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Analog Devices Inc. LT3965IFE-1#TRPBF
- Part No.:
- LT3965IFE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3965IFE-1#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR I2C 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,595
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Product details
Overview
LT3965IFE-1#TRPBF from Analog Devices is an automotive-grade 8-channel LED bypass switch IC for precision PWM dimming of high-voltage LED strings using a common current source. It integrates eight 17V/330mΩ NMOS switches, supports I²C multidrop (16-device bus), delivers 256:1 digital PWM dimming with logarithmic fade transition, and reports open/shorted LED faults per channel - deployed in adaptive automotive headlight clusters and RGBW lighting systems.
For engineers reviewing the LT3965IFE-1#TRPBF datasheet, LT3965IFE-1#TRPBF pinout, LT3965IFE-1#TRPBF application, or LT3965IFE-1#TRPBF equivalent, key selection considerations include its AEC-Q100 qualification, VIN range up to 60V, programmable open LED thresholds (4.5V–18V), 11-bit fade resolution, and initialization-on-power-up with all switches ON (LEDs OFF) - critical for fail-safe lighting control architectures.
Technical Context
The LT3965IFE-1#TRPBF implements a floating-source NMOS switch matrix architecture where each of eight independent channels operates with DRN–SRC voltage tolerance up to 25V and supports series/parallel bypass configurations. Its fault detection logic uses dual-programmable thresholds (VOTH/VSTH) referenced to LEDREF to distinguish open-circuit (e.g., 9V default for LT3965-1) and shorted-LED conditions across multi-LED segments.
Dimming control is executed via I²C-configurable SCMREG registers, enabling per-channel selection of constant ON/OFF, PWM-only, or logarithmic fade modes. Fade transitions use 11-bit internal arithmetic (CF = 1.0625/0.9375) to generate up to 100-step brightness ramps synchronized to RTCLK-derived 2048-cycle PWM frames - eliminating visible flicker while matching human photopic response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 8V to 60V - supports wide-input LED drivers including buck-based 40V+ automotive supplies. |
| Switch RDS(on) | 330 mΩ max - enables low-loss bypass of up to 17V LED drops without external heatsinking. |
| PWM Dimming Resolution | 256:1 (8-bit) with 11-bit fade interpolation - provides smooth, perceptually linear brightness transitions. |
| Open LED Threshold (POR) | 9 V (VOTH[1:0] = "01") - factory-default setting for LT3965-1 variant ensures immediate fault detection at startup. |
| I²C Address Options | 16 unique addresses via ADDR[4:1] pins - allows scalable multidrop control of multiple LT3965IFE-1#TRPBF devices on one bus. |
| Operating Temp Range | –40°C to +125°C - qualified per AEC-Q100 Grade 1 for under-hood and headlamp module deployment. |
| Fault Reporting | Per-channel open/shorted LED + overtemperature (≥170°C) - asserted via open-drain ALERT pin for system-level interrupt handling. |
Pinout & Package
LT3965IFE-1#TRPBF is housed in a 28-lead TSSOP package with exposed pad (Pin 29 = GND), θJC = 10°C/W. The package requires soldering of the exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | High-side power input | Supplies all 8 channel switches and fault detectors; must exceed SRC by ≥7.1V for reliable bypass operation. |
| EN/UVLO | Enable & undervoltage lockout | 1.24V falling threshold with programmable hysteresis; resets registers on rising edge and disables switches when <0.4V. |
| ALERT | Open-drain fault indicator | Pulled low on open LED, shorted LED, or overtemperature; deasserted after Alert Response Address (ARA) read or I²C clear. |
| RTCLK | Oscillator programming / clock input | Accepts resistor-to-GND (e.g., 28kΩ → 500Hz PWM) or external 2.5MHz clock; dimming frequency = input / 2048. |
| LEDREF | Shorted-LED reference input | Sets VSTH base threshold (1V, VLEDREF+1V, etc.); fixed at 4V if >4V applied; must not float. |
| VDD | Logic supply & I²C reference | 2.7V–5.5V input; defines SCL/SDA logic levels; I²C remains active even during EN/UVLO shutdown. |
| SCL / SDA | I²C serial interface | Standard 400kHz bus interface with VDD-scaled thresholds; supports random register access and multidrop addressing. |
| ADDR[4:1] | Hardware address select | 4-pin binary input (pulled up internally to VDD); sets device address (010xxxxx or 101xxxxx) for up to 16 devices on one bus. |
| DRN[8:1] | Switch drain terminals | Floating NMOS drains; connect to LED+ side of string; tie to VDD via 100kΩ if unused. |
| SRC[8:1] | Switch source terminals | Floating NMOS sources; connect to LED– side; must be ≤VIN – 7.1V; tie to GND if unused. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade 1 qualification | Validated for automotive ambient temperatures (–40°C to +125°C) and lifetime reliability in headlamp modules. |
| Programmable open LED detection | Four selectable thresholds (4.5V/9V/13.5V/18V) per channel - configurable via VOTH[1:0] bits to match LED string VF. |
| Logarithmic fade transition | 11-bit internal calculation (CF = 1.0625/0.9375) generates perceptually smooth brightness ramps without MCU intervention. |
| Crowbar protection clamping | 22V–25V clamp between DRN–SRC during overvoltage events - prevents destructive voltage spikes across bypassed LEDs. |
| Per-channel shorted LED detection | VSTH programmable from 1V to 13.7V (based on LEDREF) - discriminates single vs. multi-LED shorts in segmented strings. |
| Low quiescent current | 1.3mA VDD IQ (I²C idle) and ≤1µA shutdown IQ - minimizes standby power in always-on lighting systems. |
Applications
| Automotive Adaptive Headlights | Large-Scale LED Video Displays |
|---|---|
|
Use Scenario: Dynamic beam shaping in LED-based automotive headlamp modules with pixel-level control. IC Role / Device Role / Timing Role: Bypasses individual LEDs or LED segments in high-current strings powered by constant-current buck drivers. Use Value: Enables precise, flicker-free dimming of up to 8 zones per IC with AEC-Q100 reliability and real-time open/short fault reporting. |
Use Scenario: Brightness calibration and failure mitigation in outdoor LED billboards and stadium displays. IC Role / Device Role / Timing Role: Independently manages current path around defective LEDs in long串联 strings using common-current topology. Use Value: Maintains display uniformity and uptime by isolating failed LEDs while preserving adjacent segment operation. |
| Automated Camera Flash Systems | RGBW Architectural Lighting |
|
Use Scenario: High-speed, synchronized flash intensity control in industrial machine vision and medical imaging equipment. IC Role / Device Role / Timing Role: Provides sub-millisecond PWM dimming with fade transition to match exposure timing and reduce thermal stress. Use Value: Delivers repeatable, calibrated flash output across varying ambient temperatures with no visible stepping artifacts. |
Use Scenario: Precise white-point tuning and color mixing in tunable-white and full-color architectural LED fixtures. IC Role / Device Role / Timing Role: Independently dims red, green, blue, and white LED strings driven by shared constant-current sources. Use Value: Achieves CRI >90 and Δu'v' <0.003 through synchronized 256-step dimming with logarithmic fade across all channels. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED bypass switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965IFE#TRPBF | Initial POR state: all switches OFF (LEDs ON); default open LED threshold = 18V (VOTH[1:0]="11"). | Suitable for systems requiring default illumination at power-up; lacks LT3965-1's fail-safe OFF-at-start behavior. | Select LT3965IFE#TRPBF when default LED-on operation is required and open LED detection at higher voltages is needed. |
| MAX16832ATL+ | 4-channel, 40V-rated switch; no fade transition; analog/digital dimming only; no I²C multidrop support. | Limited to simpler, lower-channel-count lighting systems without per-channel fault reporting or logarithmic ramping. | Choose MAX16832ATL+ for cost-sensitive, non-automotive designs needing basic bypass control without advanced diagnostics. |
Compared with LT3965IFE#TRPBF, the LT3965IFE-1#TRPBF offers safer default-off behavior for automotive fail-operational requirements, while the MAX16832ATL+ trades channel count, fade capability, and bus scalability for lower BOM cost and simpler control.
Availability
LT3965IFE-1#TRPBF is available at Aetrix Electronics and suitable for automotive headlight clusters, large LED displays, and automated camera flash equipment requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for LT3965IFE-1#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT3965IFE-1#TRPBF belongs to Analog Devices' Power by Linear™ LED driver portfolio, engineered specifically for robust, high-reliability LED current steering in safety-critical automotive lighting and demanding commercial display applications.
FAQ
What is the power-on reset (POR) behavior of the LT3965IFE-1#TRPBF?
The LT3965IFE-1#TRPBF initializes all eight switches to the ON state (bypassing LEDs, resulting in LEDs OFF) upon EN/UVLO rising edge. Its default open LED threshold is set to 9V (VOTH[1:0] = "01"), and all SCMREG registers load 0xFF (full dimming). This fail-safe POR state ensures no unintended illumination at system startup - a critical requirement for automotive headlamp compliance.
How does the LT3965IFE-1#TRPBF implement logarithmic fade transition?
The LT3965IFE-1#TRPBF calculates fade steps using 11-bit internal arithmetic: DVNEXT = DVPRESENT × CF, where CF = 1.0625 (fade up) or 0.9375 (fade down). Each step executes over one full 2048-RTCLK-cycle PWM frame, generating up to 100 perceptually smooth transitions from minimum to maximum brightness without MCU overhead.
Can the LT3965IFE-1#TRPBF detect shorted LEDs in multi-LED segments?
Yes. By applying a reference voltage (0–4V) to LEDREF, the LT3965IFE-1#TRPBF configures VSTH to detect 1-, 2-, 3-, or 4-LED shorts via VSTH[1:0] bits. For example, with LEDREF = 3V and VSTH[1:0] = "11", the threshold becomes 10.4V - enabling discrimination between partial and full segment shorts in long LED strings.
What is the role of the RTCLK pin on the LT3965IFE-1#TRPBF?
The RTCLK pin serves dual functions: (1) it accepts a resistor to GND (e.g., 28kΩ) to program the internal oscillator for 500Hz PWM dimming, or (2) it accepts an external 2.5MHz clock signal to override the oscillator. In both cases, final PWM frequency = RTCLK input frequency ÷ 2048 - ensuring precise, jitter-free dimming synchronization.
Does the LT3965IFE-1#TRPBF require external components for basic operation?
Yes. Minimum external components include: 1µF VIN bypass capacitor, 0.1µF VDD decoupling capacitor, pull-up resistors on ADDR[4:1] (if not grounded), and a resistor on RTCLK (if using internal oscillator). The EN/UVLO pin typically requires a PNP level shifter network to ensure enablement only when VIN exceeds SRC by ≥7.1V - critical for safe switch operation.
LT3965IFE-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 8
- Voltage - Supply (Min):
- 8V
- Voltage - Supply (Max):
- 60V
- Voltage - Output:
- -
- Current - Output / Channel:
- 500mA
- Frequency:
- -
- Dimming:
- I2C, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT3965IFE-1#TRPBF FAQ
1.How can I place an order for LT3965IFE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3965IFE-1#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 LT3965IFE-1#TRPBF reliable?
The price and inventory of LT3965IFE-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3965IFE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3965IFE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3965IFE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3965IFE-1#TRPBF?
LT3965IFE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3965IFE-1#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 LT3965IFE-1#TRPBF?
For technical support, including LT3965IFE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3965IFE-1#TRPBF requirements.
6.How does Aetrix verify that LT3965IFE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3965IFE-1#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 LT3965IFE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3965IFE-1#TRPBF?
All LT3965IFE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3965IFE-1#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 LT3965IFE-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3965IFE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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