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Analog Devices Inc. LT3745EUJ#TRPBF
- Part No.:
- LT3745EUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT3745EUJ#TRPBF.pdf
- Description:
- IC LED DRVR CTRLR PWM 75MA 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,726
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Product details
Overview
LT3745EUJ#TRPBF from Analog Devices (formerly Linear Technology) is a 16-channel, 50mA constant-current LED driver with integrated 55V buck controller for adaptive LED bus voltage generation. It delivers ±3% LED current matching at 50mA per channel, supports 12-bit grayscale PWM dimming up to 500Hz, and features a 30MHz cascadable serial interface. It is designed for high-precision dynamic backlighting in large-screen LCDs.
For engineers reviewing the LT3745EUJ#TRPBF datasheet, LT3745EUJ#TRPBF pinout, LT3745EUJ#TRPBF application, or LT3745EUJ#TRPBF equivalent, key selection criteria include its 40-lead 6mm × 6mm QFN package, ±1% typical current mismatch, 0.5µs minimum LED on-time, and full open/short LED + overtemperature diagnostics communicated via serial interface.
Technical Context
The LT3745EUJ#TRPBF integrates a current-mode nonsynchronous buck controller with sixteen linear current sinks. The buck stage regulates an adaptive output bus voltage (via FB pin and external resistor divider), while each LED channel uses independent 6-bit dot correction and 12-bit PWM registers accessible through a 6-wire TTL/CMOS serial interface (SCKI/SDI/LDI/SCKO/SDO/LDO).
Its internal architecture includes a 1.205V reference for FB regulation, a programmable RT-based oscillator (200kHz–1MHz), and thermal shutdown triggered by TSET-pin resistor programming. Fault status-including per-channel open/short LED and overtemperature-is latched and shifted out via the SDO line during status-frame reads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 6V to 55V input - supports wide-range industrial and display power rails without pre-regulation. |
| LED Current per Channel | 25mA to 75mA (typ 50mA) - set by ISET resistor; enables uniform brightness across 16 strings. |
| Current Matching | ±3% (typ ±1%) - ensures consistent luminance across all 16 channels without external calibration. |
| PWM Dimming Resolution | 12-bit grayscale - provides 4096-step intensity control for smooth, flicker-free dimming. |
| Serial Interface Speed | 30MHz clock (SCKI) - enables fast configuration and fault readback for large LED arrays. |
| Min LED On-Time | 0.5µs - supports high-frequency PWM without pulse truncation, critical for color fidelity. |
| Package | 40-lead 6mm × 6mm QFN with exposed pad - optimized for thermal dissipation in high-current LED driving. |
Pinout & Package
LT3745EUJ#TRPBF is housed in a 40-lead plastic QFN (UJ package), 6mm × 6mm, with exposed thermal pad (Pin 41) soldered to PCB ground. Pin functions are validated per Linear Technology's official LT3745 datasheet Rev. F.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable & input UVLO input | Logic-level enable; also programs VIN UVLO threshold via resistor divider. |
| LED00–LED15 (2–9, 22–29) | LED cathode sink outputs | 16 independent constant-current sinks; each drives up to 36V LED string. |
| VIN (38), GATE (37), CAP (36), ISP/ISN (35/34) | Buck controller power & sensing | Drives external P-MOSFET; senses inductor current for peak-current-mode control. |
| ISET (40), TSET (39) | Current & temperature programming | Resistor-to-ground sets nominal LED current and overtemperature trip point. |
| SCKI/SDI/LDI (11/13/14), SCKO/SDO/LDO (20/18/17) | 6-wire serial interface | Enables cascadable, skew-balanced communication without external buffers. |
| FB (33), RT (31), SS (32) | Buck regulation & timing | Programs adaptive bus voltage, switching frequency, and soft-start ramp rate. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive LED bus voltage | Reduces power loss by dynamically adjusting buck output to match lowest forward-voltage string. |
| Per-channel 6-bit dot correction | Compensates for LED binning variations and PCB trace resistance differences across 16 channels. |
| Full diagnostic reporting | Real-time open/short LED and overtemperature flags returned via serial status frame. |
| 30MHz cascadable interface | Supports >100 chips in daisy chain with deterministic timing-no external clock trees required. |
| 0.5µs minimum PWM on-time | Preserves low-intensity accuracy in 12-bit dimming, avoiding grayscale compression at dark levels. |
Applications
| Large-Screen LCD Backlighting | Mono-/Full-Color LED Displays |
|---|---|
Use Scenario: Dynamic local dimming in 55″–110″ commercial LCD panels with zone-based brightness control. IC Role / Device Role / Timing Role: LT3745EUJ#TRPBF acts as the LED string driver and bus voltage controller; synchronizes PWM dimming across zones using PWMCK input. Use Value: Enables >10,000:1 contrast ratio via precise per-zone current control and adaptive bus voltage, reducing power by up to 35% vs fixed-bus designs. | Use Scenario: High-resolution outdoor LED video walls with pixel pitch ≤2.5mm requiring uniform luminance and thermal stability. IC Role / Device Role / Timing Role: LT3745EUJ#TRPBF serves as the channel driver IC; serial interface configures dot correction per module and reports open-circuit faults in real time. Use Value: ±1% typical current matching eliminates visible banding; 30MHz interface allows full panel refresh at 60Hz with <1ms latency. |
| LED Billboards | Architectural Signage |
Use Scenario: Large-format outdoor advertising displays operating continuously under variable ambient temperatures. IC Role / Device Role / Timing Role: LT3745EUJ#TRPBF manages thermal derating via TSET resistor and adjusts LED current based on junction temperature feedback. Use Value: Prevents thermal runaway by scaling current above 85°C; maintains consistent brightness across -40°C to +85°C ambient range. | Use Scenario: Indoor architectural lighting installations with RGBW LED modules requiring calibrated white-point stability. IC Role / Device Role / Timing Role: LT3745EUJ#TRPBF drives individual R/G/B/W strings with independent 6-bit dot correction and 12-bit PWM. Use Value: Achieves Δu'v' < 0.003 white-point consistency across modules using factory-programmed DC registers. |
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, higher-current (120mA) boost LED driver; no integrated serial interface or multi-channel control. | Used where high-voltage LED strings (>60V) require boost topology; lacks per-channel dimming or diagnostics. | Select when driving fewer, higher-Vf strings with simpler control; not suitable for multi-zone backlighting. |
| TLC5947RTQT | 24-channel 12-bit PWM LED driver (no buck controller); max 17V supply; I²C interface; no open/short detection. | Targets low-voltage, space-constrained RGB signage; requires external DC-DC for LED bus. | Choose for cost-sensitive, low-power indoor displays where adaptive bus voltage is unnecessary. |
Compared with LT3745EUJ#TRPBF, LT3761EUFD#TRPBF offers higher per-channel current but no multi-channel coordination, while TLC5947RTQT provides more channels at lower voltage and cost-but requires external power conversion and lacks fault reporting.
Availability
LT3745EUJ#TRPBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, mono-/full-color LED displays, LED billboards, and architectural signage requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT3745EUJ#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 technical and manufacturing continuity for the LT® product family, known for precision analog and power management ICs.
The LT3745EUJ#TRPBF belongs to Linear's high-performance LED driver product line, engineered specifically for demanding display applications requiring adaptive voltage control, tight current matching, and robust serial configurability.
FAQ
What is the maximum number of LT3745EUJ#TRPBF devices that can be cascaded in series?
The LT3745EUJ#TRPBF supports daisy-chaining 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 cascaded while maintaining signal integrity and skew balance-enabling control of 2048 LED channels from a single microcontroller interface.
Does LT3745EUJ#TRPBF support both DC and PWM dimming modes?
Yes, the LT3745EUJ#TRPBF supports two dimming methods: 6-bit dot correction (DC dimming) for coarse current adjustment per channel, and 12-bit grayscale PWM dimming synchronized to the external PWMCK input. Both are independently configurable via the serial interface and can be used simultaneously for fine-grained luminance control.
How is overtemperature protection implemented in LT3745EUJ#TRPBF?
Overtemperature protection in LT3745EUJ#TRPBF is programmed via a resistor from TSET (Pin 39) to GND. The internal TSET current (19.8µA typ) develops a voltage across this resistor; when it exceeds 510mV, the OT flag is asserted and reported in the serial status frame. No shutdown occurs-the device continues operation while signaling thermal stress.
Can LT3745EUJ#TRPBF drive LEDs with forward voltages exceeding 36V per string?
No. Each LEDxx output (Pins 2–9, 22–29) has a maximum rating of 40V, but the datasheet specifies safe operation up to 36V per string under normal conditions. Exceeding 36V risks violating the absolute maximum rating and may cause premature failure or reduced current matching accuracy.
What is the role of the CAP pin in LT3745EUJ#TRPBF, and what capacitor value is recommended?
The CAP pin (Pin 36) supplies the internal VIN-referenced 6.8V gate driver bias rail. A 0.47µF ceramic capacitor must be placed between CAP and VIN, as specified in the Typical Application circuit. This capacitor stabilizes the gate driver supply and ensures reliable MOSFET turn-on/turn-off timing under transient load conditions.
LT3745EUJ#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)
LT3745EUJ#TRPBF FAQ
1.How can I place an order for LT3745EUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3745EUJ#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 LT3745EUJ#TRPBF reliable?
The price and inventory of LT3745EUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3745EUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3745EUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3745EUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3745EUJ#TRPBF?
LT3745EUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3745EUJ#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 LT3745EUJ#TRPBF?
For technical support, including LT3745EUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3745EUJ#TRPBF requirements.
6.How does Aetrix verify that LT3745EUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3745EUJ#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 LT3745EUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3745EUJ#TRPBF?
All LT3745EUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3745EUJ#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 LT3745EUJ#TRPBF part is unused and in its original packaging.
Return procedure for LT3745EUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3745EUJ#TRPBF Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
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HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
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