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Analog Devices Inc. LT3745IUJ#TRPBF
- Part No.:
- LT3745IUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT3745IUJ#TRPBF.pdf
- Description:
- IC LED DRVR CTRLR PWM 75MA 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,773
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Product details
Overview
LT3745IUJ#TRPBF from Analog Devices (formerly Linear Technology) is a 16-channel LED driver with integrated 55V buck controller, delivering up to 75mA per channel at 36V LED string voltage. It features 12-bit grayscale PWM dimming, 6-bit dot correction, ±3% LED current matching at 50mA, and a 30MHz cascadable serial interface. It is designed for large-screen LCD backlighting and full-color LED displays requiring precise current regulation and high-speed data chaining.
For engineers reviewing the LT3745IUJ#TRPBF datasheet, LT3745IUJ#TRPBF pinout, LT3745IUJ#TRPBF application, or LT3745IUJ#TRPBF equivalent, key selection considerations include adaptive bus voltage control, open/short LED fault reporting via serial interface, thermal protection with TSET-programmable threshold, and compatibility with TTL/CMOS microcontroller interfaces operating up to 30MHz.
Technical Context
The LT3745IUJ#TRPBF integrates a constant-frequency current-mode nonsynchronous buck controller with sixteen linear current sinks. The buck stage regulates an adaptive LED bus voltage using FB feedback and inductor current sensing via ISP/ISN pins, while each LED channel uses a precision current sink controlled by ISET and individual dot correction registers.
Its 6-wire serial interface (SCKI/SDI/LDI/SCKO/SDO/LDO) enables skew-balanced, fully buffered cascading without external clock buffers. Timing-critical operations-including 0.5µs minimum LED on-time, 12-bit PWM counting synchronized to PWMCK, and fault status readback-are implemented in hardware with deterministic propagation delays verified across temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Channels | 16 independent constant-current sinks, each programmable from 23.5mA to 77mA via ISET resistor and dot correction. |
| Buck Input Range | 6V to 55V VIN - supports wide-input industrial and automotive LED power rails. |
| Current Matching | ±3% max mismatch between channels at 50mA - ensures uniform brightness across multi-string displays. |
| PWM Dimming | 12-bit grayscale resolution (4096 levels) with 0.5µs minimum on-time - enables high-fidelity video-grade dimming. |
| Serial Interface | 30MHz SCKI clock, 6-wire cascadable topology - eliminates external clock-tree buffers and supports >100-chip daisy chains. |
| Thermal Protection | TSET pin sets overtemperature threshold via resistor; fault reported via serial status frame - enables system-level thermal management. |
| Package | 40-lead 6mm × 6mm QFN with exposed pad - provides low θJC = 2.5°C/W for high-power LED driving. |
Pinout & Package
LT3745IUJ#TRPBF is housed in a 40-lead plastic QFN package (6mm × 6mm) with exposed thermal pad (Pin 41), which must be soldered to PCB ground for thermal performance and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable & input UVLO control | Dual-function pin: digital enable (≥1.34V) or resistor-divider–programmed VIN UVLO (e.g., 4.9V threshold). |
| LED00–LED15 (2–9, 22–29) | LED cathode current sinks | 16 dedicated linear current outputs; each sinks up to 75mA with ±3% matching and individual 6-bit trim. |
| VIN (38), GATE (37), CAP (36), ISP/ISN (35/34) | Buck power stage interface | Supports external P-MOSFET switch, current-sense resistor, and VIN-referenced 6.8V gate bias (CAP). |
| ISET (40), TSET (39), FB (33) | Analog configuration inputs | ISET sets nominal current (e.g., 50mA @ 60.4kΩ); TSET programs OT threshold; FB sets adaptive bus voltage (1.205V reference). |
| SCKI/SDI/LDI/SCKO/SDO/LDO (11,13,14,20,18,17) | 6-wire serial interface | Full-duplex, skew-balanced, cascadable interface - LDO/SCKO/SDO drive next device; no global clock routing needed. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive LED bus voltage | Dynamic output regulation via FB feedback minimizes power loss across varying LED string counts and forward voltages. |
| Integrated diagnostics | Per-channel open/short LED detection and overtemperature flag reported back through serial status frame. |
| 6-wire cascadable interface | Eliminates need for external clock buffers; enables reliable >100-device daisy chains at 30MHz with matched trace routing. |
| 0.5µs minimum LED on-time | Enables high-frequency PWM dimming (e.g., 500Hz at 4096:1 ratio) without pulse truncation or brightness nonlinearity. |
| ±1% typical current matching | Reduces binning requirements and improves display uniformity without external calibration. |
Applications
| Large-Screen LCD Backlighting | Mono-Color LED Signage |
|---|---|
Use Scenario: Dynamic local dimming in 55″+ LCD TVs and commercial displays using 16 parallel LED strings per LT3745IUJ#TRPBF. IC Role / Device Role / Timing Role: Buck controller generates adaptive bus voltage; 16-channel sink provides per-zone current control and 12-bit PWM dimming synchronized to video frame timing. Use Value: Achieves >10,000:1 contrast ratio with real-time dimming updates at 60Hz via 30MHz serial interface, reducing power by 35% vs fixed-voltage supply. | Use Scenario: Outdoor monochrome LED billboards with 128×64 pixel modules driven by cascaded LT3745IUJ#TRPBF arrays. IC Role / Device Role / Timing Role: Acts as column driver with dot correction compensation for LED aging; serial interface chains 64 devices per line with sub-10ns inter-device skew. Use Value: Enables factory-set brightness uniformity across 4096 LEDs per module and runtime fault reporting without added microcontroller overhead. |
| Full-Color RGB Display Panels | Industrial HMI LED Arrays |
Use Scenario: High-refresh-rate RGB LED panels for broadcast studios, where color fidelity and flicker-free operation are critical. IC Role / Device Role / Timing Role: Drives R/G/B subpixels independently per channel; 0.5µs min on-time supports 3840Hz subfield PWM without visible artifacts. Use Value: Eliminates color breakup and motion blur in fast-moving content while maintaining 100% luminance linearity across 4096 grayscale steps. | Use Scenario: Operator interface panels in factory automation systems requiring robust LED indication under EMI-heavy environments. IC Role / Device Role / Timing Role: Provides fault-tolerant LED drive with open/short detection; thermal shutdown via TSET prevents failure during prolonged high-brightness operation. Use Value: Reduces field service calls by 70% through early fault detection and diagnostic status reporting over existing control bus. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3761EUFD#PBF | Single-channel 100V boost LED driver; no integrated LED sink array or serial interface. | Used in high-VF single-string automotive headlights; lacks multi-channel dimming or diagnostics. | Select when driving one high-voltage string (>60V) with analog dimming only. |
| MAX20050ATP/V+T | 4-channel 60V buck LED driver with I²C interface; no dot correction, lower PWM resolution (10-bit), no cascading capability. | Targeted at automotive interior lighting with AEC-Q100 qualification; lacks display-grade timing precision. | Select for automotive-qualified designs needing basic multi-channel control without display-grade grayscale or chaining. |
Compared with LT3745IUJ#TRPBF, LT3761EUFD#PBF serves single-string high-voltage needs but offers no multi-channel control or diagnostics, while MAX20050ATP/V+T provides automotive qualification and I²C simplicity at the cost of grayscale depth, cascading, and per-channel trimming-making LT3745IUJ#TRPBF uniquely suited for high-channel-count, high-fidelity display applications.
Availability
LT3745IUJ#TRPBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, mono/multi-color LED signage, full-color display panels, and industrial HMI LED arrays requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LT3745IUJ#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 high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LT3745IUJ#TRPBF belongs to Linear's high-density LED driver product line, engineered specifically for dynamic backlighting and large-format displays demanding precision current matching, high-speed serial control, and integrated fault diagnostics.
FAQ
What is the maximum LED string voltage supported per channel of the LT3745IUJ#TRPBF?
The LT3745IUJ#TRPBF supports up to 36V LED string voltage per channel, as confirmed by the "LEDxx Operating Voltage" specification (36V min) and absolute maximum rating (40V). This allows driving up to 10–12 white LEDs in series at typical forward voltage (3.0–3.6V per LED) while maintaining regulation margin and thermal headroom.
How does the LT3745IUJ#TRPBF implement open/short LED fault detection?
The LT3745IUJ#TRPBF monitors each LED channel (LED00–LED15) for open-circuit (VOPEN = 0.35V threshold) and short-circuit (VSHT = 3.7–4.1V threshold) conditions. Detected faults are latched and reported in the 194-bit serial status frame read back via SDO, enabling real-time system-level error handling without additional sense circuitry.
Can the LT3745IUJ#TRPBF operate without the serial interface enabled?
Yes - the LT3745IUJ#TRPBF defaults to all LED channels disabled after power-on-reset. With SCKI/SDI/LDI unconnected and EN/UVLO pulled high, the buck controller operates normally to generate bus voltage, but LED currents remain zero until valid serial data is clocked in. No pull-up/down resistors are required on serial pins for basic buck-only use.
What is the purpose of the CAP pin on the LT3745IUJ#TRPBF, and how must it be decoupled?
The CAP pin on the LT3745IUJ#TRPBF is the negative terminal of an internal VIN-referenced 6.8V linear regulator that powers the gate driver. It must be decoupled with a 0.47µF ceramic capacitor directly to VIN (not ground), as specified in the Typical Application schematic and Absolute Maximum Ratings table - incorrect connection risks gate drive failure or thermal runaway.
Does the LT3745IUJ#TRPBF support synchronization of multiple devices to a common clock?
Yes - the SYNC pin accepts an external TTL/CMOS clock signal (200kHz–1MHz) to synchronize the internal oscillator across multiple LT3745IUJ#TRPBF devices. This eliminates beat frequencies and EMI peaks in multi-chip LED systems, and is required for coherent PWM dimming across physically separated display zones.
LT3745IUJ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-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:
- 16
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 55V
- Voltage - Output:
- 36V
- Current - Output / Channel:
- 75mA
- Frequency:
- 200kHz ~ 1MHz
- Dimming:
- PWM
- Applications:
- Backlight, Signage
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (6x6)
LT3745IUJ#TRPBF FAQ
1.How can I place an order for LT3745IUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3745IUJ#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 LT3745IUJ#TRPBF reliable?
The price and inventory of LT3745IUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3745IUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3745IUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3745IUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3745IUJ#TRPBF?
LT3745IUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3745IUJ#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 LT3745IUJ#TRPBF?
For technical support, including LT3745IUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3745IUJ#TRPBF requirements.
6.How does Aetrix verify that LT3745IUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3745IUJ#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 LT3745IUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3745IUJ#TRPBF?
All LT3745IUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3745IUJ#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 LT3745IUJ#TRPBF part is unused and in its original packaging.
Return procedure for LT3745IUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3745IUJ#TRPBF Tags
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