topic Re: ADCHS LPC4370 Problems creation interface. in LPC Microcontrollers

ADCHS LPC4370 Problems creation interface.

fabiodebernardi — Fri, 17 Feb 2017 07:51:44 GMT

good morning,
We are undertaking a project with the micro lpc4370 and we find it difficult to properly size the interface circuit for the analog readings by adchs.

We use the internal vref to 0.5V, in the datasheet is reported that the range of values are compared -+400mV to vref. But in the datasheet lpc3470 page. 131

Symbol Parameter Conditions Min Typ Max Unit

VDC DC input common mode level 0.1 0.5 0.9 V
-2048 0 +2047 digit

We (range) input voltage peak-to-peak 0.72 0.8 0.88 V

The minimum value in this case may range from 0.1 to 0.14V?

The maximum value in this case can range from 0.86 to 0.94V?

We can not correctly interpret these data.

Can you help?

Thanks and good job

Re: ADCHS LPC4370 Problems creation interface.

okcn — Fri, 17 Feb 2017 15:36:40 GMT

you mean : it should be 0.1 0.5 0.9 V

but now it is 0.1~0.14 0.86~0.94

and the signal you send is 0.72 0.8 0.88

What is the freq of your signal? I guess, Maybe 4370 's ADC only can measure high freq signal.

And maybe you should measure your signal with Link-2- Labtool first, and compare that with your data.

Re: ADCHS LPC4370 Problems creation interface.

Hui_Ma — Tue, 21 Feb 2017 07:23:10 GMT

Please check my comments with your submit another thread(with same question):

https://community.nxp.com/thread/445056

Wish it helps.

Have a great day,
Ma Hui
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Re: ADCHS LPC4370 Problems creation interface.

haksookim1 — Thu, 07 Apr 2022 08:42:19 GMT

I'm using ADCHS from LPC4370.
I have a question because the ADC port is damaged during long-term use.

Circuit/Situation Description
1. Used as Vin neg pin output.
2. I checked the data sheet. ( 3.3V Max)
3. Noise is generated in ADCHS(1~3) as mux operation waveform

In the datasheet, the ADC input voltage limit is set to 3.3V and is being used.
The circuit I am using is
ADCHS0 ( max Input voltage 3.3V)
ADCHS1 ( max Input voltage 1.2V)
ADCHS2 ( max Input voltage 1.2V)
ADCHS3 ( max Input voltage 1.2V)
and the problem seems to occur when ADCHS1~3 periodically generate noise and ADCHS0 inputs at 3.3V level.

I am asking a question based on the above.
1. What is the maximum input voltage when using ADCHS (12bit ADC)?
2. If there is no problem with the input voltage, how can the phenomenon that the Mux operation waveform interferes be eliminated?