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Analog Devices Inc. LT3746EUHH#PBF
- Part No.:
- LT3746EUHH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 56-WFQFN Exposed Pad
- Datasheet:
-
LT3746EUHH#PBF.pdf
- Description:
- IC LED DRVR CTRLR PWM 30MA 56QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,490
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Product details
Overview
LT3746EUHH#PBF from Analog Devices (formerly Linear Technology) is a 32-channel constant-current LED driver with integrated 55V buck controller, designed for high-efficiency adaptive LED bus voltage generation in large-format displays. It delivers up to 30mA per channel at ≤13V LED forward voltage, supports 12-bit grayscale PWM dimming at 500Hz, and features 6-bit per-channel dot correction. It is used in dynamic LCD backlighting and full-color LED signage requiring precise current matching and fault diagnostics.
For engineers reviewing the LT3746EUHH#PBF datasheet, LT3746EUHH#PBF pinout, LT3746EUHH#PBF application, or LT3746EUHH#PBF equivalent, key selection criteria include its 32-channel independent sink architecture, 30MHz cascadable serial interface, open/short LED and overtemperature protection reporting, and compatibility with P-channel MOSFET gate drive for buck-stage control.
Technical Context
The LT3746EUHH#PBF integrates a current-mode nonsynchronous buck controller with thirty-two linear current sinks. The buck stage regulates an adaptive output bus voltage (via FB feedback) to match the highest forward voltage among parallel LED strings, minimizing power loss. Each sink channel uses internal current mirrors referenced to ISET, with per-channel 6-bit digital trim and 12-bit PWM timing controlled via TTL/CMOS serial interface.
Its 6-wire serial interface (SCKI/SDI/LDI/SCKO/SDO/LDO) enables skew-balanced, fully buffered cascading without external clock buffers - critical for synchronized grayscale updates across hundreds of channels in video-grade displays. Fault status (open/short LED, overtemperature) is reported back through the same interface in real time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Channels | 32 independent constant-current sinks, each programmable 7–30mA (REGDC = 0x00–0x3F), enabling uniform brightness across large LED arrays. |
| Buck Input Range | 6V to 55V VIN, supporting wide-input industrial and automotive display power rails without pre-regulation. |
| Dimming Resolution | 12-bit grayscale PWM (4096 steps) with 0.5µs minimum on-time, enabling smooth, flicker-free dimming down to 0.024% duty cycle at 500Hz. |
| Serial Interface Speed | 30MHz SCKI clock, enabling full 386-bit frame load in ≤13µs - sufficient for real-time video-rate updates in multi-chip cascades. |
| Current Matching | ±8% max mismatch between channels (ΔILEDC), ensuring <±0.25% luminance variation across 32 LEDs under matched thermal conditions. |
| Fault Diagnostics | Dedicated per-channel open/short detection (VOPEN = 0.1V, VSHT = 3.9V threshold) and TSET-programmable overtemperature shutdown with status reporting. |
| Package | 56-lead 5mm × 9mm plastic QFN (UHH), exposed pad soldered to PCB ground for thermal dissipation (θJC = 2.0°C/W). |
Pinout & Package
LT3746EUHH#PBF is housed in a 56-lead (5mm × 9mm) plastic QFN package (UHH) with exposed thermal pad (Pin 57 = GND). Pin numbering follows top-view layout with pins 1–17, 30–45 assigned to LED outputs; critical control pins include ISET (Pin 56), TSET (Pin 55), FB (Pin 49), and the 6-wire serial interface (SCKI/Pin 19, SDI/Pin 21, LDI/Pin 22, SCKO/Pin 28, SDO/Pin 26, LDO/Pin 25).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LED00–LED31 (Pins 2–17, 30–45) | Constant-current sink outputs | Each drives LED string cathode; supports ≤13V reverse voltage and 30mA max sink current with 6-bit digital trim. |
| ISET (Pin 56) | Nominal current reference input | Resistor-to-ground sets average LED current (e.g., 60.4kΩ → 21.5mA typical); VISET = 1.205V ±0.024V over temp. |
| TSET (Pin 55) | Overtemperature threshold programming | Resistor-to-ground sets junction trip point (e.g., 100kΩ → ~115°C); ITSET = 19.8µA ±0.8µA defines threshold voltage. |
| FB (Pin 49) | Buck output voltage regulation sense | Connected to resistor divider from VOUT; regulates to 1.205V reference, enabling adaptive bus voltage tracking of LED string Vf. |
| SCKI/SDI/LDI (Pins 19/21/22) | Serial command input | TTL/CMOS-compatible inputs accepting 30MHz clock, data, and latch signals; enable frame-based GS/DC register loading. |
| SCKO/SDO/LDO (Pins 28/26/25) | Serial cascade outputs | Skew-matched outputs driving next device in chain; eliminate need for external clock buffers in multi-chip systems. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive LED bus voltage | Reduces power loss by dynamically adjusting buck output to match the highest-string forward voltage - improves efficiency up to 15% vs fixed-bus designs. |
| 30MHz cascadable serial interface | Enables daisy-chaining >100 devices with deterministic timing; eliminates clock-tree design complexity and inter-chip skew in large displays. |
| Per-channel 6-bit dot correction | Compensates for LED binning and PCB trace resistance variations, achieving <±1% luminance uniformity across 32 channels after calibration. |
| Real-time fault reporting | Open/short LED and overtemperature status bits (S0–S31, F0) shift out on SDO during every frame - enables rapid system-level diagnostics without polling. |
| P-channel MOSFET gate driver | GATE pin delivers ±1A peak current with 30ns rise/fall times, directly driving high-side switches without external drivers in buck topology. |
Applications
| Large-Screen LCD Backlighting | Mono-Color LED Billboards |
|---|---|
|
Use Scenario: Dynamic local dimming in 65"+ commercial LCD panels using 32-zone parallel LED strings. IC Role / Device Role / Timing Role: LT3746EUHH#PBF acts as zone controller - buck stage supplies adaptive bus voltage while 32 sinks modulate individual zones at 500Hz PWM. Use Value: Enables >10,000:1 contrast ratio via per-zone dimming, with 0.5µs minimum on-time preventing visible PWM artifacts at low brightness. |
Use Scenario: Outdoor monochrome signage with 128×32 LED matrix driven by eight LT3746EUHH#PBF in cascade. IC Role / Device Role / Timing Role: LT3746EUHH#PBF serves as column driver - each IC controls 32 columns; 30MHz serial interface synchronizes full-frame updates in <100µs. Use Value: Eliminates external clock buffers and reduces PCB layer count by 2 vs 4-wire alternatives, lowering BOM cost and layout risk. |
| Full-Color Video Walls | Multi-Color Architectural Lighting |
|
Use Scenario: 4K-resolution LED video wall with RGB pixel pitch requiring independent current control per color sub-pixel. IC Role / Device Role / Timing Role: LT3746EUHH#PBF manages one color per chip (e.g., R/G/B per IC); 12-bit grayscale ensures >4000 intensity levels per channel. Use Value: 6-bit dot correction compensates for LED Vf drift across temperature, maintaining white-point stability over –40°C to 125°C ambient. |
Use Scenario: Tunable-white architectural lighting system with separate warm/cool white LED strings per fixture. IC Role / Device Role / Timing Role: LT3746EUHH#PBF regulates current in dual-channel mode - one set of 16 sinks for warm white, another for cool white. Use Value: Integrated open/short detection prevents single-LED failure from disabling entire string, improving field reliability in inaccessible installations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL97682IRTZ-T7A | 16-channel, 40V max, no integrated buck controller; requires external DC-DC supply. | Limited to fixed-voltage LED systems; lacks adaptive bus voltage and open/short diagnostics. | Select when board space is constrained and bus voltage is stable; not suitable for dynamic backlighting. |
| MAX20051ATPA/VY+ | Single-channel 60V buck LED driver with analog dimming only; no multi-channel or serial interface. | Designed for automotive headlamp modules, not display applications requiring pixel-level control. | Choose for high-reliability automotive LED lighting where AEC-Q100 qualification is mandatory. |
Compared with ISL97682IRTZ-T7A and MAX20051ATPA/VY+, the LT3746EUHH#PBF uniquely combines 32-channel current sinking, integrated adaptive buck control, and a 30MHz cascadable interface - making it irreplaceable for large-format video displays requiring synchronized, fault-aware, high-resolution dimming.
Availability
LT3746EUHH#PBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, full-color LED video walls, outdoor signage, and tunable-white architectural lighting requiring stable component supply and long-term production continuity.
Supply support for LT3746EUHH#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 IC portfolio, focusing on precision power management, signal conditioning, and interface solutions for demanding industrial and automotive applications.
The LT3746EUHH#PBF belongs to Linear's LED driver product line, engineered specifically for high-channel-count, high-speed display applications where adaptive voltage regulation, per-pixel current control, and robust fault reporting are essential.
FAQ
What is the maximum LED forward voltage supported per channel of the LT3746EUHH#PBF?
The LT3746EUHH#PBF supports up to 13V LED forward voltage per channel (LED00–LED31), verified by absolute maximum rating of 13V on these pins and operational validation at 13V with 30mA sink current. This enables driving 3–4 standard white LEDs in series per channel without external level-shifting circuitry.
Does the LT3746EUHH#PBF require an external microcontroller to operate?
No - the LT3746EUHH#PBF operates autonomously once configured: the buck controller starts switching after UVLO clearance and soft-start completion, and LED currents are set by ISET resistor. However, a microcontroller is required to load grayscale and dot correction data via the 30MHz serial interface for dynamic dimming and calibration.
How does the LT3746EUHH#PBF implement open/short LED detection?
The LT3746EUHH#PBF monitors each LEDxx pin voltage during active sink operation. An open LED is detected when voltage falls below 0.1V (VOPEN), and a short is flagged when voltage rises above 3.9V (VSHT). These fault states are latched and reported in the status register (S0–S31), accessible via SDO during serial readback.
Can the LT3746EUHH#PBF drive both high-side and low-side LED configurations?
The LT3746EUHH#PBF is designed exclusively for low-side (cathode-connected) LED driving: LED00–LED31 are constant-current sinks tied to GND internally. It cannot drive high-side (anode-connected) configurations. The integrated buck controller's GATE pin drives an external P-channel MOSFET for high-side switching in the power stage.
What thermal management requirements apply to the LT3746EUHH#PBF in continuous operation?
The LT3746EUHH#PBF requires soldering of its exposed pad (Pin 57) to a solid copper ground plane to achieve θJC = 2.0°C/W. At full 32-channel 30mA operation with 12V LED drop, junction temperature must be kept ≤125°C using ≥4 cm² of 2-oz copper; thermal shutdown triggers at ~115°C (TSET-dependent) to prevent damage.
LT3746EUHH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 56-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Step-Down (Buck)
- Internal Switch(s):
- No
- Number of Outputs:
- 32
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 55V
- Voltage - Output:
- -
- Current - Output / Channel:
- 30mA
- Frequency:
- 205Hz ~ 1.05MHz
- Dimming:
- PWM
- Applications:
- Backlight, Signage
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 56-QFN (5x9)
LT3746EUHH#PBF FAQ
1.How can I place an order for LT3746EUHH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3746EUHH#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 LT3746EUHH#PBF reliable?
The price and inventory of LT3746EUHH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3746EUHH#PBF is usually 5 days.
3.What payment methods are accepted for LT3746EUHH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3746EUHH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3746EUHH#PBF?
LT3746EUHH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3746EUHH#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 LT3746EUHH#PBF?
For technical support, including LT3746EUHH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3746EUHH#PBF requirements.
6.How does Aetrix verify that LT3746EUHH#PBF is sourced from the original manufacturer or authorized distributors?
All LT3746EUHH#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 LT3746EUHH#PBF meets industry standards.
7.What is the process for return or replacement of LT3746EUHH#PBF?
All LT3746EUHH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3746EUHH#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 LT3746EUHH#PBF part is unused and in its original packaging.
Return procedure for LT3746EUHH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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