LPC55S0x / LPC550x Datasheet v1.4 Table 39 Footnote [7] "For best performance" clarification

[ahlee16]

Link to datasheet: https://www.nxp.com/docs/en/data-sheet/LPC55S0x_LPC550x_DS.pdf

In LPC55S0x / LPC550x Datasheet v1.4, Section 12.2 16-bit ADC characteristics, Table 39, Footnote [7] is updated (compared to Datasheet v1.2):

My question:

1. Where should Footnote [7] be applied? In Section 12.2 and Table 39, there is no reference to Footnote [7].

2. What does the sentence "For best performance" mean? Is it ADC accuracy, ADC conversion time or other meaning?

3. If we should force ADC offset calibration to -16, does it conflict with LPC55S0x/LPC550x User Manual UM11424, Section 39.7.5.3 Calibration?

Thanks.

#LPC5506

[ahlee16]

Hi @ZhangJennie , thanks for your response.

Clarification: To improve ADC accuracy and ADC conversion time, we should force the offset calibration to -16, prior to performing the gain calibration.

Is my understanding correct?

[ZhangJennie]

Yes,correct.

[ZhangJennie]

Hi 

The ADC offset calibration does not result in an accurate result.

Workaround: For best performance force the offset calibration force to -16. Set this prior to performing the gain calibration.

it would affect ADC accuracy and ADC conversion time.

Thanks,

Jun Zhang

[ahlee16]

Hi @ZhangJennie ,

To force the offset calibration to -16:

* set register OFSTRIM bit[4:0] to10000b and bit[20:16] to 10000b

Am I correct?

Reference: