DOUT voltages values in ON and OFF cases

Telematics
1

Hi.

We need to acheive immobilzation in electric vehicles having 72VDC wires using the same 12/24V 5-pin relay that is usually installed with trackers (say FMB930). The part where we are stuck is relay coil energizing. If we attach one side of coil with 12V (converting 72V to 12V using buck converter) and another with DOUT, what voltage will DOUT output when immbolizer is ON and when OFF? The power wires of tracker is connected with 72V.

2

The DOUT on an FMB930 is an Open Drain (sinking) output, meaning it acts as a switch to ground (0V) when the immobilizer is active and remains floating (high impedance) when inactive. When the relay is ON, the DOUT pin will be approximately 0V, pulling current from your 12V source through the coil; when OFF, the pin will float and show the potential of your 12V rail (around 12V) if measured through the relay coil.

  • Immobilizer ON (DOUT Active): Output is 0V (Ground), energizing the relay coil.

  • Immobilizer OFF (DOUT Inactive): Output is Floating, the circuit is open, and the relay stays off.

3

Thanks for the information. Is this valid only for FMB930 or all tracker models?

4

hello @Awais

in order to operate well, the device and the relay should have the same power source,

When the Dout is high >> the device will provide the GNS to the coil allowing to complete the circuit and activate the relay

When Dout is low >> the device will open the circuit >> the relay will be off

  • Immobilizer ON (DOUT Active): Output is 0V (Ground), energizing the relay coil.

  • Immobilizer OFF (DOUT Inactive): Output is Floating, the circuit is open, and the relay stays off.

@j873ohnwarren Good explanation, thanks

6

This topic was automatically closed after 45 days. New replies are no longer allowed.