I am trying to figure out what is causing an Allegro A2982 source driver to burn up.

The source driver (A2982) is connected to the coil of a Panasonic TXS2-9V relay. The source driver and coil are connected by about 3 feet of wire. The source driver is on the high side and the coil is on the low side.

The rail of the source driver (Vs) is 9 V. The source driver output is ~7.4 V. The peak voltage of the spike, measured across the inductor, is ~13.2 V. Note: I am using a differential probe to measure the voltage across the coil.

Is it a valid concern that:

1. This voltage spike is causing damage to the source driver?
2. The 9V supply may see the voltage spike and cause damage?
3. The Vbe reverse breakdown voltage of the darlington-pair may be exceeded and cause damage?

If the spike is causing damage, is there a way to reduce or mitigate the spike?

Circuit Schematic

The circuit is used to turn off a motor. Below is a scope capture. The squared area in red is when the motor turns off. The output of the relay controls an ON/OFF signal (3.3V or GND). Note: The relay coils are located near the motor. Three outputs of the source driver are used to drive three separate relay coils.

Closeup

posted about 1 year ago

CC BY-SA 4.0

1y ago

mrbean‭

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