P3041 SERDES voltage change

[cmc_dave]

I am working with the P3041 We are using PCIe Gen 1 x 4 lanes. I would like to increase the amplitude of the transmitters, I did change the SERDES supply voltage (XVDD) from 1.5 to 1.8V and connected a 1.8V supply. I also strapped CPU_LAD[26] to GND. I did not see and increase in the amplitude, is there something to change in the RCW to force the transmitter to use the higher voltage?

Thanks

[ufedor]

Please refer to the P3041 QorIQ Integrated Processor Hardware Specifications, 2.19.4.3.1 PCI Express DC Physical Layer Transmitter Specifications.

As you can see, the DC parameters are the same no matter XVDD=1.5V or 1.8V. Actually 1.5V and 1.8V are both functional value that can be selected for the XVDD voltage. The reason for having two voltages is mainly to provide option to customer to select the same voltage as the DDR power source, this will reduce the number of DC-DC converters circuitry on customer board. When customer board is running DDR3, they can use the same 1.5V source as XVDD power source according to hardware spec. If they use DDR3L (1.35V), then they have to provide independent 1.5V or 1.8V power rails for XVDD.

The PCIe TX amplitude is not adjustable.

[cmc_dave]

Thanks for the input!