ADS5403: Noise occurred when enable PRBS function

Rui,

After looking at the data sheet of the ADS5403, there is no mention of PRBS function. The only test pattern options available are what is shown on page 20 under the Test Pattern Output section.

TEST PATTERN OUTPUT
The ADS5403 can be configured to output different test patterns that can be used to verify the digital interface is
connected and working properly. To enable the test pattern mode, the high performance mode 1 has to be
disabled first via SPI register write. Then different test patterns can be selected by configuring registers x3C, x3D
and x3E. All three registers must be configured for the test pattern to work properly.
First set HP1 = 0 (Addr 0x01, D01)
Register Address All 0s All 1s Toggle (0xAAA => 0x555) Toggle (0xFFF => 0x000)
0x3C 0x8000 0xBFFC 0x9554 0xBFFC
0x3D 0x0000 0x3FFC 0x2AA8 0x0000
0x3E 0x0000 0x3FFC 0x1554 0x3FFC
Register Custom Pattern Address
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
x3C 1 0 0 0
x3D 0 0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 0 0
x3E 0 0 0 0

Regards,

Jim

Hi Jim,

Thanks for the reply.

There is the option to turn on the PRBS Pattern at our GUI. 

And why when it's enabled, they saw noise signal?

This GUI is used by multiple EVM's. This is not an option for this EVM. I would look at the register write box on the far right of the GUI after you click on the PRBS test pattern box and see what registers are written. See what changed based on the data sheet register map and this should explain why you are seeing this noise.

Hi Jim,

I have wrote on the original question: When you turn it on, bit 4 is set in register X02.

Thanks,

Rui

I think other settings are changed as address 0x2 bit 4 is an over  range setting. This should have no effect on the output data. Do not use this setting in the GUI as it is not valid with this device. 

Hello Jim,

I understand that this GUI could also be used for ADS5400 which has the option to turn on PRBS Pattern. However, when my customer turn it on, still the x02 will change from 0790 to 0780. See below: 

I believe there must be a reason why it changed and somehow it caused noise.

Would you please take a look?

Thanks,

Rui

Muffin,

In register 0x02, bits 0-4 and 11-15 must always be written as "0" per the data sheet. Writing a "1" to any of this bits could cause the part to not work properly. The PRBS option button should not be on this GUI as none of the parts used by this GUI has this feature.

Regards,

Jim 

Hi Jim,

Thanks, I understand this should not be no the GUI.

But the fact is also it's on the GUI and when my customer turn it on he sees noise. He would like to know why. 

This should not have effect on the output signal but indeed it has.

Thanks

Rui

Muffin,

In register 0x02, bits 0-4 and 11-15 must always be written as "0" per the data sheet. Writing a "1" to any of this bits could cause the part to not work properly. The PRBS option button should not be on this GUI as none of the parts used by this GUI has this feature.

Regard

I have nothing else I can add. Sorry.