STM706 WDI Reset Pulse

[d.kearney]

Hello, 

The STM706 is setup with the WDI pin pulled low via 10K resistor, all other pins are in a normal state (VCC high). When the WDI pin is probed in this condition a 200ms, 500mV pulse can be seen every 1.7 seconds. Is this the pulse referenced in the datasheet section 3.3 and is it expected performance?

Thanks,

Diarmuid

[Peter BENSCH]

Welcome ​@d.kearney, to the community!

I currently do not have a board with the STM706 available, so I cannot verify the behaviour. Anyway, the WDI pin seems to be a pure input, so with a connected pull-down there should be nothing to measure. However, the WDI pin has the additional function of disabling the watchdog when WDI is floating, and the observed pulse is probably part of the internal test for a floating pin. Since the pulse height is clearly below the VIH limit, there is also no risk of triggering here.

Since the development of this device dates back to the last century, it is now a bt difficult to still be able to ask a developer about it.

Hope that helps?

Regards
/Peter

[d.kearney]

Hi Peter, 

Thank you for the valuable feedback. The STM706 is identified as an alternative for a similar Max linear Part that is going EOL, hence the origin of the request. The dual functionality of the WDI pin could well be the source of the signal in question. I will perform further testing to ensure it meets the required functionality as per the datasheet. 

Regards,

Diarmuid

[d.kearney]

Hi ​@Peter BENSCH , 

Back again with a quick question regarding the ESD ratings for the device. The datasheet does not state any ESD rating (HBM or CDM). Would you be able to say what level of protection the device has?

Thanks,

Diarmuid

[Peter BENSCH]

The STM706 developed around the turn of the millennium has no ESD protection at all, so this must be added externally if needed, for example with an ESD protection diode from our extensive portfolio.

Hope that helps?

Good luck!
/Peter