Current limit not being enforced in PPS mode about pd_micro

[ryan-ma]

Hi Nik,

The current limit in PPS is quite coarse. The PD spec only requires the PD power supplies to provide accuracy of 150mA when souring more than 1A, or +/-5% when souring more than 3A.

USB_PD_R3_0 V2.0 20190829.pdf - page 246 - 7.1.4.4 Programmable Power Supply Current Limit

......
The PPS Operating Current regulation accuracy during Current Limit is
defined as iPpsCLNew. The minimum programmable Current Limit level is iPpsCLMin.
......

USB_PD_R3_0 V2.0 20190829.pdf - page 309 - 7.4.1 Source Electrical Parameters

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iPpsCLMin (Minimum Current Limit setting)
- Minimum: 1A
iPpsCLNew (Current Limit accuracy)
- 1A ≤ Operating Current ≤ 3A : +/-150mA
- Operating current > 3A : +/- 5%
......