Damage stepper motor IC by connecting V(motor) without V(logic)?

[eem2am]

Hello,

We are using the NJM2673 stepper motor driver to drive stepper motors from a 36V rail.
The NJM2673 , as well as having internal H-Bridges, it has a 5V logic supply.

NJM2673 DATASHEET:

**broken link removed**

Sometimes the stepper motors are not used and yet still the NJM2673 is connected to the 36V rail.
-during these times when the stepper motors are idle, we switch off the 5V rail supply to the NJM2673 stepper driver IC’s..
(-this is so that the NJM2673 does not keep drawing current from the 5V rail when the stepper motors are not required to be used).

-my question is, ….
- do we risk damaging the NJM26763 by having the 36V rail connected to it when its 5V input pin has 0V on it?

 

[alexan_e]

First of all i see that the 5 volts supply only the control part of the chip and the current consumption is a few ma, so disconnecting the 5v saves you 60mA max (38mA for 5v supply according to the datasheet) and i don't see the need to save such a low current
The output transistors need a positive voltage in the base to turn on so i assume they can't be turned on when there s no digital supply but still keeping the output stage voltage on while you remove the control circuit voltage is not a recommended action in my view.
If you are going to remove something this should be the high motor voltage.

Alex

 

[dick_freebird]

You would not want to assume anything about the guts.
Why not contact the manufacturer's application support
if you can't find the information in the product docs?

However the datasheet says you can apply the supplies
in any sequence which implies that VCC can be 0 for some
(perhaps infinite) duration.

I would be less confident about letting VCC be open, though.