38.8.6 Pad Calibration

The Pad Calibration values must be loaded from the NVM Software Calibration Area into the USB Pad Calibration register by software, before enabling the USB, to achieve the specified accuracy.

Refer to NVM Software Calibration Area Mapping for further details.

Refer to for further details.
Name: PADCAL
Offset: 0x28
Reset: 0x0000
Property: PAC Write-Protection

Bit 15141312111098 
  TRIM[2:0] TRANSN[4:2] 
Access R/WR/WR/WR/WR/WR/W 
Reset 000000 
Bit 76543210 
 TRANSN[1:0] TRANSP[4:0] 
Access R/WR/WR/WR/WR/WR/WR/W 
Reset 0000000 

Bits 14:12 – TRIM[2:0] Trim bits for DP/DM

These bits calibrate the matching of rise/fall of DP/DM.

Bits 10:6 – TRANSN[4:0] Trimmable Output Driver Impedance N

These bits calibrate the NMOS output impedance of DP/DM drivers.

Bits 4:0 – TRANSP[4:0] Trimmable Output Driver Impedance P

These bits calibrate the PMOS output impedance of DP/DM drivers.