Automotive grade relay driver IC

20th April 2007

ES Admin

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The new A2550 from Allegro MicroSystems Europe is an automotive grade relay driver IC which incorporates a 5 V voltage regulator, watchdog and reset circuitry, and three low-side DMOS relay driver outputs, providing robust performance over extended voltage and temperature ranges. The new device is designed to provide key functions in automotive relay-based applications where a microprocessor is used to implement complex system control and requires a logic supply voltage, power-on reset circuitry and watchdog capabilities. These systems - typically used for the control of wipers, seats, sunroofs and other closure systems - often have an architecture consisting of brush motors controlled very simply by relays driven with simple on/off commands from the control system.

The three low-side DMOS drivers in the A2550 can drive relay coils of up to 250 mA each. Each driver integrates rugged voltage clamps that eliminate the need for external free-wheeling diodes and enable the drivers to survive automotive load dump pulses of up to 48 V to ensure adequate survival in
harsh automotive environments.

The 5 V linear regulator provides 40 mA of output current with a tolerance of 2% over the operating temperature range. To enhance the device's usefulness in automotive applications, the regulator output and the low-side driver outputs are protected against over-current conditions.

The integral power-on reset circuitry and the built-in watchdog circuit combine to service the monitoring and reset requirements of a system
microprocessor. The user can adjust the reset timing and the watchdog
timeout by changing the values of two external capacitors.

The A2550 is supplied in a 16-lead TSSOP package with exposed pad.