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Analog Devices Inc. LT3965EFE#PBF
- Part No.:
- LT3965EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3965EFE#PBF.pdf
- Description:
- IC LED DRVR RGLTR I2C 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,108
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Product details
Overview
LT3965EFE#PBF from Analog Devices is an 8-channel LED bypass switching IC for precision dimming of individual LEDs in high-voltage strings using a common current source. It integrates eight floating-source 17V/330mΩ NMOS switches, supports I²C multidrop (16-device bus), delivers 256:1 digital PWM dimming with optional logarithmic fade transition, and reports open/shorted LED faults per channel - deployed in automotive headlight clusters and RGBW lighting systems.
For engineers reviewing the LT3965EFE#PBF datasheet, LT3965EFE#PBF pinout, LT3965EFE#PBF application, or LT3965EFE#PBF equivalent, key selection criteria include VIN 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#PBF implements independent per-channel control logic with dual-mode PWM dimming: immediate step-change or logarithmic fade across up to 100 steps. Each channel's switch operates as a floating-source NMOS with DRN–SRC voltage rating up to 25V and crowbar protection clamping at 22–25V during overcurrent events.
Fault detection is fully programmable: open-LED thresholds (4.5V/9V/13.5V/18V) and shorted-LED thresholds (1V to 13.7V, dependent on LEDREF and VSTH[1:0] bits) are set via I²C registers. EN/UVLO provides accurate 1.24V falling threshold with externally adjustable hysteresis for VIN–VLED+ monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 8V to 60V - powers all 8 bypass switches and fault detectors; requires ≥7.1V headroom above SRC voltage for reliable operation. |
| Switch On-Resistance | 330 mΩ - enables low-loss current shunting around individual LEDs in high-current strings without significant self-heating. |
| PWM Dimming Resolution | 256:1 (8-bit) - supports fine-grained brightness control; fade mode extends effective resolution to 11-bit logarithmic transitions. |
| I²C Address Options | 16 unique addresses - configured via ADDR1–ADDR4 pins; allows daisy-chained control of multiple LT3965EFE#PBF devices on one bus. |
| Open LED Thresholds | Programmable to 4.5V / 9V / 13.5V / 18V - default POR state is 9V for LT3965-1 variant; enables robust fault detection across varied LED VF stacks. |
| Operating Temperature | –40°C to +125°C - specified and guaranteed for industrial and automotive applications; junction-limited lifetime derating applies above 125°C. |
| AEC-Q100 Grade | Qualified - meets stress test requirements for automotive electronics; LT3965EFE#PBF is the standard-grade version (non-automotive suffix). |
Pinout & Package
LT3965EFE#PBF is housed in a 28-lead plastic TSSOP package (FE) with exposed GND pad (Pin 29) requiring PCB soldering for thermal and electrical integrity. θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 2) | High-side power input | Supplies all 8 channel switches and fault circuitry; must exceed SRC voltage by ≥7.1V for valid bypass operation. |
| EN/UVLO (Pin 3) | Enable & undervoltage lockout | 1.24V falling threshold detects insufficient VIN–VLED+ margin; rising hysteresis programmable via external resistor. |
| ALERT (Pin 4) | Open-drain fault indicator | Pulled low on open LED, shorted LED, or overtemperature (≥170°C); supports I²C alert response address (ARA) protocol. |
| RTCLK (Pin 8) | Oscillator clock interface | Accepts external clock (≤2.5MHz) or sets internal oscillator frequency (e.g., 28kΩ → ~500Hz PWM output after /2048 division). |
| LEDREF (Pin 13) | Shorted-LED reference input | Sets base threshold for shorted-LED detection; VSTH = 1V, VLEDREF+1V, 2×VLEDREF+1V, or 3×VLEDREF+1V depending on register setting. |
| DRN1–DRN8 (Pins 14–21, 23–24, 26–27) | Drain terminals (8 channels) | Floating NMOS drain nodes; connect to LED string anode side; each rated for 60V max and 25V DRN–SRC differential. |
| SRC1–SRC8 (Pins 15–22, 25, 28) | Source terminals (8 channels) | Floating NMOS source nodes; connect to LED string cathode side; require VIN ≥ SRC + 7.1V for proper switching. |
| GND (Pin 29) | Thermal & signal ground | Exposed pad - must be soldered to PCB ground plane for thermal dissipation (θJC = 10°C/W) and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Eight independent floating-source NMOS switches | Each rated 17V/330mΩ - enables flexible series/parallel bypass topologies for multi-LED segments without shared-source constraints. |
| Per-channel programmable open/short LED fault detection | Four selectable VOTH thresholds (4.5–18V) and four VSTH configurations (1–13.7V) - adapts to varying LED stack voltages and failure modes. |
| Logarithmic fade transition dimming | 11-bit resolution with CF = 1.0625 (fade-up) or 0.9375 (fade-down) - matches human eye luminance perception and eliminates visible stepping. |
| I²C multidrop with 16-address capability | ADDR1–ADDR4 pins support hardware-configurable addresses (010xxxxx / 101xxxxx) - eliminates software address conflicts in large LED arrays. |
| Integrated crowbar protection | Clamps DRN–SRC to 22–25V at 500mA fault current - prevents overvoltage damage during open-LED events while maintaining string continuity. |
Applications
| Automotive LED Headlight Clusters | Large LED Displays |
|---|---|
|
Use Scenario: Adaptive driving beam (ADB) systems requiring independent dimming of 8+ LED segments per headlight module. IC Role / Device Role / Timing Role: Bypass switch controller that shunts current around individual LEDs under microcontroller I²C command, enabling pixel-level beam shaping. Use Value: Enables AEC-Q100-compliant, flicker-free dimming with real-time fault reporting (open/short LED) to maintain functional safety compliance (ISO 26262 ASIL-B). |
Use Scenario: Outdoor video billboards with high-density RGB LED modules requiring uniform brightness scaling across thousands of pixels. IC Role / Device Role / Timing Role: Per-string dimming enabler that replaces analog current sinks with digitally controlled NMOS bypass paths synchronized via shared I²C bus. Use Value: Delivers 256:1 PWM resolution and fade transition to eliminate visible brightness jumps during content transitions, improving perceived image quality. |
| Automated Camera Flash Equipment | RGBW Color Mixing Lighting |
|
Use Scenario: High-speed machine vision systems needing precise, repeatable flash intensity control across multiple LED banks. IC Role / Device Role / Timing Role: Fast-switching bypass driver that modulates LED current on sub-millisecond timescales using internal 500Hz PWM clock (RTCLK = 28kΩ). Use Value: Achieves <1µs switch transition time and crowbar-protected fault handling - ensures consistent flash output even during thermal or wiring faults. |
Use Scenario: Architectural tunable-white and full-color luminaires where R/G/B/W LED strings must be independently dimmed to achieve target CCT and chromaticity. IC Role / Device Role / Timing Role: Independent channel controller allowing simultaneous but non-identical dimming profiles per color channel via I²C register writes. Use Value: Supports per-channel fade timing and logarithmic dimming curves - critical for smooth, non-jarring white-point transitions and saturated color blending. |
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#PBF | Same silicon, extended –40°C to +125°C guaranteed temperature range (I-grade vs E-grade). | Required for designs needing full-specification validation across full automotive/junction temp range. | Select LT3965IFE#PBF when production validation requires guaranteed parametric performance at –40°C and +125°C, not just design assurance. |
| LT3965EFE-1#PBF | Different power-on reset (POR) state: all switches initialized ON (LEDs off) vs LT3965EFE#PBF's OFF (LEDs on); VOTH default = 9V instead of 18V. | Suitable for fail-safe "dark-on-power-up" systems (e.g., emergency signage) where default LED-off is mandatory. | Choose LT3965EFE-1#PBF only if system architecture requires default-bypass behavior and lower open-LED threshold at startup. |
Compared with LT3965EFE#PBF, the LT3965IFE#PBF offers guaranteed operation across the full industrial temperature range, while the LT3965EFE-1#PBF changes default switch state and fault threshold - both require firmware adaptation but provide distinct safety or qualification advantages.
Availability
LT3965EFE#PBF is available at Aetrix Electronics and suitable for automotive LED headlight clusters, large-format LED displays, and RGBW color-tuning luminaires requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT3965EFE#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 leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision signal chain and power management applications.
The LT3965 product line is designed for intelligent, fault-aware LED current steering in high-reliability lighting systems - targeting automotive, industrial, and architectural applications where per-LED control, diagnostics, and AEC-Q100 compliance are essential.
FAQ
What is the default power-on behavior of the LT3965EFE#PBF?
The LT3965EFE#PBF initializes all eight NMOS switches in the OFF state (i.e., LEDs remain illuminated) upon power-on reset. Its default open-LED threshold (VOTH) is set to 18V, and shorted-LED threshold (VSTH) defaults to 1V when LEDREF = 0V. This behavior distinguishes it from the LT3965EFE-1#PBF, which powers up with all switches ON. The LT3965EFE#PBF retains these defaults until modified via I²C register writes.
Does the LT3965EFE#PBF support external clock synchronization for PWM dimming?
Yes, the LT3965EFE#PBF supports external clock synchronization via the RTCLK pin. When driven with a clean square wave (VIH ≥ 1.5V, VIL ≤ 0.4V, ≤2.5MHz), the device uses the external clock frequency divided by 2048 as its PWM dimming frequency - enabling precise inter-device timing alignment in multi-IC LED systems. Internal oscillator mode (resistor-programmed) remains active only when RTCLK is not actively driven.
How does the LT3965EFE#PBF handle open-LED faults during operation?
When an open-LED fault is detected - determined by DRN–SRC voltage exceeding the programmed VOTH threshold - the LT3965EFE#PBF automatically turns ON the corresponding channel's NMOS switch to bypass the faulty LED and maintain string continuity. The ALERT pin is pulled low, and the fault status is latched in the OLFREG register until cleared by I²C write. PWM dimming for that channel halts until the fault is resolved or manually reset.
Can the LT3965EFE#PBF drive LEDs directly, or does it require an external current source?
The LT3965EFE#PBF does not source or sink LED current; it functions exclusively as a bypass switch. It requires an external constant-current LED driver (e.g., LT3955 buck LED controller) to establish the string current. The LT3965EFE#PBF shunts current around selected LEDs via its eight NMOS channels - enabling dimming without altering the main current source's regulation point or efficiency.
What thermal considerations apply to the LT3965EFE#PBF in high-power LED applications?
The LT3965EFE#PBF's exposed pad (Pin 29) must be soldered to a PCB ground plane to achieve θJC = 10°C/W. With 330mΩ RDS(on) and typical 100mA per channel, power dissipation per switch is ~3.3mW - negligible thermally. However, under fault conditions (e.g., crowbar clamping at 25V/500mA), localized heating exceeds 12.5W; adequate copper area and thermal vias are mandatory to sustain safe junction temperatures below 125°C.
LT3965EFE#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#PBF FAQ
1.How can I place an order for LT3965EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3965EFE#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#PBF reliable?
The price and inventory of LT3965EFE#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#PBF is usually 5 days.
3.What payment methods are accepted for LT3965EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3965EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3965EFE#PBF?
LT3965EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3965EFE#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#PBF?
For technical support, including LT3965EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3965EFE#PBF requirements.
6.How does Aetrix verify that LT3965EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3965EFE#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#PBF meets industry standards.
7.What is the process for return or replacement of LT3965EFE#PBF?
All LT3965EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3965EFE#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#PBF part is unused and in its original packaging.
Return procedure for LT3965EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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