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Analog Devices Inc. LT3797ELXE#PBF
- Part No.:
- LT3797ELXE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
LT3797ELXE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 48LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:1,203
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Product details
Overview
LT3797ELXE#PBF from Analog Devices is a triple-output DC/DC LED controller IC designed for independent high-side current sensing and flexible topology operation (boost, buck, buck-boost, SEPIC, flyback) across three LED channels. It supports 2.5V–40V input, 100V rail-to-rail LED sense range, 3000:1 PWM dimming, and integrated 7.5V INTVCC supply - used in automotive headlamps, RGB signage, and large-format displays.
For engineers reviewing the LT3797ELXE#PBF datasheet, LT3797ELXE#PBF pinout, LT3797ELXE#PBF application, or LT3797ELXE#PBF equivalent, key selection considerations include per-channel open-LED/overvoltage fault flags, high-side ISP/ISN sensing capability, FBH-referenced voltage loop, TG-driven PMOS disconnect, and 48-pin eLQFP thermal performance at –40°C to 125°C.
Technical Context
The LT3797ELXE#PBF implements fixed-frequency current-mode control with independent error amplifiers (VC1–VC3), high-side current sense inputs (ISP1–ISP3/ISN1–ISN3), and FBH pins referenced to ISP for dual-loop regulation. Each channel features dedicated soft-start (SS1–SS3), analog dimming (CTRL1–CTRL3), and fault reporting (FLT1–FLT3).
Its integrated INTVCC converter (7.5V ±0.35V) powers NMOS gate drivers (GATE1–GATE3) and logic, while TG1–TG3 provide level-shifted PWM outputs for external PMOS LED disconnect. Switching frequency is adjustable from 100kHz to 1MHz via RT resistor or synchronizable to external clock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 40V continuous; survives 60V transients - enables direct battery-input designs without pre-regulation. |
| LED Current Sense Range | Rail-to-rail 0V to 100V common-mode on ISN pins - supports high-side sensing in boost/buck-boost topologies. |
| Switching Frequency | 100kHz to 1MHz (RT-programmable); synchronizable - allows EMI optimization and inductor size reduction. |
| PWM Dimming Ratio | 3000:1 - delivers precise brightness control in high-dynamic-range lighting applications. |
| INTVCC Output | 7.5V ±0.35V regulated supply - powers gate drivers and internal circuitry without external LDO. |
| Fault Protection | Per-channel open-LED, overcurrent, overvoltage (FBH), thermal shutdown, VIN OVLO/UVLO - enables robust system-level safety. |
| Operating Temperature | –40°C to 125°C junction - qualified for automotive and industrial ambient environments. |
Pinout & Package
LT3797ELXE#PBF uses a 48-lead (7mm × 7mm) plastic eLQFP package with exposed pad (Pin 49 = GND). Thermal resistance θJA = 19°C/W. Exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP1–ISP3 | High-side current sense positive input | Serves as reference rail for TG drivers and FBH feedback; enables true high-side sensing up to 100V. |
| ISN1–ISN3 | High-side current sense negative input | Accepts 0V–100V common-mode voltage; Kelvin connection required for accurate current regulation. |
| FBH1–FBH3 | Voltage loop feedback input | Measures |ISP–FBH| to regulate output voltage during open-LED events; threshold = 1.25V ±25mV. |
| TG1–TG3 | PMOS gate driver output | Level-shifted inverted PWM output; drives external P-channel MOSFETs between ISP and (ISP – 6.5V). |
| GATE1–GATE3 | NMOS gate driver output | Drives external N-channel switches between INTVCC and GND; min. on/off time = 220ns/200ns. |
| CTRL1–CTRL3 | Analog dimming control input | Adjusts LED current threshold from 0mV to 250mV linearly (0.2V–1.2V range); idle below 150mV. |
| FLT1–FLT3 | Open-collector fault flag output | Asserts low for channel-specific faults: open-LED, overcurrent, overvoltage, thermal, VIN OVLO/UVLO. |
| SS1–SS3 | Soft-start timing capacitor node | Controls ramp-up of VC voltage; external capacitor sets soft-start duration per channel. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent LED controllers | Each channel operates autonomously with dedicated CTRL, SS, FLT, VC, and sensing - eliminates cross-talk in multi-string RGB or white+amber systems. |
| High-side current sensing architecture | ISP/ISN inputs referenced to LED string anode - enables boost, buck, and buck-boost topologies without ground-referenced shunt limitations. |
| Dual-loop regulation (current + voltage) | FBH pin enables constant-voltage mode during open-LED fault; prevents overvoltage damage while maintaining current regulation under normal operation. |
| Integrated 7.5V INTVCC power supply | Eliminates need for external bias supply; powers gate drivers and logic from VIN - simplifies BOM and improves efficiency in wide-input designs. |
| PMOS LED disconnect with TG drivers | TG outputs drive external P-MOSFETs to fully isolate LED strings during fault or dimming - ensures zero leakage current and enhanced safety. |
| Programmable fault thresholds & hysteresis | OVLO (1.25V), EN/UVLO (1.22V), and FBH thresholds include user-adjustable hysteresis - enables stable startup and noise-immune protection. |
Applications
| Automotive Adaptive Headlamps | RGB Video Billboards |
|---|---|
Use Scenario: Dynamic beam shaping using separate red, green, and blue LED strings with independent brightness and timing control. IC Role / Device Role / Timing Role: LT3797ELXE#PBF acts as triple-channel LED current controller with synchronized PWM dimming and per-string open-circuit detection. Use Value: Enables pixel-level color accuracy and flicker-free video playback via 3000:1 PWM dimming and fast fault response (<1µs). |
Use Scenario: Outdoor large-format display requiring high-brightness, thermally robust LED driving across thousands of modules. IC Role / Device Role / Timing Role: LT3797ELXE#PBF provides three independent boost/buck-boost channels per module, each driving parallel LED strings with high-side sensing. Use Value: Rail-to-rail 0V–100V ISN sensing allows direct connection to high-voltage LED strings; exposed-pad LQFP ensures thermal reliability at 125°C ambient. |
| Industrial Machine Vision Lighting | Architectural Color-Tunable Fixtures |
Use Scenario: Stroboscopic illumination synchronized to camera exposure with precise intensity control per spectral band. IC Role / Device Role / Timing Role: LT3797ELXE#PBF serves as timing-critical LED driver with SYNC input for external clock alignment and programmable soft-start per channel. Use Value: Synchronization tolerance <0.2µs and independent SS1–SS3 allow phase-aligned strobe pulses across R/G/B channels without inter-channel delay skew. |
Use Scenario: Tunable-white and full-color architectural lighting with CCT and chromaticity adjustment via analog + PWM dimming. IC Role / Device Role / Timing Role: LT3797ELXE#PBF delivers simultaneous analog (CTRL) and PWM dimming on all three channels for smooth color mixing. Use Value: Linear CTRL dimming (0.2V–1.2V) combined with 3000:1 PWM enables seamless 0–100% intensity control without color shift or stepping artifacts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3797EUKG#PBF | Same die, 52-lead QFN (7mm × 8mm); θJA = 28°C/W vs. 19°C/W for LQFP | Better suited for space-constrained layouts where thermal mass is less critical than footprint | Select when board area is tighter than thermal budget; verify PCB copper pour for QFN thermal relief. |
| LT3965EFE#PBF | Dual-channel, 4-switch synchronous buck controller; no integrated INTVCC; max 60V input | Lacks third channel and high-side sensing; requires external bias supply and separate PMOS drivers | Choose only if dual-channel suffices and system already includes bias rails; not drop-in compatible. |
Compared with LT3797EUKG#PBF, the LT3797ELXE#PBF offers superior thermal performance in high-power density designs; versus LT3965EFE#PBF, it provides native triple-channel integration, high-side sensing, and self-contained bias - reducing component count and layout complexity.
Availability
LT3797ELXE#PBF is available at Aetrix Electronics and suitable for automotive lighting, outdoor signage, and industrial machine vision applications requiring stable component supply, extended temperature operation, and long-term production continuity.
Supply support for LT3797ELXE#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. is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, power management, and signal conditioning.
The LT3797 product line was engineered specifically for high-reliability, multi-string LED lighting systems demanding independent channel control, wide input range, and robust fault handling - targeting automotive, industrial, and architectural applications.
FAQ
What is the maximum LED string voltage supported by the LT3797ELXE#PBF?
The LT3797ELXE#PBF supports rail-to-rail LED current sense common-mode voltage from 0V to 100V on its ISN pins. This enables direct high-side sensing in boost configurations where LED string cathodes connect to ground and anodes reach up to 100V - verified across the full –40°C to 125°C operating range.
Does the LT3797ELXE#PBF require external components for its 7.5V INTVCC supply?
No. The LT3797ELXE#PBF integrates a dedicated DC/DC converter that generates a regulated 7.5V ±0.35V supply (INTVCC) from VIN. Only two external components are required: a 0.1µF BOOST capacitor between BOOST and SW1, and a 10µF ceramic bypass capacitor on each INTVCC pin - no external regulator or inductor needed.
How does the LT3797ELXE#PBF handle open-LED faults across its three channels?
The LT3797ELXE#PBF detects open-LED conditions per channel using the FBH pin: when |ISP–FBH| exceeds the rising threshold (FBH(REG) – 0.05V), the corresponding VC amplifier regulates to maintain 1.25V, and the TG driver pulls high to disconnect the external PMOS. FLT1–FLT3 assert open-collector low independently - enabling selective channel shutdown without affecting others.
Can the LT3797ELXE#PBF operate in buck topology for all three channels simultaneously?
Yes. The LT3797ELXE#PBF supports buck, boost, buck-boost, SEPIC, and flyback topologies per channel. For buck operation, connect the LED string between VIN and the switch node (SWx), use ISPx as high-side sense point, and configure FBHx for optional voltage regulation - confirmed in Analog Devices' LT3797 demo circuits DC2222A and DC2223A.
What is the purpose of the CTRL1–CTRL3 pins on the LT3797ELXE#PBF?
The CTRL1–CTRL3 pins on the LT3797ELXE#PBF set the LED current sense threshold voltage (VISP–ISN) linearly from 0mV to 250mV over 0.2V–1.2V input range. At VCTRL = 2V, threshold clamps at 250mV; below 150mV, the channel enters idle mode - enabling precise analog dimming and thermal derating without PWM modulation.
LT3797ELXE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 48-LQFP Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Flyback, SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 3
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 48-LQFP-EP (7x7)
LT3797ELXE#PBF FAQ
1.How can I place an order for LT3797ELXE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3797ELXE#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 LT3797ELXE#PBF reliable?
The price and inventory of LT3797ELXE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3797ELXE#PBF is usually 5 days.
3.What payment methods are accepted for LT3797ELXE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3797ELXE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3797ELXE#PBF?
LT3797ELXE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3797ELXE#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 LT3797ELXE#PBF?
For technical support, including LT3797ELXE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3797ELXE#PBF requirements.
6.How does Aetrix verify that LT3797ELXE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3797ELXE#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 LT3797ELXE#PBF meets industry standards.
7.What is the process for return or replacement of LT3797ELXE#PBF?
All LT3797ELXE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3797ELXE#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 LT3797ELXE#PBF part is unused and in its original packaging.
Return procedure for LT3797ELXE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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