Fully Differential ADC Mode LPC4370

QM — Fri, 03 Dec 2021 05:13:08 GMT

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

Re: Fully Differential ADC Mode LPC4370

xiangjun_rong — Mon, 06 Dec 2021 10:13:34 GMT

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

XiangJun Rong

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Fully Differential ADC Mode LPC4370

Re: Fully Differential ADC Mode LPC4370