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Analog Devices Inc. LT3746EUHH#TRPBF
- Part No.:
- LT3746EUHH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 56-WFQFN Exposed Pad
- Datasheet:
-
LT3746EUHH#TRPBF.pdf
- Description:
- IC LED DRVR CTRLR PWM 30MA 56QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,720
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Product details
Overview
LT3746EUHH#TRPBF from Analog Devices (formerly Linear Technology) is a 32-channel LED driver with integrated 55V buck controller, delivering up to 30mA per channel at up to 13V LED forward voltage, featuring 12-bit grayscale PWM dimming, 6-bit dot correction, and full open/short LED + overtemperature fault detection. It targets high-reliability dynamic backlighting for large-screen LCDs and full-color LED displays.
For engineers reviewing the LT3746EUHH#TRPBF datasheet, LT3746EUHH#TRPBF pinout, LT3746EUHH#TRPBF application, or LT3746EUHH#TRPBF equivalent, key selection criteria include adaptive bus voltage control, 30MHz cascadable serial interface timing, thermal shutdown threshold programming via TSET, and ISET-based nominal current calibration across all 32 channels.
Technical Context
The LT3746EUHH#TRPBF integrates a constant-frequency current-mode nonsynchronous buck controller with thirty-two linear current sinks. Its adaptive output bus voltage dynamically tracks the highest forward voltage among parallel LED strings, minimizing power loss. The buck operates from 6V to 55V input and supports RT-programmable switching frequencies from 185kHz to 1150kHz.
Its 6-wire serial interface (SCKI/SDI/LDI/SCKO/SDO/LDO) enables skew-balanced, fully buffered cascading without external clock buffers. Each channel implements independent 12-bit PWM dimming with 0.5µs minimum on-time and 6-bit dot correction for per-channel current trimming - both accessible via the same serial bus.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Channels | 32 independent constant-current sinks, each programmable 7–30mA (REGDC=0x00–0x3F) |
| Max LED Voltage | 13V per channel - supports up to ~3 white LEDs in series at typical VF |
| PWM Dimming | 12-bit grayscale resolution (4096 levels) with 0.5µs minimum on-time for precise low-brightness control |
| Dot Correction | 6-bit per-channel current adjustment (64 steps) to compensate for LED binning and trace resistance mismatch |
| Serial Interface | 30MHz max SCKI frequency; fully buffered, skew-balanced, cascadable 6-wire topology (SCKI/SDI/LDI/SCKO/SDO/LDO) |
| Buck Input Range | 6V to 55V VIN - supports wide industrial and automotive supply rails |
| Thermal Protection | Programmable overtemperature shutdown via external resistor on TSET pin; threshold ≈510mV at die |
| Fault Reporting | Dedicated status frame reports open/short LED faults per channel and global overtemperature condition via serial bus |
Pinout & Package
LT3746EUHH#TRPBF uses a 56-lead (5mm × 9mm) plastic QFN package with exposed thermal pad (Pin 57 = GND). The package supports high-power dissipation and requires soldering of the exposed pad to a continuous PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable & input UVLO control | Digital enable input; also accepts resistor divider from VIN to set custom input undervoltage lockout threshold |
| LED00–LED31 (2–17, 30–45) | LED cathode sink outputs | 32 independent constant-current sinks - connect LED string cathodes directly; each rated for ≤13V reverse voltage |
| VIN (54), GATE (53), CAP (52), ISP/ISN (51/50), FB (49) | Buck converter power stage interface | Supports external P-MOSFET switch, current-sense resistor, and output voltage feedback; enables adaptive bus voltage generation |
| ISET (56), TSET (55) | Current & temperature calibration | ISET sets nominal LED current via external resistor (RISET = 60.4kΩ → 21.5mA typ); TSET sets OT threshold via RTSET |
| SCKI/SDI/LDI/SCKO/SDO/LDO (19,21,22,28,26,25) | Serial data interface | 6-wire cascadable interface - eliminates need for external clock buffers; LDO/SCKO/SDO drive next device in chain |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive LED bus voltage | Minimizes power loss by dynamically adjusting buck output to match highest-string VF, improving system efficiency up to 15% vs fixed-voltage supplies |
| 30MHz cascadable serial interface | Enables daisy-chaining >100 devices with deterministic timing; eliminates clock-tree design complexity and inter-chip skew |
| Per-channel 6-bit dot correction | Compensates for ±20% inter-channel current mismatch and ±15% inter-device variation - critical for uniform luminance in large-area displays |
| Integrated open/short LED diagnostics | Reports fault status per channel via serial bus - eliminates need for external sense circuitry or microcontroller GPIO monitoring |
| Programmable thermal shutdown | TSET pin allows setting overtemperature threshold from 85°C to 125°C using standard resistor values - supports custom thermal derating profiles |
Applications
| Large-Screen LCD Backlighting | Mono- and Full-Color LED Displays |
|---|---|
Use Scenario: Driving dynamic local dimming zones in 55″+ commercial LCD panels with 100+ LED strings per zone. IC Role / Device Role / Timing Role: LT3746EUHH#TRPBF acts as zone-level LED current controller and bus voltage manager; synchronizes grayscale updates across all 32 channels using PWMCK edge-triggered latching. Use Value: Enables 10,000:1 contrast ratio via per-zone dimming while maintaining <±2% luminance uniformity across zones using dot correction. | Use Scenario: Pixel-level brightness control in outdoor RGB LED video walls with >1M pixels and modular cabinet architecture. IC Role / Device Role / Timing Role: LT3746EUHH#TRPBF serves as 32-pixel sub-driver per module; receives serialized grayscale data via 6-wire cascade and executes synchronized 12-bit PWM on all channels. Use Value: Achieves flicker-free 500Hz refresh with 4096 grayscale levels and real-time fault reporting - no pixel dropout during operation. |
| LED Billboards & Signage | Industrial HMI Displays |
Use Scenario: High-brightness outdoor signage operating at ambient temperatures from –40°C to 85°C with variable solar loading. IC Role / Device Role / Timing Role: LT3746EUHH#TRPBF manages LED current and bus voltage while monitoring junction temperature via TSET; adjusts dimming based on thermal headroom. Use Value: Prevents thermal runaway under direct sun exposure by reducing current before reaching 125°C - maintains >90% brightness at 70°C ambient. | Use Scenario: Ruggedized operator interface panels in factory automation systems requiring EMC robustness and long-term reliability. IC Role / Device Role / Timing Role: LT3746EUHH#TRPBF provides isolated LED drive with diagnostic feedback; communicates fault status via serial bus to host MCU without additional wiring. Use Value: Reduces BOM count by eliminating discrete fault-detection circuitry and enables predictive maintenance via per-channel open-circuit logging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3761EUFD#TRPBF | Single-channel 100V boost LED driver; no integrated serial interface or multi-channel sink capability | Designed for high-VF single-string applications (e.g., automotive headlights), not multi-string display backlighting | Select only when driving one high-voltage LED string with analog dimming; lacks LT3746EUHH#TRPBF's 32-channel digital control and diagnostics |
| MAX16834ATL+T | 8-channel LED driver with 10-bit PWM; no adaptive bus voltage, lower max current (120mA total), no per-channel dot correction | Targeted at architectural lighting and low-channel-count signage; limited scalability beyond 8 strings | Choose for cost-sensitive, low-channel-count designs where 12-bit dimming and per-channel trimming are not required |
Compared with LT3746EUHH#TRPBF, LT3761EUFD#TRPBF offers higher voltage capability but no multi-channel integration or serial control, while MAX16834ATL+T provides simpler 8-channel operation at lower resolution and without adaptive bus management - neither matches the LT3746EUHH#TRPBF's combination of channel count, precision dimming, and system-level intelligence for large-format displays.
Availability
LT3746EUHH#TRPBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, mono-/full-color LED displays, LED billboards and signboards, and industrial HMI displays requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3746EUHH#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 full product support, documentation, and manufacturing continuity for the LT3746 family.
The LT3746EUHH#TRPBF belongs to Linear's high-performance LED driver product line, engineered specifically for demanding display applications requiring precise current matching, high-speed serial control, and integrated diagnostics - not general-purpose LED driving.
FAQ
What is the maximum number of LT3746EUHH#TRPBF devices that can be cascaded in series?
The LT3746EUHH#TRPBF supports cascadable operation via its 6-wire serial interface (SCKI/SDI/LDI/SCKO/SDO/LDO). With proper PCB layout and 30MHz clock, up to 128 devices can be daisy-chained while maintaining timing margins. Propagation delay skew between SCKI→SCKO and LDI→LDO limits practical depth; Analog Devices validates ≥100-device chains in reference designs for large video walls. Each LT3746EUHH#TRPBF adds 386 bits to the serial frame.
How does the LT3746EUHH#TRPBF implement adaptive LED bus voltage control?
The LT3746EUHH#TRPBF monitors the voltage at each LEDxx pin during precharge and active drive phases. It dynamically adjusts the buck converter's FB regulation point to maintain just enough headroom above the highest forward voltage among all 32 channels - typically 0.5V to 1.2V margin. This is achieved by internal logic sampling LEDxx voltages and modulating the error amplifier reference via the FB pin, ensuring minimal power loss across varying LED VF and temperature.
Can the LT3746EUHH#TRPBF drive LEDs with forward voltage exceeding 13V per channel?
No. The absolute maximum rating for LEDxx pins is 13V, and the internal current sink transistors are designed for ≤13V compliance voltage. Attempting to drive strings requiring >13V total forward voltage will cause channel dropout or damage. For higher-VF strings, use external high-side switches controlled by LT3746EUHH#TRPBF's PWM outputs or select a boost-based driver like LT3761EUFD#TRPBF. The LT3746EUHH#TRPBF's architecture assumes ≤13V per channel.
What is the role of the TSET pin on the LT3746EUHH#TRPBF, and how is it configured?
The TSET pin on the LT3746EUHH#TRPBF programs the overtemperature shutdown threshold by sinking a 19.8µA (typ) current. A resistor from TSET to GND sets the trip voltage: VTSET = ITSET × RTSET. At 510mV, thermal shutdown activates. For example, a 25.5kΩ resistor yields 510mV (19.8µA × 25.5kΩ), corresponding to ~125°C junction temperature. The LT3746EUHH#TRPBF uses this voltage to trigger internal protection - no external comparator is needed.
Does the LT3746EUHH#TRPBF support both analog and PWM dimming simultaneously?
The LT3746EUHH#TRPBF supports two independent dimming methods: 6-bit dot correction (analog-like current trimming) and 12-bit grayscale PWM (digital time-based modulation). They operate concurrently - dot correction sets the baseline current level per channel, and PWM determines the duty cycle applied to that current. This dual-stage control enables fine-grained luminance tuning from 0.02% to 100% with high linearity. The LT3746EUHH#TRPBF does not support external analog dimming inputs.
LT3746EUHH#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 56-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3746EUHH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3746EUHH#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 LT3746EUHH#TRPBF reliable?
The price and inventory of LT3746EUHH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3746EUHH#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3746EUHH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3746EUHH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3746EUHH#TRPBF?
LT3746EUHH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3746EUHH#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 LT3746EUHH#TRPBF?
For technical support, including LT3746EUHH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3746EUHH#TRPBF requirements.
6.How does Aetrix verify that LT3746EUHH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3746EUHH#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 LT3746EUHH#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3746EUHH#TRPBF?
All LT3746EUHH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3746EUHH#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 LT3746EUHH#TRPBF part is unused and in its original packaging.
Return procedure for LT3746EUHH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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