LIN chip handles multiple RGB LEDs for dynamic lighting applications

June 30, 2015 // By Christoph Hammerschmidt
The E521.31 from Elmos AG provides an easy and variable RGB LED system design with LIN bus interface. The component can drive six or more RGB LEDs in multiplex mode, making it the device of choice for light systems to display status information, such as the battery charge state on electric vehicles.

The component is equipped with a 16-bit microcontroller, voltage regulator and a LIN transceiver with BSM (bus shunt method) auto addressing. The device can store program and parameter data in 32 to 54 kByte of flash memory and 1kByte of RAM. It features an integrated voltage regulator with an output rating of 5V / 100mA. LED drivers with a switching power of 50mA each are integrated to control the LEDs. In addition, the E521.31 is also equipped with multiple ADC inputs, for example to measure current or voltage values from the internal or external temperature sensors. For fast flashing via the LIN interface, a flash mode (115 kBd) is available.

The BSM technique is a robust method for addressing nodes within a LIN bus system and has proven itself in practice millions of times over. It has established itself among several OEMs in applications such as air conditioning control system damper drives, and has been proven to be robust and reliable in over 10 years of operation across multiple platforms. All required development and diagnostics tools for this method are already in use in the field.

The method used in the IC at hand exhibits very good fault tolerance such as "Loss of Ground" and can be used in "mixed" installations with standard LIN bus devices. This allows for system integration of bus devices which don't support the BSM method. Every bus device can be reached via the protocol at any time, even during addressing of the bus members. Broadcasts can be sent to all members at any time. Thanks to a simple software solution implemented in the slave, the master can perform an addressing plausibility check at any time. Thanks to this unique function, a diagnostics check can even be performed on the address assignments.

The component is available in the QFN32L5 package. The E521.31 meets the LIN 2.1 standards.

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