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Analog Devices Inc. LT3743IUFD#PBF
- Part No.:
- LT3743IUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3743IUFD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:189
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Product details
Overview
LT3743IUFD#PBF 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 output, supports 6V–36V input, achieves ±6% current regulation accuracy, and enables sub-2µs transitions between two current levels-used in DLP projectors for precise RGB color mixing.
For engineers reviewing the LT3743IUFD#PBF datasheet, LT3743IUFD#PBF pinout, LT3743IUFD#PBF application, or LT3743IUFD#PBF equivalent, key selection criteria include its dual-analog-control architecture (CTRL_L/CTRL_H), programmable 200kHz–1MHz switching frequency via RT, integrated overvoltage/open-LED protection, and thermally enhanced 4mm × 5mm QFN package with exposed ground pad.
Technical Context
The LT3743IUFD#PBF implements average current mode control using dual independent reference inputs (CTRL_L and CTRL_H), each routed through dedicated compensation networks (VCL and VCH) to maintain stability across fast current-state transitions. Its switched-capacitor topology enables PWM dimming with up to 3000:1 ratio and <2µs recovery between regulated states.
It integrates high-side (HG) and low-side (LG) gate drivers with non-overlap timing (60–100ns), internal 5V VCC_INT regulator, and cycle-by-cycle overcurrent protection triggered by a 23mV offset above the CTRL_H-set sense voltage. The FB pin provides 1V feedback reference with open-LED detection at 1.3V.
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 - enables single-chip driving of high-power LEDs or laser diodes without parallel controllers. |
| Current Regulation Accuracy | ±6% - ensures consistent luminance and color point across temperature and line/load variations. |
| Switching Frequency Range | 200kHz to 1MHz - set by RT resistor; allows EMI optimization and inductor size trade-offs. |
| Recovery Time Between States | <2µs - critical for high-fidelity color mixing in RGB projection systems requiring rapid current slewing. |
| Shutdown Quiescent Current | <1µA - minimizes standby power in battery-backed or energy-sensitive lighting systems. |
| Package Thermal Resistance | θJA = 37°C/W - enabled by 28-lead 4mm × 5mm QFN with soldered exposed pad for high-power dissipation. |
Pinout & Package
LT3743IUFD#PBF is housed in a thermally enhanced 28-lead plastic QFN package (4mm × 5mm), featuring an exposed ground pad (Pin 29) that must be soldered to the PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1,5,9,20,21,29) | Power and signal reference ground | Multiple GND pins plus exposed pad reduce impedance and improve thermal conduction for high-current operation. |
| CTRL_H / CTRL_L | Analog current reference inputs | Set high/low regulated LED current levels (0–1.5V range); enable three-state dimming and color mixing. |
| CTRL_SEL | Digital current-level select | Switches error amplifier between VCH and VCL compensation networks to select CTRL_H or CTRL_L reference. |
| PWM | Global dimming enable | Active-low signal that halts switching and disconnects output capacitors - essential for zero-current blanking. |
| PWMGH / PWMGL | External capacitor switch drivers | Drive external FETs to connect/disconnect load capacitors - core to sub-2µs current-state transitions. |
| HG / LG | High-side and low-side gate drivers | Drive external N-channel MOSFETs with 2.3Ω/2.5Ω pull-up and 1.3Ω pull-down impedances for efficient switching. |
| SENSE+ / SENSE− | Current-sense differential inputs | Measure voltage drop across external sense resistor (RS) to close average inductor current loop. |
| FB | Voltage regulation and fault sensing | 1V reference; triggers open-LED shutdown when >1.3V; enables output voltage clamping via resistor divider. |
Key Features
| Feature | Design Value |
|---|---|
| Three-State Current Control | Enables independent analog programming of high/low LED currents (via CTRL_H/CTRL_L) and digital selection (via CTRL_SEL) - foundational for RGB color mixing without external DACs or microcontrollers. |
| Sub-2µs State Transition | Achieved via dual compensation networks (VCH/VCL) and switched-capacitor topology - eliminates color smearing in high-speed projection applications. |
| 3000:1 PWM Dimming Ratio | Supported by both PWM pin (global blanking) and CTRL_SEL pin (current-level switching) - meets cinema-grade contrast requirements. |
| Integrated Overvoltage & Open-LED Protection | FB pin monitors output; >1.3V triggers 13µs shutdown and simultaneous capacitor discharge - prevents LED damage during open-circuit faults. |
| Thermally Optimized QFN Package | 28-lead 4mm × 5mm body with exposed GND pad and θJA = 37°C/W - sustains 20A continuous operation with standard PCB copper area. |
Applications
| DLP Projectors | High-Power Architectural Lighting |
|---|---|
Use Scenario: Rapid sequential illumination of red, green, and blue LEDs in single-chip DLP engines to generate full-color images. IC Role / Device Role / Timing Role: Synchronous step-down controller providing precisely timed, high-current pulses (0A→2A→20A) with <2µs transition fidelity. Use Value: Eliminates need for multiple discrete drivers or FPGA-based timing control - reduces BOM count and system latency. | Use Scenario: Driving high-lumen LED arrays in commercial façade or stage lighting where smooth dimming and thermal stability are critical. IC Role / Device Role / Timing Role: High-efficiency (92%) current regulator delivering up to 20A with analog + PWM dimming support and overtemperature derating via CTRL_T. Use Value: Enables single-driver solutions for multi-string 48V LED arrays - simplifies thermal management and improves lumen maintenance. |
| Laser Diode Drivers | Automotive Headlight Modules |
Use Scenario: Precision current sourcing for pulsed or CW laser diodes in industrial marking and medical systems. IC Role / Device Role / Timing Role: Fast-recovery current controller with cycle-by-cycle overcurrent protection and <1µA shutdown leakage. Use Value: Prevents catastrophic diode failure during transient faults while supporting microsecond-scale pulse shaping. | Use Scenario: Adaptive front-lighting systems (AFS) requiring dynamic beam shaping via addressable LED segments. IC Role / Device Role / Timing Role: Robust LED driver with EN/UVLO (6V threshold), wide 6V–36V input range, and AEC-Q200-compatible thermal design. Use Value: Meets automotive cold-crank (6V) and load-dump (40V abs max) requirements without external protection circuitry. |
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 analog dimming input; no CTRL_SEL or dual-compensation; max 10A output. | Lacks three-state control and sub-2µs transition - suitable only for basic constant-current LED strings, not RGB mixing. | Select when cost sensitivity outweighs need for fast state switching or >10A output. |
| LM3409QMH/NOPB | Asynchronous buck controller; no integrated gate drivers; requires external high-side driver; max 5A typical. | No switched-capacitor topology or dual-reference architecture - cannot achieve 3000:1 dimming or rapid current slewing. | Choose for lower-cost, lower-current (<5A), non-mixing applications where layout simplicity is prioritized. |
Compared with LTC3783EFE#PBF and LM3409QMH/NOPB, the LT3743IUFD#PBF uniquely delivers 20A capability, three-state current control, and sub-2µs transitions - making it the only option among the three qualified for DLP projector color mixing and high-fidelity laser diode pulsing.
Availability
LT3743IUFD#PBF is available at Aetrix Electronics and suitable for DLP projectors, high-power architectural lighting, laser diode drivers, automotive headlight modules, and industrial display systems requiring stable component supply and long-term production continuity.
Supply support for LT3743IUFD#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.
The LT3743IUFD#PBF belongs to ADI's high-current LED driver product line, engineered specifically for applications demanding ultra-fast current-state transitions, precision analog dimming, and robust fault protection in compact form factors.
FAQ
What is the maximum regulated output current supported by the LT3743IUFD#PBF?
The LT3743IUFD#PBF supports up to 20A regulated LED current, achieved through external N-channel MOSFETs and a precision current-sense amplifier. This rating assumes proper thermal management using the exposed pad and appropriate PCB copper area, and is validated across the –40°C to 125°C operating junction temperature range specified for the 'I' grade device.
How does the LT3743IUFD#PBF achieve sub-2µs transitions between current levels?
The LT3743IUFD#PBF achieves <2µs recovery between regulated current states using a switched-capacitor topology with two independent output capacitors and dedicated compensation networks (VCH for high level, VCL for low level). When CTRL_SEL toggles, PWMGH/PWMGL drive external FETs to swap capacitors while precharging the inductor to 70% of the target current - all coordinated by internal timing delays and common-mode lockout.
What protection features are integrated into the LT3743IUFD#PBF?
The LT3743IUFD#PBF integrates cycle-by-cycle overcurrent protection (triggered by 23mV above CTRL_H-set sense voltage), open-LED detection (via FB pin >1.3V), internal UVLO on VIN and VCC_INT, thermal derating via CTRL_T input, and soft-start limiting via SS pin. All protections operate without external components and are active across the full –40°C to 125°C temperature range.
Can the LT3743IUFD#PBF be synchronized to an external clock?
Yes, the LT3743IUFD#PBF supports frequency synchronization via the SYNC pin, which accepts external clock signals from 240kHz to 1.2MHz. To avoid beat frequencies, the internal oscillator (set by RT) must be configured to run 20% slower than the SYNC frequency. When unused, SYNC must be grounded - floating operation is not permitted.
What is the role of the CTRL_T pin on the LT3743IUFD#PBF?
The CTRL_T pin on the LT3743IUFD#PBF provides thermal derating input: applying a voltage to this pin linearly reduces both CTRL_H- and CTRL_L-set current levels to prevent thermal runaway. It is typically connected to an NTC thermistor network; at 0V, full current is enabled, and at 3V, current is reduced to ~50% - enabling passive, analog-based thermal management without microcontroller intervention.
LT3743IUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT3743IUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3743IUFD#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 LT3743IUFD#PBF reliable?
The price and inventory of LT3743IUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3743IUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3743IUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3743IUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3743IUFD#PBF?
LT3743IUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3743IUFD#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 LT3743IUFD#PBF?
For technical support, including LT3743IUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3743IUFD#PBF requirements.
6.How does Aetrix verify that LT3743IUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3743IUFD#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 LT3743IUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3743IUFD#PBF?
All LT3743IUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3743IUFD#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 LT3743IUFD#PBF part is unused and in its original packaging.
Return procedure for LT3743IUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3743IUFD#PBF 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
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LYT1604D-TL
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HV9910CLG-G
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CL2N8-G
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
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