MPC8313 hreset

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MPC8313 hreset

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Contributor I

Hi,

I have a question regarding the MPC8313C hreset signal. Currently on my design, the hreset signal is driving many devices (10) and the trace on the PCB is very long. I'm wondering if I should use a buffer to drive the devices that are far from the hreset source.

Regards

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NXP TechSupport
NXP TechSupport

Please measure output voltage, when the device is driving HRESET low. If this voltage is higher than limit specified for logic "0" input voltage for all connected loads, than you need to put a buffer.

Trace length effects may be in signal "ringing" caused by reflections from the unterminated far end. If you do not see this effect or your connected devices are not sensitive to this ringing (to multiple reset assertions instead of one), than long trace may be ignored. If you wish to eliminate this effect, than impedance matching should be done - output buffer impedance should match trace impedance. This can be done by placing series resistor at near end (at signal source) or parallel termination at far (remote) end.


Have a great day,
Alexander

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