In customer's PCBA, the POR_B signal is driven with a RC reset circuit. While in RT1060 EVK, the POR_B is controled with a reset supervisor IC(UM803RS @2.63V). Below is the waveform of power sequence on customer's board. Are there any potential issues that customer should careful?
I hope you are doing great.
The best is to use an reset supervisor IC. See the below excerpt from AN13202
EMC Design Recommendation on i.MXRT Series
The potencial issues that I can see, with only having the RC circuit, is that you loose the power supply low voltage detection and precise reset de-assert timing. Also, with the RC circuit, the system may be out of spec, POR_B is not actually asserted until the last supply rail reached its working voltage
The RC circuit may improve EMC performance, but it is not the recommended solution for POR_B.
Additionally, In our EVK, the reset assert and de-assert looks like this when the during a Power on reset and SNVS wake up events. The reset is asserted with a considerable marging, more than 200 ms after the last rail booted.
All the best,
Diego
I hope you are doing great.
The best is to use an reset supervisor IC. See the below excerpt from AN13202
EMC Design Recommendation on i.MXRT Series
The potencial issues that I can see, with only having the RC circuit, is that you loose the power supply low voltage detection and precise reset de-assert timing. Also, with the RC circuit, the system may be out of spec, POR_B is not actually asserted until the last supply rail reached its working voltage
The RC circuit may improve EMC performance, but it is not the recommended solution for POR_B.
Additionally, In our EVK, the reset assert and de-assert looks like this when the during a Power on reset and SNVS wake up events. The reset is asserted with a considerable marging, more than 200 ms after the last rail booted.
All the best,
Diego
