How to use LPC4370FET100 HSADC in true differential mode?

[brandongallian]

Hello,

I'm trying to set up the 12-bit ADC on the LPC4730FET100 (using LPC-Link2 as a demo board) to operate in true differential mode. I want to use ADCHS_0 (pin A2) as the positive end analog input, and ADCHS_NEG (pin A3) as negative end analog input. The only information I can find in the user manual says:  "It is possible to deselect the internal vin_neg and supply vin_neg externally at pin ADCHS_NEG by setting DCINNEG to 0. When only one input is used then the ADC can be used in true differential mode."  However, after setting DCINNEG = 0, ADCHS_NEG (pin A3) still outputs 0.5 volts. Is there something else I need to do to configure ADCHS_NEG as an input?

Thank you

[Hui_Ma]

Hi,

The LPC4370 datasheet page143 with below description:

When DCINNEG is set to 1:

When DCINNEG is set to 0, provided voltage at ADCHS_NEG pin (ADCHS be used in true differential mode):

Wish it helps.

Have a great day,
Mike

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