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Analog Devices Inc. LT3476IUHF#TRPBF
- Part No.:
- LT3476IUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LT3476IUHF#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,403
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Product details
Overview
LT3476IUHF#TRPBF 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, 200kHz–2MHz programmable switching frequency, and independent PWM dimming per channel. It operates from 2.8V to 16V input and delivers up to 1A per channel in buck, boost, or buck-boost configurations for automotive lighting and TFT LCD backlighting.
For engineers reviewing the LT3476IUHF#TRPBF datasheet, LT3476IUHF#TRPBF pinout, LT3476IUHF#TRPBF application, or LT3476IUHF#TRPBF equivalent, key selection criteria include its –40°C to 125°C industrial temperature grade, 38-lead 5mm × 7mm QFN package with exposed thermal pad, 105mV full-scale current sense threshold accuracy (±2.5%), True Color PWM dimming up to 1000:1 (100Hz), and open-LED protection with 35V overvoltage clamp.
Technical Context
The LT3476IUHF#TRPBF implements a fixed-frequency, current-mode control architecture with four independent switching regulators. Each channel features a dedicated VADJ pin to set the LED current sense threshold from 10mV to 120mV, and a PWM input that disables switching while preserving VC compensation state for fast transient recovery.
It uses high-side current sensing across external sense resistors, enabling flexible topology support. The RT pin programs oscillator frequency via an external resistor; internal 1.05V REF output drives VADJ pins directly or through dividers; and each SW pin integrates a 1.5A/36V NPN switch with 350mV VCE(SAT) at 1.3A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 16V - supports wide automotive battery range and regulated 3.3V/5V rails. |
| Max Output Current per Channel | 1.5A - enables driving high-brightness LED strings without external switches. |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT resistor to balance efficiency vs. component size. |
| Current Sense Threshold Accuracy | ±2.5% at 105mV - ensures precise, stable LED current regulation across temperature. |
| Junction Temp Range | –40°C to 125°C - qualified for under-hood automotive and avionic environments. |
| Dimming Ratio (PWM) | 1000:1 at 100Hz - enables fine-grained brightness control without color shift. |
| Overvoltage Protection | 35V clamp on CAP pins - prevents switch damage during LED open-circuit faults. |
| Shutdown Current | <10µA - minimizes system standby power loss. |
Pinout & Package
LT3476IUHF#TRPBF is housed in a thermally enhanced 38-lead plastic QFN package (5mm × 7mm) with exposed GND pad (Pin 39) requiring PCB soldering for electrical and thermal integrity.
| 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 dimming transient recovery delay. |
| LED1–LED4 (Pins 2,5,8,11) | Non-inverting current sense input | Connects to high-side of external sense resistor; regulated to VCAP − 0.1·VADJ. |
| 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) | Current threshold programming input | Sets full-scale sense voltage from 10mV to 120mV; 1.05V REF connection 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 all channels; logic-low (<0.4V) disables entire device. |
| RT (Pin 6) | Oscillator frequency programming | Resistor to GND sets switching frequency; 21kΩ yields ~1MHz typical operation. |
| REF (Pin 7) | Internal 1.05V reference output | Stable, low-drift reference for VADJ biasing or external DAC interfacing. |
| VIN (Pin 33) | Main power supply input | Accepts 2.8V–16V; requires local 1µF+ ceramic bypass capacitor. |
| GND (Pin 39) | Signal and power ground | Exposed thermal pad must be soldered to PCB ground plane for thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM dimming | Preserves LED chromaticity during 1000:1 dimming by maintaining constant peak current per cycle. |
| High-side current sensing | Enables buck, boost, and buck-boost topologies without ground-referenced LED strings. | Independent channel control | Four fully isolated PWM inputs allow individual color mixing or brightness adjustment per LED string. |
| VADJ-programmable current threshold | Adjusts full-scale sense voltage from 10mV to 120mV, supporting 10mΩ–120mΩ sense resistors. |
| Open-LED protection | Per-channel 35V overvoltage lockout prevents switch failure when LED strings disconnect. |
| Thermally enhanced QFN | 38-lead 5mm × 7mm package with exposed pad achieves θJA = 34°C/W for high-power LED driving. |
Applications
| Automotive Headlamp Control | TFT LCD Backlight Driver |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with independently controlled high-beam LED segments. IC Role / Device Role / Timing Role: Quad-channel constant-current source regulating four LED strings with synchronized PWM dimming for beam shaping. Use Value: Enables dynamic light distribution without mechanical actuators, leveraging 1000:1 dimming ratio and –40°C to 125°C operation. | Use Scenario: High-brightness backlight for 10.1″ automotive infotainment display with local dimming zones. IC Role / Device Role / Timing Role: Four-channel LED driver powering parallel white LED strings in boost configuration with independent brightness control. Use Value: Delivers uniform luminance across display using high-side sensing and 2.5% current matching between channels. |
| Avionic Cabin Lighting | Industrial Machine Vision Illumination |
Use Scenario: RGBW cabin lighting system requiring flicker-free, calibrated color mixing in aircraft interiors. IC Role / Device Role / Timing Role: Constant-current driver for red, green, blue, and white LED strings with independent VADJ and PWM control per channel. Use Value: Achieves precise color point stability via 105mV sense threshold accuracy and True Color PWM, meeting DO-160 environmental requirements. | Use Scenario: High-intensity strobed illumination for barcode readers and automated optical inspection systems. IC Role / Device Role / Timing Role: Fast-response LED driver delivering pulsed 1A currents with sub-microsecond PWM edge timing. Use Value: Supports high-speed imaging with minimal motion blur using 1.5A internal switches and <10µA shutdown current for duty-cycled operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Single-channel, higher-voltage (60V) boost controller; no integrated switch; requires external MOSFET. | Used in high-output-voltage LED arrays where >36V compliance is needed; lacks quad integration. | Select when designing custom high-efficiency boost stages with >36V LED strings and need flexibility in switch selection. |
| MAX16820ATL+ | Quad-channel, but only 350mA max per channel; 16V max input; no VADJ programmability - fixed 100mV threshold. | Suitable for lower-power indicator lighting; lacks automotive temp grade and True Color PWM. | Choose for cost-sensitive, non-automotive applications requiring basic quad dimming below 350mA/channel. |
Compared with LTC3783EFE#PBF and MAX16820ATL+, the LT3476IUHF#TRPBF uniquely combines quad 1.5A channels, –40°C to 125°C rating, VADJ-adjustable current threshold, and True Color PWM in a single QFN package-enabling compact, high-reliability lighting designs without external power switches or complex compensation.
Availability
LT3476IUHF#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp control, avionic cabin lighting, TFT LCD backlighting, industrial machine vision illumination, and high-reliability LED signage requiring stable component supply across extended temperature ranges.
Supply support for LT3476IUHF#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, Inc. (ADI) 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 LT3476IUHF#TRPBF belongs to Linear's high-current LED driver family, designed specifically for robust, multi-string LED lighting in safety-critical environments where thermal resilience, channel independence, and fault protection are mandatory.
FAQ
What is the maximum LED string voltage supported by the LT3476IUHF#TRPBF?
The LT3476IUHF#TRPBF supports up to 33.5V across its CAP1–CAP4 pins in normal operation, with overvoltage lockout triggering at 35V (typical). This allows driving LED strings totaling ~9–10 white LEDs (VF ≈ 3.6V) in boost configuration while maintaining safe switch operation and open-circuit protection. The internal 36V-rated NPN switches ensure margin against transients.
Does the LT3476IUHF#TRPBF support buck, boost, and buck-boost topologies?
Yes, the LT3476IUHF#TRPBF supports all three topologies due to its high-side current sensing architecture. Unlike low-side sensing drivers, it regulates current regardless of whether the LED string is connected between CAP and ground (buck), between VIN and SW (boost), or in more complex buck-boost arrangements - confirmed in the datasheet's Typical Application circuits and Pin Functions section.
How does the VADJ pin affect LED current programming in the LT3476IUHF#TRPBF?
The VADJ pin sets the full-scale current sense threshold across the external sense resistor. With REF (1.05V) applied, VADJ = 1.05V yields a 105mV threshold; scaling VADJ down to 100mV gives 100mV threshold. The relationship is linear: ILED = VADJ/10/RSENSE. This allows precise current setting from ~10mA to >1A using standard resistor values, as verified in the Electrical Characteristics table and Applications Information section.
What thermal management is required for the LT3476IUHF#TRPBF in continuous 1A operation?
The LT3476IUHF#TRPBF requires soldering its exposed thermal pad (Pin 39) to a minimum 200mm² copper area on the PCB to achieve θJA = 34°C/W. At 1A per channel and 16V input, power dissipation can exceed 2W; without adequate copper pour and vias to inner ground planes, junction temperature may exceed 125°C. Layout Hints in the datasheet explicitly mandate this for reliable operation.
Can the LT3476IUHF#TRPBF achieve dimming ratios beyond 1000:1?
Yes - the LT3476IUHF#TRPBF achieves up to 5000:1 dimming ratio in boost configuration using True Color PWM, as stated in the Features list. However, the guaranteed 1000:1 ratio applies to general operation (including buck and buck-boost); achieving 5000:1 requires optimized layout, stable 100Hz PWM timing, and adherence to minimum on/off time guidelines (≥10 switching cycles) per the Applications Information section.
LT3476IUHF#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 ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LT3476IUHF#TRPBF FAQ
1.How can I place an order for LT3476IUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3476IUHF#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 LT3476IUHF#TRPBF reliable?
The price and inventory of LT3476IUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3476IUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3476IUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3476IUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3476IUHF#TRPBF?
LT3476IUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3476IUHF#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 LT3476IUHF#TRPBF?
For technical support, including LT3476IUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3476IUHF#TRPBF requirements.
6.How does Aetrix verify that LT3476IUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3476IUHF#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 LT3476IUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3476IUHF#TRPBF?
All LT3476IUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3476IUHF#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 LT3476IUHF#TRPBF part is unused and in its original packaging.
Return procedure for LT3476IUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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