LM98714: 1LSB and DNL calculation

Kazuto Tatsumi

Intellectual 2820 points

Part Number: LM98714

Hi team,

Could you help me to answer the question from customer listed below?

1LSB at 2.4V mode = 2.4/65535, is this calculation correct? Otherwise the datasheet shows 2.3V as input voltage as following, so that do we need to use 2.3V for this calculation?
Is the DNL as -0.95/3.25 in 16bit? If so, I think the DNL in 12bit is better because of the calculation below. Is my understanding correct?
1LSB in 16bit = 2.4V/65535 = 36.62165uV
3.25LSB = 36.62165*3.25=119.0204uV
1LSB in 12bit = 2.4V/4095=586.0806uV
Therefore, the DNL becomes better because DNL(16bit) < 1LSB(12bit).

Regards,
Kazuto

over 3 years ago

0 Norikazu Takebayashi over 3 years ago

TI__Intellectual 1820 points

ADC range is 1.18V, (refer to data sheet page 8). Theoretically better DNL (in LSB) is expected if using MSB 12bit.

best regards,

Norikazu

0 Kazuto Tatsumi over 3 years ago in reply to Norikazu Takebayashi

TI__Intellectual 2820 points

Hi Takebayashi-san,

I understood the input voltage can be up to 2.4V at 2.4V mode but it's reduced after PGA, so that 1LSB at 2.4V mode is 1LSB = 2.4/65535, from input side. is my understanding correct?

If so, which voltage should be used to calculate LSB, 2.3V or 2.4V?

Regards,
Kazuto

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LM98714: 1LSB and DNL calculation