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Analog Devices Inc. LT3745IUJ-1#PBF
- Part No.:
- LT3745IUJ-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT3745IUJ-1#PBF.pdf
- Description:
- IC LED DRVR CTRLR PWM 75MA 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,017
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Product details
Overview
LT3745IUJ-1#PBF 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 ±4% LED current matching at 50mA per channel, supports 12-bit grayscale PWM dimming and 6-bit dot correction via LVDS serial interface, and is designed for large-screen LCD dynamic backlighting requiring precise per-channel current control and high-speed data cascading.
For engineers reviewing the LT3745IUJ-1#PBF datasheet, LT3745IUJ-1#PBF pinout, LT3745IUJ-1#PBF application, or LT3745IUJ-1#PBF equivalent, key selection considerations include its 40-lead 6mm × 6mm QFN package, 30MHz cascadable LVDS interface, ±4% inter-channel current matching, 0.5µs minimum LED on-time, and integrated open/short LED + overtemperature diagnostics.
Technical Context
The LT3745IUJ-1#PBF integrates a current-mode nonsynchronous buck controller with sixteen linear current sinks. The buck stage regulates an adaptive LED bus voltage (up to 36V) based on feedback from the highest-voltage LED string, while each sink channel independently regulates 25–75mA using ISET-programmed reference and 6-bit DAC-adjusted current.
Its 30MHz LVDS serial interface uses differential SCKI+/SCKI−, SDI+/SDI−, SCKO+/SCKO−, and SDO+/SDO− pairs for noise-immune, multi-chip cascading; LDI provides TTL/CMOS latch timing. Diagnostics-including per-channel open/short LED detection and TSET-programmable overtemperature flag-are reported back through the same serial interface.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Channels | 16 independent constant-current sinks, each configurable from 25mA to 75mA |
| Current Matching | ±4% typical mismatch between channels at 50mA - enables uniform brightness across large displays |
| PWM Dimming | 12-bit grayscale resolution (4096 levels) with 0.5µs minimum on-time - supports high-frequency, flicker-free dimming |
| Serial Interface | 30MHz fully-buffered LVDS with cascadable SCKO/SDO - allows daisy-chaining >100 chips without signal degradation |
| Buck Input Range | 6V to 55V VIN - accommodates wide-input industrial and automotive LED power supplies |
| Diagnostic Coverage | Per-channel open/short LED detection + programmable overtemperature shutdown - reduces system-level fault debugging time |
| Package | 40-lead 6mm × 6mm QFN with exposed thermal pad - supports >1.5W continuous power dissipation in compact layouts |
Pinout & Package
LT3745IUJ-1#PBF is housed in a 40-lead plastic QFN package (6mm × 6mm), with Pin 41 (exposed pad) electrically and thermally connected to GND and required to be soldered to a continuous PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LED00–LED15 (Pins 2–9, 22–29) | Constant-current sink outputs | Drive LED string cathodes; each supports up to 36V reverse voltage and 75mA sink current |
| SCKI+, SCKI− (Pins 10, 11) | LVDS serial clock input | Accept 30MHz differential clock for synchronous data shifting into internal 194-bit shift register |
| SDI+, SDI− (Pins 12, 13) | LVDS serial data input | Receive 194-bit frames (GS or DC) with MSB-first order; internally latched by LDI edge |
| LDI (Pin 14) | TTL/CMOS latch strobe | Asynchronous edge-triggered load signal that transfers shift register contents to GS/DC registers |
| VCC (Pin 15) | Digital supply rail | Powers LVDS receivers/transceivers and logic circuitry; requires local 1µF bypass to GND |
| PWMCK+, PWMCK− (Pins 16, 17) | LVDS PWM clock input | Drives 12-bit counter per channel to generate precise grayscale PWM duty cycles |
| SDO+, SDO− (Pins 18, 19) | LVDS serial data output | Transmit 194-bit status frame (OT flag + 16× LED fault bits + 16× DC settings) on SCKO edge |
| SCKO+, SCKO− (Pins 20, 21) | LVDS serial clock output | Forward clock to next device in cascade; matched skew with SDO ensures reliable inter-chip timing |
| ISET (Pin 40) | Nominal current programming | Resistor-to-GND sets base LED current (e.g., 60.4kΩ → 50mA); trimmed VISET = 1.205V ±0.024V |
| TSET (Pin 39) | Overtemperature threshold | Resistor-to-GND programs junction trip point (e.g., 100kΩ → ~115°C); outputs OT flag to status frame |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive LED bus voltage | Automatically adjusts buck output to match highest-string forward voltage - improves system efficiency by minimizing excess headroom |
| 12-bit grayscale + 6-bit dot correction | Enables per-channel brightness calibration and fine-grained intensity control - essential for color accuracy in RGB LED displays |
| Full diagnostic reporting | Real-time open/short LED and overtemperature status returned via serial interface - eliminates need for external sense circuitry |
| Cascadable 30MHz LVDS interface | Supports >100-device chains with deterministic timing and minimal interconnect EMI - ideal for ultra-large video walls |
| Thermally robust QFN package | θJC = 2.5°C/W with exposed pad soldered to PCB - sustains full 50mA/channel operation at TJ ≤ 125°C ambient |
Applications
| Large-Screen LCD Backlighting | Mono-Color LED Video Walls |
|---|---|
Use Scenario: Dynamic local dimming of 65-inch+ LCD panels using 16 parallel LED strings per zone. IC Role / Device Role / Timing Role: LT3745IUJ-1#PBF acts as zone-level LED driver and bus voltage controller, synchronizing PWM dimming across all 16 channels via shared PWMCK. Use Value: Achieves >10,000:1 contrast ratio with 0.5µs minimum on-time enabling high-frequency dimming without visible flicker. |
Use Scenario: Outdoor monochrome signage with 128×64 pixel density driven by cascaded LT3745IUJ-1#PBF arrays. IC Role / Device Role / Timing Role: LT3745IUJ-1#PBF serves as column driver with LVDS daisy-chain enabling single-controller control of 256+ channels. Use Value: 30MHz LVDS interface ensures <5ns inter-device skew - critical for synchronized row/column scanning. |
| Full-Color RGB LED Displays | Industrial LED Billboards |
Use Scenario: High-brightness RGB modules where per-pixel white-point calibration is required. IC Role / Device Role / Timing Role: LT3745IUJ-1#PBF provides independent 6-bit dot correction per R/G/B channel to compensate for LED binning variance. Use Value: ±1% typical current matching between devices (ΔILEDD) ensures consistent chromaticity across display tiles. |
Use Scenario: Highway-facing digital billboards operating continuously at 55°C ambient temperature. IC Role / Device Role / Timing Role: LT3745IUJ-1#PBF monitors die temperature via TSET and disables affected zones before thermal runaway occurs. Use Value: Integrated overtemperature protection with programmable threshold avoids external thermal sensors and reduces BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3745EUJ-1#PBF | Same silicon, extended temperature grade (–40°C to 125°C vs. –40°C to 125°C - identical spec; E-grade denotes enhanced screening) | No functional difference; E-grade used in aerospace/military where lot traceability and burn-in are mandated | Select LT3745EUJ-1#PBF only if qualification to MIL-STD-883 or AEC-Q200 stress testing is contractually required. |
| LT3745UJ-1 | Lead-based finish (non-RoHS), otherwise identical electrical specs and pinout | Restricted to legacy industrial equipment where lead-free compliance is not enforced | Choose LT3745UJ-1 only when leaded solder assembly is unavoidable and RoHS exemption applies. |
Compared with LT3745IUJ-1#PBF, the LT3745EUJ-1#PBF offers no performance advantage but adds screening rigor for mission-critical systems, while the LT3745UJ-1 sacrifices environmental compliance for compatibility with SnPb reflow - neither provides pin-compatible upgrade paths nor functional differentiation in standard commercial designs.
Availability
LT3745IUJ-1#PBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, mono-color LED video walls, full-color RGB displays, and industrial LED billboards requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LT3745IUJ-1#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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LT3745 family.
The LT3745IUJ-1#PBF belongs to Linear's high-performance LED driver product line, engineered specifically for demanding display applications requiring precision current matching, high-speed serial control, and integrated diagnostics.
FAQ
What is the maximum LED string voltage supported per channel of the LT3745IUJ-1#PBF?
The LT3745IUJ-1#PBF supports up to 36V LED string voltage per channel, as confirmed by the Absolute Maximum Rating for LED00–LED15 pins (40V) and Electrical Characteristics specifying "LEDxx Operating Voltage" at 36V under full operating conditions. This allows driving 10–12 white LEDs in series at typical forward voltages.
Does the LT3745IUJ-1#PBF require external current-sense resistors for LED regulation?
No, the LT3745IUJ-1#PBF does not use external sense resistors for LED current regulation. Each channel employs an internal current mirror referenced to the ISET pin voltage (1.205V ±0.024V); current setting is accomplished solely by the resistor from ISET to GND, eliminating board space and tolerance errors associated with discrete sense resistors.
Can the LT3745IUJ-1#PBF operate without the LVDS interface enabled?
Yes, the LT3745IUJ-1#PBF can operate with static LED current output by holding LDI low and preloading GS/DC registers during initialization. However, full functionality-including grayscale dimming, dot correction updates, and fault readback-requires active LVDS communication; disabling the interface forfeits dynamic control and diagnostics.
What is the purpose of the TSET pin on the LT3745IUJ-1#PBF?
The TSET pin on the LT3745IUJ-1#PBF programs the overtemperature shutdown threshold via an external resistor to GND. Its output current (19.8µA typical) flows through the resistor to generate a voltage; when this voltage exceeds 510mV, the internal OT flag is asserted and reported in the serial status frame, allowing system-level thermal management.
How does the LT3745IUJ-1#PBF achieve adaptive LED bus voltage control?
The LT3745IUJ-1#PBF achieves adaptive LED bus voltage by monitoring the highest forward voltage among all 16 LED strings via the FB pin. The integrated buck controller dynamically adjusts its output to maintain just enough headroom (typically 0.5–1V) above the highest string voltage, minimizing power loss in the linear current sinks while ensuring all strings remain properly biased.
LT3745IUJ-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tube
- 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-1#PBF FAQ
1.How can I place an order for LT3745IUJ-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3745IUJ-1#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 LT3745IUJ-1#PBF reliable?
The price and inventory of LT3745IUJ-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3745IUJ-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3745IUJ-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3745IUJ-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3745IUJ-1#PBF?
LT3745IUJ-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3745IUJ-1#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 LT3745IUJ-1#PBF?
For technical support, including LT3745IUJ-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3745IUJ-1#PBF requirements.
6.How does Aetrix verify that LT3745IUJ-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3745IUJ-1#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 LT3745IUJ-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3745IUJ-1#PBF?
All LT3745IUJ-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3745IUJ-1#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 LT3745IUJ-1#PBF part is unused and in its original packaging.
Return procedure for LT3745IUJ-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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