AnsweredAssumed Answered

LPC54018 ADC accuracy

Question asked by Hanson He Employee on Feb 24, 2019
Latest reply on Mar 19, 2019 by xiangjun.rong

Hello,

 

We test SDK_2.5.0_LPCXpresso54018\boards\lpcxpresso54018\driver_examples\adc\lpc_adc_basic\iar example for 

LPCXpresso540xx Eval Brd Rev E. We get below result:

 

3.253v for Power on LPC54608 VDD pin VDD_TARGET_IC.

When input 0.156v actual value voltage, get adcResultInfoStruct.result 192 on channel 4, theoretical value is 0.152v=(3.253/4096 X 192), error is 0.004v =(0.156v-0.152v). 

When input 1.650v actual value voltage, get adcResultInfoStruct.result 2048 on channel 4, theoretical value is 1.6265v. 

error is 0.0235v.

When input 1.488v actual value voltage, get adcResultInfoStruct.result 1856 on channel 4, theoretical value is 1.474v.

Error is 0.014v. 

When input 3.253v actual value voltage, get adcResultInfoStruct.result 4093 on channel 4, theoretical value is 3.2506v. 

Error is 0.0024v.

 

We want to know why error could up to three digits after the decimal point when close to 0v or close to Vdd voltage,

but only two digits after the decimal point from 1v to 2v voltage. 

Do you have some improve method for this?

Outcomes