Part Number:TMS320F28075
Hi, Champs,
My customer is using F28075 and here is a reset issue.
When Vddio drops from 3.3v to 2.7v, the device get reset and the XRS pin was driven to low for 45us, but after that it turned back to high for 189us, and then reset again. The external RC circuit follows DS like below (R=4.7k, C=1nF).
I learnt from the forum (not explicitly indicated in either DS or TRM) that Soprano has no BOR circuit, so some questions are:
1. Why this occurs?
2. Is it power-down reset or watchdog reset?
a. If it's the former, what's the trip point for reset?
b. If it's the latter, does that mean invalid Vddio caused the device out of work, but the clock is still there to trigger WD?
However, the timing seems not match as customer used an external 16MHz oscillator. should OSCCLK equals to INTOSC2 or external X1/X2? (512/16MHz=32us and 512/10MHz=51.2us)
In the other hand, even it's WD reset with 512/10MHz=51.2us, how can we explain the latter 189us high level and then low?
The external RC circuit and waveforms are as following (blue: voltage on point B, pink: voltage on point A):
Best Regards,
Ricky Zhang