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Analog Devices Inc. LT3743IUFD#TRPBF
- Part No.:
- LT3743IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3743IUFD#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,316
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Product details
Overview
LT3743IUFD#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency synchronous step-down DC/DC controller optimized for high-current LED driving with three-state current control. It delivers up to 20A regulated LED current, supports 6V–36V input, achieves ±6% current regulation accuracy, and enables sub-2µs transitions between two current levels-used in DLP projectors for RGB color mixing.
For engineers reviewing the LT3743IUFD#TRPBF datasheet, LT3743IUFD#TRPBF pinout, LT3743IUFD#TRPBF application, or LT3743IUFD#TRPBF equivalent, key selection criteria include its dual-compensation average current mode architecture, 200kHz–1MHz programmable switching frequency, 3000:1 PWM dimming ratio, and thermal derating via CTRL_T pin-critical for high-power lighting and laser diode biasing.
Technical Context
The LT3743IUFD#TRPBF implements average current mode control with dual independent compensation networks (VCH/VCL) to maintain stable regulation during rapid transitions between two user-defined current levels (CTRL_L and CTRL_H). Its switched-capacitor topology enables <2µs recovery time by precharging the inductor to 70% of target current before capacitor switching.
It integrates cycle-by-cycle overcurrent protection triggered by a 23mV offset above the CTRL_H-set sense voltage, open-LED detection via FB pin (1.3V threshold), and internal 5V VCC_INT regulator with 50mA drive capability-enabling direct gate drive of external N-channel MOSFETs without external LDOs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 36V - supports wide industrial and automotive supply rails without external pre-regulation. |
| Max Output Current | 20A - delivered via external high-side and low-side N-MOSFETs; requires proper thermal design on 4mm × 5mm QFN exposed pad. |
| Current Regulation Accuracy | ±6% - guaranteed over –40°C to 125°C junction temperature, enabling precise LED brightness control in ambient-varying environments. |
| Switching Frequency Range | 200kHz to 1MHz - set by RT resistor; allows optimization of efficiency vs. size for inductors and output capacitors. |
| Recovery Time Between States | <2µs - achieved using dual output capacitors and synchronized PWMGH/PWMGL drivers, essential for high-fidelity color mixing in projection systems. |
| Dimming Ratio (PWM) | Up to 3000:1 - supported by dedicated PWM and CTRL_SEL pins, enabling deep black-level control in architectural and display lighting. |
| Shutdown Current | <1µA - enables ultra-low power standby in battery-backed or energy-sensitive applications. |
Pinout & Package
LT3743IUFD#TRPBF is housed in a thermally enhanced 28-lead (4mm × 5mm) plastic QFN package with exposed pad (Pin 29) soldered to PCB ground for optimal thermal dissipation (θJA = 37°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 5, 9, 20, 21, 29) | Power and signal reference ground | Multiple GND pins + exposed pad reduce impedance and improve current return path integrity for high di/dt switching. |
| CTRL_H / CTRL_L / CTRL_T | Analog current reference inputs | CTRL_H sets high-level LED current and overcurrent threshold; CTRL_L sets low-level current; CTRL_T provides thermal derating-each clamped to 1.5V max. |
| PWM / CTRL_SEL | Digital state selection inputs | PWM enables/disables all switching; CTRL_SEL selects between CTRL_H and CTRL_L references-enabling fast two-level current toggling. |
| PWMGH / PWMGL | External FET gate drivers | Drive gates of external NMOS switches connecting two separate output capacitors-key to sub-2µs current transitions. |
| HG / LG | High-side and low-side gate drivers | Integrated 5V gate drivers with 2.3Ω pull-up / 1.3Ω pull-down (HG) and 2.5Ω pull-up / 1.3Ω pull-down (LG) support fast, robust MOSFET switching. |
| SENSE+ / SENSE− | Current sense differential inputs | Measure voltage across external sense resistor (RS); internal error amplifier regulates inductor current based on 51mV typical sense threshold. |
| VCH / VCL | Compensation network connections | Separate compensation pins for high- and low-current regulation loops-prevents instability during rapid state changes. |
Key Features
| Feature | Design Value |
|---|---|
| Three-State Current Control | Enables precise RGB color mixing by independently regulating two LED current levels (via CTRL_L/CTRL_H) and selecting between them with CTRL_SEL-no external DAC or microcontroller required. |
| Dual Compensation Networks | VCH and VCL pins allow independent loop compensation for each current level, eliminating oscillation during µs-scale transitions-critical for projector color fidelity. |
| Sub-2µs State Recovery | Combines precharged inductor ramping, non-overlapping PWMGH/PWMGL timing (150ns delay), and dual output capacitors to achieve <2µs transition-enables >500kHz effective dimming bandwidth. |
| Integrated 5V VCC_INT Regulator | Delivers up to 50mA at 5V from VIN, powering internal circuitry and charging CBOOT capacitor-eliminates need for external bias supply in most designs. |
| Open-LED Protection | Monitors FB pin; triggers shutdown and discharges inductor when voltage exceeds 1.3V-prevents damage during LED string failure or open-circuit conditions. |
Applications
| DLP Projectors | High-Power Architectural Lighting |
|---|---|
Use Scenario: RGB LED arrays in digital light processing projectors require rapid, precise current switching to generate pure colors without color bleed. IC Role / Device Role / Timing Role: LT3743IUFD#TRPBF acts as a dual-level synchronous buck controller with µs-scale current state switching-serving as the core current source for red, green, and blue LED channels. Use Value: Sub-2µs recovery time and 3000:1 dimming ratio enable accurate grayscale reproduction and deep black levels in high-brightness projection systems. | Use Scenario: Outdoor floodlights and façade lighting demand high-efficiency, thermally robust LED drivers capable of sustained 10–20A operation under variable ambient temperatures. IC Role / Device Role / Timing Role: LT3743IUFD#TRPBF serves as the primary current-regulated step-down controller, interfacing with external high-current MOSFETs and thermal sensors (via CTRL_T). Use Value: ±6% current accuracy over –40°C to 125°C and integrated overvoltage/open-LED protection ensure consistent lumen output and system reliability in uncontrolled environments. |
| Laser Diode Biasing | Industrial Machine Vision Illumination |
Use Scenario: Pulsed laser diodes used in LiDAR and material processing require tightly controlled, fast-ramping current pulses with minimal overshoot. IC Role / Device Role / Timing Role: LT3743IUFD#TRPBF functions as a precision current source with analog-controlled amplitude (CTRL_H/CTRL_L) and digital triggering (PWM/CTRL_SEL)-replacing discrete op-amp + MOSFET solutions. Use Value: Cycle-by-cycle overcurrent limiting (23mV offset) and <1µA shutdown current prevent catastrophic failure during transient faults or standby modes. | Use Scenario: High-speed inspection systems use strobed LED arrays synchronized to camera exposure-requiring microsecond-level current turn-on/turn-off with repeatable amplitude. IC Role / Device Role / Timing Role: LT3743IUFD#TRPBF operates as a digitally triggered, analog-programmed current driver-accepting TTL-level PWM signals while maintaining constant current during active illumination windows. Use Value: 200kHz–1MHz frequency programmability allows matching of switching to camera frame rates; soft-start (SS pin) prevents inrush-induced mechanical vibration in precision optics mounts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-current LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Fixed-frequency current-mode controller with single current level; no dual-compensation or sub-2µs recovery; supports up to 15A. | Lacks three-state control and fast transition capability-suitable only for single-level dimming or non-color-mixing applications. | Select when cost sensitivity outweighs need for RGB color mixing or ultra-fast dimming. |
| LM3409QMH/NOPB | Constant-current buck controller with analog/PWM dimming; max 5A output; no dual-state architecture or integrated VCC_INT regulator. | Designed for lower-power LED strings; lacks thermal derating (CTRL_T) and open-LED protection with timeout. | Choose for automotive interior lighting or indicator LEDs where 20A capability and projector-grade timing are unnecessary. |
Compared with LTC3783EFE#PBF and LM3409QMH/NOPB, the LT3743IUFD#TRPBF uniquely delivers dual-level current regulation with sub-2µs transitions, integrated 5V bias, and thermal derating-making it the only option qualified for DLP projector color engines and high-end architectural luminaires requiring dynamic current shaping.
Availability
LT3743IUFD#TRPBF is available at Aetrix Electronics and suitable for DLP projectors, high-power architectural lighting, laser diode biasing, and industrial machine vision illumination requiring stable component supply across extended temperature ranges.
Supply support for LT3743IUFD#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 LT® series.
The LT3743IUFD#TRPBF belongs to Linear's high-current LED driver product line, engineered specifically for applications demanding precise, fast-switching current regulation-especially RGB color mixing in projection and high-lumen architectural systems.
FAQ
What is the maximum LED current supported by the LT3743IUFD#TRPBF?
The LT3743IUFD#TRPBF supports up to 20A regulated LED current when paired with appropriately rated external MOSFETs and thermal management. This is achieved through its average current mode control architecture and dual-output-capacitor topology. The actual achievable current depends on layout, heatsinking, input voltage, and sense resistor value (e.g., 2mΩ RS yields ~20A). The LT3743IUFD#TRPBF itself does not limit current-overcurrent protection is set via CTRL_H and sense resistor scaling.
How does the LT3743IUFD#TRPBF achieve sub-2µs current transitions between levels?
The LT3743IUFD#TRPBF achieves <2µs recovery using three coordinated mechanisms: (1) precharging the inductor to 70% of the target current before capacitor switching, (2) non-overlapping 150ns delay between PWMGL and PWMGH activation, and (3) dual independent compensation networks (VCH/VCL) that remain stable during state change. These features are intrinsic to the LT3743IUFD#TRPBF silicon design and require no external configuration.
Can the LT3743IUFD#TRPBF operate without an external microcontroller?
Yes-the LT3743IUFD#TRPBF is fully autonomous. It accepts analog voltage inputs (CTRL_H, CTRL_L, CTRL_T) and digital logic signals (PWM, CTRL_SEL) directly. No firmware, I²C interface, or processor is needed to configure dimming levels, switching frequency (set by RT resistor), or protection thresholds. All critical functions-including open-LED detection, overcurrent limiting, and soft-start-are implemented in hardware within the LT3743IUFD#TRPBF.
What is the role of the CTRL_T pin on the LT3743IUFD#TRPBF?
The CTRL_T pin on the LT3743IUFD#TRPBF provides analog thermal derating: applying a voltage (0–1.5V) reduces both CTRL_H- and CTRL_L-set current levels proportionally to prevent overheating. It does not shut down the device but scales regulated current downward as temperature rises-enabling graceful degradation instead of abrupt fault shutdown. This function is unique to the LT3743IUFD#TRPBF and is not present in most competing LED controllers.
Does the LT3743IUFD#TRPBF require external gate drivers for the MOSFETs?
No-the LT3743IUFD#TRPBF integrates high-side (HG) and low-side (LG) gate drivers capable of directly driving N-channel MOSFETs, plus dedicated PWMGH/PWMGL outputs for external capacitor-switching FETs. Its HG driver has 2.3Ω pull-up / 1.3Ω pull-down impedance; LG has 2.5Ω pull-up / 1.3Ω pull-down. These specifications are published in the LT3743IUFD#TRPBF electrical characteristics table and eliminate need for external drivers in most 20A-class designs.
LT3743IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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:
- 1
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 36V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 200kHz ~ 1MHz
- Dimming:
- PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT3743IUFD#TRPBF FAQ
1.How can I place an order for LT3743IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3743IUFD#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 LT3743IUFD#TRPBF reliable?
The price and inventory of LT3743IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3743IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3743IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3743IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3743IUFD#TRPBF?
LT3743IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3743IUFD#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 LT3743IUFD#TRPBF?
For technical support, including LT3743IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3743IUFD#TRPBF requirements.
6.How does Aetrix verify that LT3743IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3743IUFD#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 LT3743IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3743IUFD#TRPBF?
All LT3743IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3743IUFD#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 LT3743IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT3743IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3743IUFD#TRPBF Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
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BCR420UE6433HTMA1
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
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LYT1604D-TL
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HV9910CLG-G
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CL2N8-G
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BCR420UW6-7
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BCR421UW6-7
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
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