DRV103: DRV103 latchup?

Hi David,

Welcome to E2E!

Would you be able to share a schematic to see the application of the DRV103?

Best regards,

Andy Robles

Hi Andy;

Find attached schematic for the board in question. The driver I'm having problems with is U10 in the lower right corner. I've verified the TTL input to be stable at 0V during powerup. Thanks for the help.

/DMR

PCB ASSY CDS-1510 CONTROLLER (82-612B).pdf

Hi David,

The behavior the DRV103 is exhibiting is definitely unusual. With the input being driven low the output of the DRV103 should be off and shouldn't be latching the solenoid on.

I checked the schematic of the DRV103 and didn't find anything wrong with the configuration. Furthermore, the device is configured the same way as the other DRV103's for which it should work as intended.

Have you tried doing a AB Swap to ensure that the suspected device is causing the failure?(i.e. swap the suspected unit with a known good unit to retest the board).

Best regards,

Andy Robles

Thanks Andy;

I don't have another of this board populated but I did replace the suspected device on the one I have. No difference. I'm going to try isolating the 22V10 and starting the board w/ just a 10K pulldown on the DRV input. If it still does it under that condition I'm wondering whether a defect/bad solder etc on one of the passive components/connections on pins 1,2,3 could cause the problem.

Best Regards;

Dave Robertson 

Hi David,

I have not heard of an issue like this before with the DRV103 for which we do not have history of PINS 1, 2, or 3 causing such effect on the DRV103. Have were you able to isolate the 22V10 and pulling down the input to the DRV103 input? Would you be able to share your results?

I haven't seen this problem before and would like to confirm if it is a device or board issue.

Best regards,

Andy Robles

Hi Andy;

I lifted the TTL input pin to the DRV103 and put a 10K pulldown on it (no PLD control) and it still latched the relay on. I suspect it's ground path related as the relay works as-programmed but only if I have the 24V and 5V grounds (normally isolated) tied together on the board AND the device I'm powering off the 7.5V rail (also referenced to the 5VGND) unplugged. Still at a loss to explain how it's able to keep the relay energized absent a valid HIGH at the TTL input or why it's only that particular relay.  

Best;

Dave R

Hi David,

Since the configuration on the DRV103 is the same as the other DRV103 on your board, and they all have normal configurations that can be found on the datasheet I don'/t believe this to be a problem with the DRV103 itself, but with the board. In the layout are all DRV103's routed the same way? Have you tried changing the relay to make sure it's a not a problem with the relay?

Best regards,

Andy Robles

Hi andy;

Finally got back to this this week and found out the relay only has a problem when my control board peripherals are chassis referenced. Turns out that the wire to the relay in question was pinched under a washer and making contact with the chassis. And as soon as I plugged in a peripheral that tied the 24V GND to chassis the relay had its low-side path - same as if the driver were turned on. Fixed now.  Thanks for all your help.

/DMR