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Analog Devices Inc. LT3476IUHF#PBF
- Part No.:
- LT3476IUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LT3476IUHF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:264
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Product details
Overview
LT3476IUHF#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 TFT LCD backlighting and avionic lighting systems.
For engineers reviewing the LT3476IUHF#PBF datasheet, LT3476IUHF#PBF pinout, LT3476IUHF#PBF application, or LT3476IUHF#PBF equivalent, key selection criteria include its –40°C to 125°C operating junction temperature, 38-lead 5mm × 7mm QFN package with exposed thermal pad, 200kHz–2MHz programmable switching frequency, and True Color PWM dimming supporting up to 1000:1 ratio at 100Hz.
Technical Context
The LT3476IUHF#PBF implements a fixed-frequency, current-mode control architecture with four independent channels, each featuring an internal 1.5A/36V NPN power switch and high-side current sensing via external sense resistors. Each channel's regulation threshold is trimmed to ±2.5% at 105mV full scale, and VADJ pins allow precise adjustment of the sense threshold from 10mV to 120mV.
It integrates open-LED protection with 35V overvoltage clamp per CAP pin, thermally enhanced 38-lead QFN packaging, and independent shutdown (SHDN) and PWM inputs per channel. The RT pin enables oscillator frequency programming, while REF provides a stable 1.05V reference for VADJ biasing and compensation network design.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.8V to 16V - supports wide-input industrial and automotive battery rails without pre-regulation. |
| Max Output Current per Channel | 1.5A - enables driving high-brightness LED strings in backlight and illumination applications. |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT resistor to balance efficiency vs. component size and EMI. |
| Current Sense Threshold Accuracy | ±2.5% at 105mV - ensures tight LED current matching across all four channels. |
| Junction Temp Range | –40°C to 125°C - qualified for under-hood automotive and avionic environments. |
| Package | 38-Lead 5mm × 7mm QFN with exposed GND pad - provides low thermal resistance (θJC = 2°C/W) for high-power LED driving. |
| Dimming Ratio | 1000:1 (PWM), up to 5000:1 (True Color PWM in boost) - enables precise color mixing and flicker-free dimming. |
| Shutdown Current | <10µA - minimizes system standby power in always-on lighting control modules. |
Pinout & Package
LT3476IUHF#PBF uses a thermally enhanced 38-lead plastic QFN package (5mm × 7mm) with exposed GND pad (Pin 39) that must be soldered to PCB ground plane for electrical integrity and thermal performance (θJA = 34°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC1–VC4 (Pins 1,12,13,38) | Error amplifier compensation node | Stores charge during PWM off-time to minimize transient recovery; requires external RC network for loop stability. |
| 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 voltage. |
| CAP1–CAP4 (Pins 3,4,9,10) | Inverting current sense input | Connects to low-side of sense resistor and output filter capacitor; triggers OVP clamp at 35V. |
| VADJ1–VADJ4 (Pins 14,15,36,37) | Current threshold programming input | Sets full-scale sense voltage from 10mV to 120mV; direct connection to REF yields 105mV. |
| PWM1–PWM4 (Pins 16,17,34,35) | Channel enable/dimming control | Logic-low disables switch, reduces quiescent current, and places VC in high-Z state to retain compensation charge. |
| SHDN (Pin 18) | Global device enable | Logic-high (>1.5V) activates all channels; logic-low (<0.4V) forces full shutdown <10µA. |
| RT (Pin 6) | Oscillator frequency set | Resistor-to-GND sets switching frequency; 21kΩ yields ~1MHz, 8.25kΩ yields ~2MHz. |
| REF (Pin 7) | Internal 1.05V reference output | Stable reference for VADJ biasing and external DAC interfacing; bypass with 0.1µF ceramic capacitor. |
| VIN (Pin 33) | Main power input | Supplies internal circuitry and gate drive; requires local 2.2µF ceramic bypass close to pin. |
| GND (Pin 39) | Signal & power ground | Exposed thermal pad - must be soldered to PCB ground plane for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Four independent 1.5A NPN switches | Enables simultaneous, isolated control of four LED strings without cross-channel interference. |
| High-side current sensing | Supports buck, boost, and buck-boost configurations with flexible LED string placement and grounding. |
| True Color PWM dimming | Maintains consistent LED chromaticity across 1000:1 dimming range by preserving analog current regulation during PWM on-cycles. |
| VADJ-adjustable current threshold (10–120mV) | Allows precise LED current tuning per channel using resistor dividers or DACs without changing sense resistors. |
| Per-channel open-LED protection | Independent 35V overvoltage clamp on each CAP pin prevents switch failure during LED string disconnect or open-circuit faults. |
| Thermally enhanced QFN package | 38-lead 5mm × 7mm QFN with exposed GND pad achieves θJC = 2°C/W for sustained 1A/channel operation. |
Applications
| Automotive Instrument Cluster Backlighting | TFT LCD Cockpit Display Lighting |
|---|---|
Use Scenario: Driving multiple white LED strings behind segmented LCD panels in vehicle dashboards with variable ambient light conditions. IC Role / Device Role / Timing Role: Quad-channel constant-current source with independent PWM dimming per string to maintain uniform brightness and color fidelity across temperature and supply variations. Use Value: Enables seamless transition between day/night modes with 1000:1 dimming ratio and eliminates visible flicker at 100Hz PWM frequency. | Use Scenario: Powering high-resolution avionic-grade TFT displays requiring precise luminance control and fault tolerance in flight deck environments. IC Role / Device Role / Timing Role: High-reliability LED driver with –40°C to 125°C operation, per-channel open-LED detection, and robust EMI suppression via optimized SW layout. Use Value: Ensures uninterrupted display operation during LED failure events and meets DO-160E conducted/radiated emissions requirements. |
| RGB LED Color Mixing Module | Industrial Panel PC Backlight System |
Use Scenario: Controlling red, green, and blue LED strings in medical imaging UIs where accurate color rendering and smooth intensity ramping are critical. IC Role / Device Role / Timing Role: Independent current regulation and synchronized PWM dimming across three channels to achieve stable white point and calibrated gamma curves. Use Value: Delivers ≤2.5% current matching between channels and supports True Color PWM for >5000:1 effective dimming in boost configuration. | Use Scenario: Driving 8-LED-per-string backlight arrays in factory automation HMIs exposed to vibration, dust, and wide temperature swings. IC Role / Device Role / Timing Role: Four-channel 1A driver with buck-boost topology flexibility and thermal management via exposed QFN pad for continuous 24/7 operation. Use Value: Eliminates need for external current-sense amplifiers and reduces BOM count while maintaining ±2% LED current accuracy over life. |
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 |
|---|---|---|---|
| LT3476EUHF#PBF | Same silicon, rated for –40°C to 85°C junction temperature; lower max operating temp than LT3476IUHF#PBF. | Suitable for commercial/industrial indoor lighting but not under-hood automotive or avionics. | Select LT3476EUHF#PBF only if ambient temperature stays below 85°C and extended temp qualification is unnecessary. |
| LT3599EFE#PBF | Quad-channel 40V LED driver with integrated 1.1A MOSFETs; no VADJ pin; fixed 100mV sense threshold. | Lacks per-channel current threshold adjustability and True Color PWM; supports higher output voltage (40V vs 36V). | Choose LT3599EFE#PBF when simpler design, higher output voltage, and lower cost outweigh need for fine-grained current tuning. |
Compared with LT3476EUHF#PBF, the LT3476IUHF#PBF offers extended temperature reliability for harsh environments, while LT3599EFE#PBF trades programmability for higher integration and voltage headroom-making LT3476IUHF#PBF optimal for precision, multi-zone automotive lighting where thermal margin and dimming fidelity are critical.
Availability
LT3476IUHF#PBF is available at Aetrix Electronics and suitable for automotive instrument clusters, avionic cockpit displays, RGB color-mixing modules, and industrial panel PC backlighting requiring stable component supply across extended temperature ranges.
Supply support for LT3476IUHF#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 full product support, documentation, and manufacturing continuity for legacy Linear parts including the LT3476 series.
The LT3476 product line was designed specifically for high-reliability, multi-string LED lighting in automotive, aerospace, and industrial human-machine interfaces where precise current regulation, thermal resilience, and fault tolerance are mandatory.
FAQ
What is the maximum operating junction temperature for LT3476IUHF#PBF?
The LT3476IUHF#PBF is guaranteed to operate continuously from –40°C to 125°C junction temperature. Its thermal design-featuring a 38-lead QFN with exposed GND pad (θJC = 2°C/W)-enables reliable 1A/channel operation in automotive under-hood and avionic environments where ambient temperatures exceed 85°C. Exceeding 125°C triggers internal thermal shutdown.
How does LT3476IUHF#PBF implement high-side current sensing?
The LT3476IUHF#PBF senses current at the high side of the LED string using dedicated LEDn and CAPn pins per channel. It regulates the voltage difference between them to 0.1×VADJ, enabling buck, boost, or buck-boost topologies without grounding constraints. This architecture avoids ground-loop issues and allows flexible LED string placement while maintaining ±2.5% current accuracy at full scale.
Can LT3476IUHF#PBF drive more than one LED per channel?
Yes, the LT3476IUHF#PBF can drive multiple LEDs in series per channel-up to 8 LEDs as shown in typical applications-provided the total forward voltage remains within the 33.5V CAP/LED operating range and the external sense resistor and inductor are sized accordingly. Its 36V-rated internal NPN switch and 35V overvoltage clamp ensure safe operation with common white LED strings (VF ≈ 3.6V @ 1A).
What is the role of the VADJ pin in LT3476IUHF#PBF?
The VADJ pin on LT3476IUHF#PBF sets the full-scale current sense threshold from 10mV to 120mV, directly scaling the regulated LED current. Connecting it to the internal 1.05V REF yields 105mV (1A with 100mΩ resistor); using a resistor divider or DAC enables precise per-channel current tuning without changing hardware. VADJ must never float or exceed 1.25V to avoid unintended 125mV default threshold.
Does LT3476IUHF#PBF support synchronization to an external clock?
No, the LT3476IUHF#PBF does not support external clock synchronization. Its switching frequency is set solely by the RT pin resistor (200kHz–2MHz), and the oscillator is free-running. For systems requiring phase-aligned switching across multiple LT3476IUHF#PBF devices, external timing coordination must be implemented at the PWM control level-not at the switching frequency level.
LT3476IUHF#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 ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LT3476IUHF#PBF FAQ
1.How can I place an order for LT3476IUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3476IUHF#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 LT3476IUHF#PBF reliable?
The price and inventory of LT3476IUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3476IUHF#PBF is usually 5 days.
3.What payment methods are accepted for LT3476IUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3476IUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3476IUHF#PBF?
LT3476IUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3476IUHF#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 LT3476IUHF#PBF?
For technical support, including LT3476IUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3476IUHF#PBF requirements.
6.How does Aetrix verify that LT3476IUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3476IUHF#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 LT3476IUHF#PBF meets industry standards.
7.What is the process for return or replacement of LT3476IUHF#PBF?
All LT3476IUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3476IUHF#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 LT3476IUHF#PBF part is unused and in its original packaging.
Return procedure for LT3476IUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3476IUHF#PBF Tags
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