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Analog Devices Inc. LT3797ILXE#PBF
- Part No.:
- LT3797ILXE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
LT3797ILXE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 48LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:1,853
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Product details
Overview
LT3797ILXE#PBF from Analog Devices is a triple-output DC/DC LED driver controller supporting boost, buck, buck-boost, SEPIC, and flyback topologies per channel. It operates from 2.5V to 40V input (60V transient tolerant), delivers rail-to-rail LED current sense (0V–100V), enables 3000:1 PWM dimming, and integrates a 7.5V INTVCC supply for N-channel gate drivers - used in automotive RGB lighting and large-format displays.
For engineers reviewing the LT3797ILXE#PBF datasheet, LT3797ILXE#PBF pinout, LT3797ILXE#PBF application, or LT3797ILXE#PBF equivalent, key selection criteria include high-side current sensing capability, independent fault flag reporting per channel, programmable soft-start, synchronized switching up to 1MHz, and compatibility with external P-channel LED disconnect MOSFETs via TG drivers.
Technical Context
The LT3797ILXE#PBF implements fixed-frequency current-mode control across three fully independent channels, each with dedicated VC error amplifier, SS soft-start, FLT fault output, and dual-loop regulation (current + voltage). Its architecture supports topology flexibility by referencing FBH to ISP and enabling high-side current sensing through ISP/ISN differential inputs.
Each channel features independent analog dimming via CTRL pins (0.2V–1.2V range), PWM-controlled idle mode, open-LED and overvoltage protection triggered at |ISP−FBH| thresholds (1.25V regulation, ±50mV hysteresis), and integrated 7.5V INTVCC generation capable of driving external NMOS gates without auxiliary supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 40V continuous; withstands 60V transients - enables direct battery-input operation in 12V/24V automotive systems without pre-regulation. |
| LED Current Sense Range | Rail-to-rail 0V to 100V common-mode - allows high-side sensing in boost configurations where LED cathode connects to ground. |
| Switching Frequency | 100kHz to 1MHz, adjustable via RT resistor or synchronizable to external clock - supports EMI optimization and compact magnetics design. |
| PWM Dimming Ratio | 3000:1 - achieves deep dimming in architectural and signage lighting without visible flicker or color shift. |
| INTVCC Output | 7.5V ±3%, 150mA typical - powers all internal logic and external N-channel MOSFET gate drivers without secondary supply. |
| Fault Reporting | Three independent open-collector FLT pins - signal per-channel faults including open-LED, overcurrent, overvoltage, thermal shutdown, and VIN OVLO. |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive and industrial ambient environments. |
Pinout & Package
LT3797ILXE#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 |
|---|---|---|
| ISP1–3 / ISN1–3 | High-side LED current sense differential inputs | Enable Kelvin-connected sense resistors on LED string anode side - critical for accurate current regulation in boost and SEPIC topologies. |
| FBH1–3 | Voltage feedback reference input (referred to ISP) | Sets 1.25V regulated |ISP−FBH| threshold for open-LED detection and constant-voltage protection - disables if ISP < 4.5V. |
| TG1–3 | P-channel MOSFET gate driver outputs | Drive external PMOS between ISP and (ISP − 6.5V) to disconnect LEDs during fault - provides short-circuit protected boost capability. |
| GATE1–3 | N-channel MOSFET gate drivers | Output swing from GND to INTVCC (7.5V) with 25ns rise/fall times - directly drives external NMOS switches without level-shifting. |
| FLT1–3 | Open-collector fault status outputs | Assert low for channel-specific faults (VIN OVLO, thermal shutdown, INTVCC UVLO, open-LED, overvoltage, overcurrent) - enables discrete fault monitoring. |
| CTRL1–3 | Analog dimming threshold adjustment inputs | Set LED current sense threshold from 17mV to 250mV linearly (0.2V–1.2V range) - enables temperature-compensated dimming when referenced to VREF. |
| SS1–3 | Per-channel soft-start timing inputs | Capacitor-programmed ramp controls startup dI/dt - prevents inrush current in multi-string LED arrays. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent DC/DC controllers | Each channel supports unique topology (boost/buck/buck-boost/SEPIC/flyback) and independent dimming/fault management - eliminates need for multiple ICs in RGB or segmented lighting. |
| High-side current sensing | ISP/ISN inputs tolerate 0V–100V common-mode voltage - enables boost LED drivers with grounded cathodes and simplifies layout vs. low-side sensing. |
| Integrated 7.5V INTVCC supply | Regulated output powers internal circuitry and external NMOS gate drivers - removes requirement for auxiliary bias supply and reduces BOM count. |
| 3000:1 PWM dimming | Supports full-range brightness control down to 0.033% duty cycle - meets stringent requirements for cinema-grade and medical display lighting. |
| Per-channel fault flags | Three dedicated FLT pins report open-LED, overvoltage, overcurrent, thermal, and supply faults - enables targeted diagnostics and graceful degradation in multi-string systems. |
| Programmable soft-start | SS1–3 pins accept external capacitors to set individual channel startup time - prevents current surges when powering multiple LED strings simultaneously. |
Applications
| Automotive Headlamp Control | RGB Stage Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with separate white LED high/low beams and amber DRLs, requiring independent current regulation and fault isolation. IC Role / Device Role / Timing Role: LT3797ILXE#PBF acts as triple-channel LED current controller with per-channel PWM dimming, open-LED detection, and thermal fault reporting - managing beam pattern switching and safety redundancy. Use Value: Enables single-chip control of three optically distinct LED arrays while meeting ISO 16750-2 automotive transient immunity (60V surge) and AEC-Q100 Grade 1 requirements. |
Use Scenario: High-brightness theatrical fixture with independently dimmable red, green, and blue LED strings for precise color mixing and dynamic effects. IC Role / Device Role / Timing Role: LT3797ILXE#PBF provides synchronized 3000:1 PWM dimming across all three channels with matched rise/fall times - ensuring flicker-free color transitions and stable white-point tracking. Use Value: Eliminates inter-channel timing skew and current drift, preserving color fidelity across intensity ranges without external microcontroller coordination. |
| Outdoor Digital Billboards | Industrial Machine Vision Lighting |
Use Scenario: Large-format LED display module with hundreds of parallel LED strings grouped into R/G/B zones, exposed to wide ambient temperature swings and line voltage variations. IC Role / Device Role / Timing Role: LT3797ILXE#PBF serves as topology-flexible LED driver controller supporting boost configuration per color zone - regulating current despite 2.5V–40V input variation from solar/battery sources. Use Value: Maintains consistent luminance across operating temperature (–40°C to +125°C) and input voltage range, reducing thermal derating and extending display lifetime. |
Use Scenario: High-speed inspection system using pulsed LED strobes synchronized to camera exposure, requiring precise current control and rapid on/off switching. IC Role / Device Role / Timing Role: LT3797ILXE#PBF operates in buck-boost mode to drive constant-current LED arrays from variable 12–24V industrial rails, with TG-driven PMOS disconnect enabling µs-level strobe blanking. Use Value: Achieves sub-microsecond LED turn-off via TG drivers - eliminating motion blur in 10k+ fps imaging applications without compromising peak current accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3797EUKG#PBF | Same die, QFN-52 package (7mm × 8mm), θJA = 28°C/W, MSL 1 - higher thermal resistance than LQFP variant. | Better suited for space-constrained PCBs where exposed-pad thermal path is optimized; less ideal for high-power density layouts requiring lower θJA. | Select when board real estate is limited and thermal vias under QFN pad can be maximized - avoid if ambient temperature exceeds 85°C without forced airflow. |
| LT3761EFE#PBF | Single-channel boost LED controller, 60V switch rating, no integrated INTVCC, no TG drivers - lacks multi-channel integration and PMOS disconnect capability. | Requires three separate ICs plus external bias supplies to replicate LT3797ILXE#PBF functionality - increases component count and layout complexity. | Consider only for cost-sensitive, low-channel-count designs where independent thermal management per channel is preferred and BOM count is secondary. |
Compared with LT3797EUKG#PBF, the LT3797ILXE#PBF offers lower thermal resistance (19°C/W vs. 28°C/W) and LQFP packaging compatible with standard reflow profiles; versus LT3761EFE#PBF, it delivers true triple-channel integration with shared oscillator synchronization and unified fault reporting - reducing system-level timing jitter and diagnostic overhead.
Availability
LT3797ILXE#PBF is available at Aetrix Electronics and suitable for automotive headlamp control, RGB stage lighting, outdoor digital billboards, and industrial machine vision lighting requiring stable component supply across extended temperature and voltage ranges.
Supply support for LT3797ILXE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets with precision power management solutions.
The LT3797 product line was designed specifically for multi-string LED lighting systems requiring topology flexibility, high-side current sensing, and robust fault management - targeting automotive exterior lighting and professional display applications.
FAQ
What is the maximum input voltage transient tolerance for the LT3797ILXE#PBF?
The LT3797ILXE#PBF withstands input voltage transients up to 60V while maintaining functional operation. Its internal VIN overvoltage lockout triggers at 41V (typical) to protect downstream circuitry, and the device automatically resets soft-start and disables all channels during overvoltage events. This makes the LT3797ILXE#PBF suitable for automotive 12V/24V systems subject to load-dump conditions defined in ISO 7637-2.
How does the LT3797ILXE#PBF support high-side LED current sensing?
The LT3797ILXE#PBF supports high-side current sensing via dedicated ISP1–3 and ISN1–3 pins, which tolerate 0V to 100V common-mode voltage. This allows placement of the current sense resistor on the LED string anode side - essential for boost topologies where the cathode is grounded. The differential amplifier rejects common-mode noise, ensuring accurate current regulation independent of output voltage.
Can the LT3797ILXE#PBF operate in buck mode for all three channels?
Yes, the LT3797ILXE#PBF supports buck, boost, buck-boost, SEPIC, and flyback configurations per channel. For buck operation, connect the ISP pin to the LED string anode, ISN to the sense resistor low side, and configure FBH to enable voltage loop regulation if needed. Each channel's topology is selected independently via external component choice - no configuration register or firmware required.
What is the purpose of the TG1–3 pins on the LT3797ILXE#PBF?
The TG1–3 pins on the LT3797ILXE#PBF are top-gate drivers that output inverted PWM signals to control external P-channel MOSFETs placed between ISP and the LED string. During fault conditions (open-LED, overvoltage), TG drivers pull high to disconnect LEDs - providing short-circuit protected boost capability and preventing damage. Each TG pin operates with 6.5V gate drive swing referenced to ISP.
Does the LT3797ILXE#PBF require external compensation components per channel?
Yes, the LT3797ILXE#PBF requires external RC networks from VC1–3 pins to GND for loop compensation. Each VC pin connects to the error amplifier output and must be stabilized with a series resistor and capacitor to ensure stable current regulation across line/load/temperature variations. The values depend on chosen topology and output filter characteristics - Analog Devices provides design equations and example values in the LT3797 datasheet.
LT3797ILXE#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)
LT3797ILXE#PBF FAQ
1.How can I place an order for LT3797ILXE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3797ILXE#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 LT3797ILXE#PBF reliable?
The price and inventory of LT3797ILXE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3797ILXE#PBF is usually 5 days.
3.What payment methods are accepted for LT3797ILXE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3797ILXE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3797ILXE#PBF?
LT3797ILXE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3797ILXE#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 LT3797ILXE#PBF?
For technical support, including LT3797ILXE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3797ILXE#PBF requirements.
6.How does Aetrix verify that LT3797ILXE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3797ILXE#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 LT3797ILXE#PBF meets industry standards.
7.What is the process for return or replacement of LT3797ILXE#PBF?
All LT3797ILXE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3797ILXE#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 LT3797ILXE#PBF part is unused and in its original packaging.
Return procedure for LT3797ILXE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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