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Analog Devices Inc. LT3965EFE-1#PBF
- Part No.:
- LT3965EFE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3965EFE-1#PBF.pdf
- Description:
- IC LED DRVR RGLTR I2C 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,011
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Product details
Overview
LT3965EFE-1#PBF from Analog Devices is an automotive-grade 8-channel LED bypass switch IC for precision dimming of high-voltage LED strings using a common current source. It integrates eight 17V/330mΩ floating-source NMOS switches, supports I²C multidrop (16-device bus), delivers 256:1 digital PWM dimming with logarithmic fade, and reports open/shorted LED faults per channel. It is used in adaptive automotive headlight clusters requiring flicker-free, independent per-LED control.
For engineers reviewing the LT3965EFE-1#PBF datasheet, LT3965EFE-1#PBF pinout, LT3965EFE-1#PBF application, or LT3965EFE-1#PBF equivalent, key selection criteria include VIN operating range (8–60V), per-channel fault threshold programmability (VOTH/VSTH), fade-enabled 11-bit transition resolution, AEC-Q100 qualification, and TSSOP-28 thermal performance with exposed GND pad.
Technical Context
The LT3965EFE-1#PBF implements a parallel/series-configurable 8-switch matrix architecture where each DRN–SRC pair operates as a floating-source NMOS bypass path across one or more LEDs. Its I²C interface supports both single-channel (SCMODE) and all-channel (ACMODE) writes with programmable 4-bit address select pins (ADDR[4:1]), enabling up to 16 devices on one bus.
Fault detection is per-channel and configurable: open-LED thresholds (VOTH) are set to 4.5V/9V/13.5V/18V (default 9V for LT3965-1 variant), while shorted-LED thresholds (VSTH) scale with LEDREF voltage (0–4V input) to detect 1–4 shorted LEDs. PWM dimming uses either internal oscillator (RTCLK resistor-programmed) or external clock, both divided by 2048 for final frequency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 8V to 60V - supports wide-input LED drivers including automotive battery-supplied buck/boost topologies. |
| Switch RDS(on) | 330 mΩ max - enables low-loss bypass of up to 17V LED segments without significant voltage drop or heating. |
| PWM Dimming Resolution | 256:1 (8-bit) with optional 11-bit logarithmic fade - ensures smooth, perceptually linear brightness transitions across full range. |
| I²C Address Options | 16 unique addresses via ADDR[4:1] - allows scalable multi-device control in large display or lighting systems without address conflict. |
| Open LED Threshold (Default) | 9 V (VOTH[1:0]=01) - matches typical forward voltage of 2–3 white LEDs in series, enabling reliable open-circuit detection. |
| Operating Temp Range | –40°C to +125°C junction - qualified per AEC-Q100 Grade 1, suitable for under-hood automotive LED headlight modules. |
| Fault Reporting | Per-channel open/shorted LED + overtemperature (≥170°C) - enables system-level diagnostics and graceful failover without MCU polling overhead. |
Pinout & Package
LT3965EFE-1#PBF is housed in a 28-lead plastic TSSOP package with exposed GND pad (Pin 29), requiring soldering to PCB ground plane for thermal and electrical integrity. θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | High-side power supply input | Supplies all 8 channel switches and fault detectors; must exceed SRC voltage by ≥7.1V for proper operation. |
| EN/UVLO | Enable and undervoltage lockout input | 1.24V falling threshold with programmable hysteresis; controls POR reset and shutdown IQ <1µA. |
| ALERT | Open-drain fault indicator output | Pulled low on any channel open/short fault or overtemperature; supports I²C alert response address (ARA) protocol. |
| RTCLK | Oscillator programming / external clock input | Resistor-to-GND sets internal PWM clock; external 2.5MHz clock overrides it; dimming frequency = fCLK/2048. |
| LEDREF | Reference voltage for shorted-LED detection | 0–4V input scales VSTH thresholds; 0V sets fixed 1V short threshold; >4V clamps internal reference to 4V. |
| DRN[8:1] | Drain terminals of 8 NMOS switches | Floating; connect to LED+ node or string segments; each pairs with corresponding SRC pin to form bypass path. |
| SRC[8:1] | Source terminals of 8 NMOS switches | Floating; connect to LED– or intermediate nodes; must be ≤VIN – 7.1V for valid switch conduction. |
| ADDR[4:1] | I²C address configuration inputs | 4-bit binary address; internal 500kΩ pull-ups default to "1111"; tie to GND to overwrite individual bits. |
| VDD | Digital logic and I²C interface supply | 2.7–5.5V; defines SCL/SDA logic levels; I²C remains active even during EN/UVLO shutdown. |
| SDA/SCL | I²C bidirectional data/clock | Standard-compliant 400kHz interface; level-shifted to VDD; supports repeated start, random register access, and ARA. |
Key Features
| Feature | Design Value |
|---|---|
| Eight independent 17V/330mΩ NMOS switches | Enables flexible matrix routing-parallel connection for higher current handling, series for extended voltage tolerance across multi-LED segments. |
| Programmable per-channel open/short LED fault detection | Eliminates need for external sense resistors or comparators; VOTH/VSTH registers allow tuning to specific LED string configurations and aging profiles. |
| Flicker-free 256:1 PWM dimming with logarithmic fade | 11-bit fade resolution maps to human eye's log luminance response, avoiding visible stepping during brightness ramping in automotive ADAS lighting. |
| AEC-Q100 Grade 1 qualification (–40°C to +125°C) | Validated for under-hood deployment; includes HTOL, TC, ESD, and EM test reports-no additional qualification required for automotive OEM programs. |
| I²C multidrop support with 16-address capability | Reduces MCU GPIO count and simplifies firmware architecture in large-scale systems like dynamic rear combination lamps (DRCL) or stadium displays. |
Applications
| Automotive Adaptive Headlights | Large-Scale LED Video Displays |
|---|---|
|
Use Scenario: Pixel-level beam shaping in matrix LED headlamps, where individual LEDs are selectively bypassed to create dark zones (e.g., no-glare high-beam). IC Role / Device Role / Timing Role: Bypass switch controller managing real-time on/off/fade states of 8 LED sub-strings per IC; synchronized via I²C to central vision processor. Use Value: Enables <100ms dynamic beam cutoff without mechanical shutters; leverages default 9V open-LED threshold to maintain reliability across temperature and LED VF drift. |
Use Scenario: High-resolution outdoor LED signage with thousands of individually controllable pixels, requiring uniform dimming and fault resilience. IC Role / Device Role / Timing Role: Localized LED string manager per module; handles 8-channel dimming, open-circuit detection, and ALERT-driven fault reporting to central controller. Use Value: Reduces system-level diagnostic latency by 90% vs. scan-based monitoring; 16-device I²C addressing supports modular tile expansion without bus redesign. |
| Automated Camera Flash Systems | RGBW Architectural Lighting |
|
Use Scenario: Multi-segment flash units in industrial machine vision cameras, where precise timing and intensity control prevent motion blur. IC Role / Device Role / Timing Role: High-speed PWM dimmer with <0.5µs switch transition time; fade mode eliminates strobing artifacts during ramp-up/down. Use Value: Achieves ±1% intensity repeatability across 10,000+ flash cycles; internal oscillator eliminates need for external timing crystal, reducing BOM count. |
Use Scenario: Tunable white and color-mixed architectural fixtures using separate R/G/B/W LED strings with independent thermal derating. IC Role / Device Role / Timing Role: Per-string bypass controller supporting independent fade curves per channel; LEDREF pin enables dynamic short-threshold adjustment as color mix changes. Use Value: Maintains consistent CCT across dimming range by synchronizing RGBW fade timing; shorted-LED detection prevents color shift due to single-LED failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED bypass switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EFE#PBF | Same pinout and feature set, but initializes all switches OFF (LEDs ON) at POR; default VOTH = 18V vs. 9V. | Better suited for applications requiring default illumination (e.g., backup lamps) rather than default off (e.g., glare-free headlights). | Select LT3965EFE#PBF when system requires fail-safe "on" state at power-up and higher open-LED detection threshold. |
| TLC5940QPWPRQ1 | 16-channel constant-current LED driver (not bypass switch); no open/short fault reporting; requires external current source. | Designed for low-voltage, current-sink LED arrays (≤17V); lacks high-side VIN capability and fault intelligence of LT3965EFE-1#PBF. | Choose TLC5940QPWPRQ1 only for cost-sensitive, non-automotive designs with simple constant-current topology and no fault diagnostics needed. |
Compared with LT3965EFE#PBF, the LT3965EFE-1#PBF offers lower default open-LED threshold (9V vs. 18V) and POR-on state ideal for adaptive beam control, while TLC5940QPWPRQ1 provides higher channel count but no bypass architecture or integrated fault detection-making it unsuitable for high-VIN, fault-resilient automotive LED systems.
Availability
LT3965EFE-1#PBF is available at Aetrix Electronics and suitable for automotive LED headlight clusters, large-format LED displays, and automated camera flash equipment requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for LT3965EFE-1#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3965/LT3965-1 product line was designed specifically for intelligent, fault-aware LED string management in demanding automotive and industrial lighting-emphasizing robustness, programmability, and system-level diagnostics over basic dimming.
FAQ
What is the default power-on behavior of the LT3965EFE-1#PBF?
The LT3965EFE-1#PBF powers up with all eight NMOS switches ON (bypassing LEDs, so LEDs are OFF) and open-LED threshold (VOTH) set to 9V by default. This POR state is hard-coded in the device and differs from the LT3965EFE#PBF, which defaults to all switches OFF and VOTH = 18V. The LT3965EFE-1#PBF's default behavior supports fail-safe "off" operation in glare-control headlight systems.
How does the LT3965EFE-1#PBF detect a shorted LED condition?
The LT3965EFE-1#PBF detects shorted LEDs by comparing the voltage at DRN relative to SRC against a programmable threshold (VSTH), which scales with the voltage applied to the LEDREF pin. With LEDREF = 0V, VSTH defaults to 1V; with LEDREF = 3V, VSTH becomes 4V, 7V, 10V, or 10.4V depending on VSTH[1:0] register setting. This allows precise detection of 1–4 shorted LEDs in a segment without external components.
Can the LT3965EFE-1#PBF operate with a 3.3V I²C bus while powered from 48V VIN?
Yes. The LT3965EFE-1#PBF separates logic and power domains: VDD (2.7–5.5V) supplies the I²C interface and defines SCL/SDA logic levels, while VIN (8–60V) powers the NMOS switches and fault circuitry. A 3.3V microcontroller can directly drive SDA/SCL when VDD = 3.3V, regardless of VIN = 48V. No level-shifting is required between MCU and LT3965EFE-1#PBF I²C lines.
What thermal considerations apply to the LT3965EFE-1#PBF in continuous 330mΩ switch operation?
The LT3965EFE-1#PBF's 28-lead TSSOP package features an exposed GND pad (Pin 29) that must be soldered to a PCB thermal plane. With θJC = 10°C/W, sustained 500mA through a 330mΩ switch generates ~83mW per channel. For full 8-channel operation, thermal design must ensure junction temperature stays ≤125°C-achievable with ≥2 cm² copper area and 2+ internal ground layers under the IC.
Does the LT3965EFE-1#PBF support synchronized dimming across multiple devices?
Yes. Multiple LT3965EFE-1#PBF devices can be synchronized using a shared external clock on the RTCLK pin. When driven by the same 2.5MHz clock source, all devices divide by 2048 to produce identical PWM frequencies and phase-aligned dimming cycles-critical for flicker-free operation in large displays or coordinated headlight zones. Internal oscillator mode does not guarantee synchronization.
LT3965EFE-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- 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
LT3965EFE-1#PBF FAQ
1.How can I place an order for LT3965EFE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3965EFE-1#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 LT3965EFE-1#PBF reliable?
The price and inventory of LT3965EFE-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3965EFE-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3965EFE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3965EFE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3965EFE-1#PBF?
LT3965EFE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3965EFE-1#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 LT3965EFE-1#PBF?
For technical support, including LT3965EFE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3965EFE-1#PBF requirements.
6.How does Aetrix verify that LT3965EFE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3965EFE-1#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 LT3965EFE-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3965EFE-1#PBF?
All LT3965EFE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3965EFE-1#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 LT3965EFE-1#PBF part is unused and in its original packaging.
Return procedure for LT3965EFE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3965EFE-1#PBF Tags
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