Intelligent SSR for Advanced Automotive Applications

SGS-THOMSON Microelectronics, the world leader in smartpower technology, has introduced an intelligent solid state relay optimised for automotive and other radio applications. Built with the well proven second generation VIPower M0 technology, the VN370B integrates control and protection circuitry along with three power DMOS transistors configured as independent high side drivers. Key features include active current limitation, fast demagnetization of inductive loads and reduced radio frequency emission.

The VN370B provides one high current channel (1A nominal current) and two identical low current channels (0.3A). Each channels is independently controlled by a TTL-compatible input signal and drives a resistive or inductive grounded load. The active current limiting circuitry limits inrush or short-circuit current to 4.4A for channel 1 or 0.72A for channels 2 and 3. In the event of a sustained anomalous condition, the temperature protection circuitry shuts down all channels (channel 1 fault) or the offending channel only (channel 2/3 fault) until the chip cools down to the appropriate temperature.

Protection is also provided against overvoltage (27V, typical) and loss of the ground connection, a condition which causes all three channels to be shut down. The VN370B operates over a wide 7-24V supply range, ensuring reliable operation with all automotive battery conditions. In addition,when any channel switches off an unclamped inductive load, the corresponding output voltage is clamped to typically -20V.

Today's automobiles often contain frequency sensitive equipment such as high performance radios and mobile telephones. The VN370B therefore features a special charge pump configuration that reduces radio frequency emissions. Along with simpler driving, space saving and the improved reliability of a monolithic solution, these features make the VN370 ideal for automotive CD and tape player, antenna relays and display driving applications.

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