Features and Benefits
- Eight Independent 15V/110mΩ NMOS Switches
- Controls LED Dimming of Strings Up to 54V
- I2C Serial Interface with Programmable Address
- I2C Packet Error Checking with CRC-8
- Programmable 256:1 (8-Bit) PWM Dimming
- 11-Bit Precision Exponential Fade with Programmable Time
- Independent On/Off Control for Each Switch
- Programmable Shorted/Open LED Threshold with Fault Reporting
- Internal PWM Signal Generator
- Programmable Watchdog Timer
- Accurate VIN Referred Enable Pin
- User Defined Power-Up/Reset State of Switches
- Thermally Enhanced TSSOP Package
The LT3967 is an LED bypass switching device for dimming individual LEDs in a string using a common current source. It features eight individually controlled floating source 15V/110mΩ NMOS switches. The eight switches can be connected in parallel and/or in series to bypass current around LEDs in a string. The LT3967 uses the I2C serial interface to communicate with a microcontroller. Each of the eight channels can be independently programmed to bypass the LED string in constant on or off, or PWM dimming with or without fade transition. Using the programmable fade option provides 11-bit resolution exponential transition between PWM dimming states. The LT3967 provides an internal clock generator and also supports an external clock source for PWM dimming. The LT3967 reports fault conditions for each channel such as open LED and shorted LED. The four address pins allow 16 LT3967 devices to share the I2C bus and define the power-up state of the switches.
- Automotive LED Headlight Clusters
- Large LED Displays
- RGBW Color Mixing Lighting
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demonstration circuit 2686A is a 1.3A 8-switch matrix LED dimmer system with an I2C to CAN-physical transceiver featuring the LT3967 and LT3960. This demonstration circuit connects directly to a LED string and LED driver demonstration circuit to allow for independent dimming control of up to 8 channels of LEDs. A Linduino® One demonstration circuit is used to interface with the board and can connect in one of two different ways:
- Connect directly to a Linduino One demonstration circuit with a QuikEval™ ribbon cable.
- Connect using the LT3960 break-off board to connect to the I2C master device, but pass data over two twisted pair lines to the LT3960 on the main PCB.
The LT3967 matrix dimmer features 8 individually con-trolled 1.3A rated floating NMOS switch channels and can support up to 56V of LEDs per device. The channels of the LT3967 can be configured for series connections, or non-series connections. Additional DC2686A demo circuits can be connected in series for higher number of LEDs, or in parallel to allow for higher current operation. Resistors are used to configure both the I2C slave address as well as the default start-up state. The default configuration for DC2686A sets the I2C address as 0000 with all LEDs off. See the LT3967 data sheet for details.
The LT3960 I2C to CAN-Physical transceiver is used to send and receive I2C data through harsh or noisy environments at up to 400kb/s using the CAN-Physical layer for differential signaling over twisted pair connections. Both SDA and SCL data lines are converted to differential signals and are shared between devices connected to the bus. This allows for physical separation of the I2C source with the LT3960 transceiver board and the LT3967 main PCB along with the LED driver.
This demo circuit is designed to be easily configured and interfaced with a compatible low output capacitance LED driver and LED string. It can easily be directly attached to a buck LED driver or a floating buck-mode LED driver. More sophisticated setups with series matrix dimmers for higher number of LEDs such as 12 or 16 is possible. Please consult factory applications for details or look for more details on analog.com.
The LT3967 and LT3960 data sheets give complete description of the parts, their operation and applications information. The data sheets must be read in conjunction with the demo manual for demonstration circuit DC2686A. The LT3967EFE is assembled in a thermally enhanced 28-lead TSSOP package. The LT3960EMSE is assembled in a 10-lead MSOP package.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
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