood lighting, and overhead panels under 12V battery supply with wide cold-crank voltage range. IC Role / Device Role / Timing Role: Quad-channel constant-current source with independent PWM dimming per color channel to maintain white point stability and achieve >1000:1 contrast. Use Value: Eliminates need for external current-sense amplifiers and discrete MOSFET drivers while ensuring ±2.5% channel-to-channel current matching for uniform luminance. | Use Scenario: Backlighting for multifunction displays and HUDs in aircraft cockpits where EMI, reliability, and temperature resilience are critical. IC Role / Device Role / Timing Role: High-efficiency (up to 96%) quad boost converter delivering stable 1A per channel to series-connected LEDs despite 28V nominal bus fluctuations. Use Value: Integrated 35V OVP and –40°C to 85°C operation prevent field failures due to open-LED faults or thermal cycling in pressurized cabins. |
| TFT LCD Backlighting | High-Power Architectural Lighting |
Use Scenario: Driving eight-series white LED strings (up to 33V total VF) in large-format commercial displays using buck-boost topology. IC Role / Device Role / Timing Role: Four independent current-regulated outputs configured in buck-boost mode, each controlling two parallel LED strings with 100mΩ sense resistors. Use Value: Programmable 200kHz–2MHz switching frequency allows optimization for minimal EMI in noise-sensitive video signal environments. | Use Scenario: Modular LED luminaires requiring scalable, thermally robust drivers for outdoor signage and façade lighting operating from 12–24V DC supplies. IC Role / Device Role / Timing Role: Constant-current source managing four 1A LED zones with independent thermal derating via VADJ-based PTC feedback loops. Use Value: Exposed-pad QFN package enables direct mounting to aluminum heat sinks, sustaining 100W total output without forced air cooling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad-channel LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EUF#PBF | Single-channel, higher-voltage (60V) boost controller with external MOSFET drive; no integrated switches or PWM dimming | Requires external power stage and separate dimming circuitry; suited for >33V LED strings but lacks multi-channel integration | Select when driving ultra-high-VF LED arrays (>40V) where thermal density favors discrete FETs over integrated switches |
| MAX16820ATL+T | Quad-channel, 40V-rated LED driver with 1.2A max per channel, I²C interface, and built-in thermal foldback | Includes digital control and fault reporting via I²C; lower max current and no VADJ analog programming flexibility | Select when system-level microcontroller coordination, diagnostics, or automatic thermal derating are required over analog precision |
Compared with LTC3783EUF#PBF and MAX16820ATL+T, the LT3476EUHF#TRPBF uniquely combines integrated 1.5A NPN switches, analog VADJ-based current programming, and True Color PWM in a single 38-pin QFN-offering superior channel matching, simpler layout, and higher peak current capability for demanding analog-controlled lighting systems.
Availability
LT3476EUHF#TRPBF is available at Aetrix Electronics and suitable for automotive interior lighting, avionic cabin displays, and TFT LCD backlighting requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LT3476EUHF#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 acquired Linear Technology in 2017 and maintains its legacy high-performance analog product lines, including precision power management ICs for demanding industrial and automotive applications.
The LT3476EUHF#TRPBF belongs to Linear's high-current LED driver family, designed specifically for multi-channel, constant-current lighting systems requiring analog dimming fidelity, topology flexibility, and robust fault protection in safety-critical environments.
FAQ
What is the maximum LED string voltage the LT3476EUHF#TRPBF can drive in boost configuration?
The LT3476EUHF#TRPBF supports a CAP1–CAP4 operating range up to 33.5V, with internal overvoltage protection triggering at 35V (typ). In boost mode, this limits the maximum LED string forward voltage to ≤33.5V. For example, driving eight 3.6V white LEDs in series (28.8V VF) is within specification, but nine would exceed safe margin. The LT3476EUHF#TRPBF must be paired with appropriately rated external components-including Schottky diodes with ≥40V VR-to sustain reliable operation at this voltage.
Does the LT3476EUHF#TRPBF support buck, boost, and buck-boost topologies with the same pin connections?
Yes-the LT3476EUHF#TRPBF's high-side current sensing architecture enables all three topologies using identical pin assignments. In buck mode, the LED string connects between VIN and LEDn, with the sense resistor between LEDn and CAPn. In boost mode, the LED string connects between CAPn and ground, with the sense resistor between LEDn and CAPn. Buck-boost requires external inductor and diode placement per channel but reuses the same LT3476EUHF#TRPBF pin functions without modification.
How does the LT3476EUHF#TRPBF achieve 1000:1 PWM dimming ratio while maintaining color consistency?
The LT3476EUHF#TRPBF achieves 1000:1 dimming via True Color PWM, which holds LED current amplitude constant during PWM-on periods and modulates only duty cycle-preventing chromaticity shift caused by current-dependent VF changes. Its fast transient response (enabled by VC pin charge retention during PWM-off) ensures stable current settling within one switching cycle after PWM activation. This behavior is confirmed in the LT3476EUHF#TRPBF datasheet Figure TA02, showing clean 500mA square-wave LED current at 100Hz.
Can the LT3476EUHF#TRPBF operate with a 2.5V input supply?
No-the LT3476EUHF#TRPBF has a minimum specified input voltage of 2.8V per Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 2.8V risks improper biasing of internal references (REF = 1.05V), unstable oscillator function, and failure of the 1.5A NPN switches to saturate. For sub-2.8V applications, consider alternative drivers such as the LT3599 or redesign the front-end supply to meet the LT3476EUHF#TRPBF's validated 2.8V–16V operating window.
What thermal design considerations apply to the LT3476EUHF#TRPBF in continuous 1.5A/channel operation?
The LT3476EUHF#TRPBF requires soldering its exposed thermal pad (Pin 39) directly to a solid copper ground plane with ≥4 thermal vias (0.3mm diameter, spaced ≤1.2mm apart) to achieve θJC = 2°C/W. Without this, junction temperature rise exceeds safe limits: at 1.5A/channel and 16V input, power dissipation reaches ~1.8W. Layout Hints in the LT3476EUHF#TRPBF datasheet emphasize minimizing SW loop area and placing input/output capacitors adjacent to respective pins to reduce thermal hotspots and ensure long-term reliability.
LT3476EUHF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3476EUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3476EUHF#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 LT3476EUHF#TRPBF reliable?
The price and inventory of LT3476EUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3476EUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3476EUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3476EUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3476EUHF#TRPBF?
LT3476EUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3476EUHF#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 LT3476EUHF#TRPBF?
For technical support, including LT3476EUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3476EUHF#TRPBF requirements.
6.How does Aetrix verify that LT3476EUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3476EUHF#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 LT3476EUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3476EUHF#TRPBF?
All LT3476EUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3476EUHF#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 LT3476EUHF#TRPBF part is unused and in its original packaging.
Return procedure for LT3476EUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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