Fully Differential ADC Mode LPC4370

[QM]

Hi NXP, 

I have some questions about using the LPC4370 (Link2 dev board) ADC in fully differential mode. I am wanting to drive the ADC from a fully differential output (ADRF6510 amplifier), but the minimum common mode voltage I can achieve with the amplifier is 1.5V. 

Is it true that I need to supply one of the outputs of the amplifier to the ADCHS_NEG pin? And is it also true that this ADCHS_NEG voltage needs to remain within around 0-1V? 

On the data sheets it often assumes that you are not supplying anything to this ADCHC_NEG pin and use the nominal 0.5V, which makes sense that you have to swing around that 0.5V ± 0.4V. But it is not clear to me what happens if you use a higher voltage such as 1.5V. 

It probably won't work, but just want to make sure before implementing a more complicated solution. 

Regards, 

Quinn

[xiangjun_rong]

Hi,

As the following fig in data sheet of LPC4370, the ADCHS_NEG is 350 mV<Vin_neg<900 mV.

If the common mode voltage of ADRF6510 differential output is 1.5V at least, I suppose you can not connect the ADRF6510 differential output to ADCHS_NEG directly.

I suppose you can use AMP to establish a differential to single-ended converter and connect to analog pin of LPC4370

Hope it can help you

BR

XiangJun Rong