class C (+1.8V) capabilities

Hi, I found out why class C (+1.8V) capable UICC are still used as class B (+3.3V). This is because the board provides +3.0V on VCC_PHONE, forcing the phone to use class B. this voltage is coming from VCC_SIM. Normally VCC_SIM should only get the power from VCC_PHONE (in sniffing mode), through the power switch FPF2005, or from the LDO AP3332 (in card reader). Currently both are enabled (bug). This should be prevented in software as there is no hardware mechanism to prevent that (fail). Some power from the LDO is going backwards though the power switch, providing +3.0V on VCC_PHONE (another hardware fail). Also, SIMtrace will not be able to decode +1.8V traffic because Vih (voltage input high level) is at +2.3V. One solution would be to power VDDIO at 1.8V, but this is a bad solution as the USB will not work anymore. For the v2 board I intend to have the following: - 1 translator/level shifter for SIM<->CPU, with selectable 1.8/3.3 - 1 translator/level shifter for PHONE<->CPU, with selectable auto/1.8/3.3 - VCC_SIM can be set to VCC_PHONE,1.8V,3.3V - power forward with diode behaviour any correction, comments or recommendation are welcome, kevin