Other Parts Discussed in Thread: TUSB522P
Regarding to power supply on SN65LVPE502ARGER, my customer is asking some question.
They use USB protocol analyzer for observe USB signal.
When power supply(Vcc) is unstable, LFPS(U1 exit) for recover from U1 state is not observed on USB protocol analyzer
.( It isn't output from SN65LVPE502A.)
If power supply(Vcc) is changed to LDO for improve quality , above problem is not happened. (LFPS(U1 exit) is sent from USB device LSI.)
They confirmed handshake between HostPC and USB device LSI.
Please refer attached diagram.
(1) When power supply is unstable (like a in this case), what is the impact on Rx/Tx blocks in SN65LVPE502ARGER?
(2) According to datasheet, power supply range is 3.3 V ±10%. (3 to 3.6V : page6)
And the swing of power supply is within power supply range in case of problem .
Why is problem happened at this case? What point do we need to pay attention except power supply range?
(3) According to datasheet,, it seems to support USB 3.0 power management modes (low frequency periodic signals (LFPS) ).
Does it manage U1 state?
If so, how about the possible about the following hypothesis?
The device can’t recover from U1 state and it will transfer to incorrect state then the problem is happened on Rx/Tx blocks.