Showing results for 
Search instead for 
Did you mean: 

Why would STSPIN220 drive power to the outputs at initial power-on?


 To ask this question another way, what is expected at the output pins when Vs < 1.5V during power-up?

I have a design for driving a linear actuator which uses the STSPIN220. My customer has an issue related to unexpected device power off, and those events correspond to power-on of the STSPIN220.

During their investigation, they found significant voltage on the output pins immediately when the device is powered on (via a high-side FET to switch the voltage). While I can't confirm the behavior myself since I don't have hardware, I am told that there can be a voltage spike of >1V which occurs at the motor driver outputs, regardless of how STBY and EN are set. Part of the current working theory is that the driver is pulling signifcant current at this time, possibly due to both sides of the H-Bridge being enabled, and that is causing the regulator to drop-out.

As far as the STSPIN220, it's been speculated that there is a point at which the outputs are powered before the threshold voltage needed for driver power-on is reached, but this seems contrary to section 6.1 of the datasheet which states "At power-up, power-down and when leaving the standby condition, the EN/FAULT pin is forced low until the

internal circuitry stabilize."

Given this, what is the behavior of the output pins before the driver reaches ~1.5V required to power the driver? Does the state of STBY or EN affect this behavior? Is it expected that any voltage should be present on the output pins during device power-up, especially prior to STBY and EN being enabled?

Thanks in advance. I will be working on getting additional details, but wanted to reach out in case there was something in the driver documentation I missed.