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# BUF16821-Q1: Output accuracy is increased at over temp environment or not?

Part Number: BUF16821-Q1

Hello team,

I am a FAE in charge of Japanese automotive customer.

I got an inquiry about BUF16821-Q1 output accuracy.

In the datasheet, it is written max +/-50mV.

My customer wants to know, if the max data is increased depend on environment (For example, temperature, Vs voltage and so on).

If so, could you please provide worst max voltage of output accuracy at all environment?

Best Regards,

Yuki

• Hello Yuki,

In the electrical characteristics, the output voltage accuracy over temperature is given with +/-25uV/°C

Figure 6 in the datasheet shows the output voltage over temperature.

The output voltage varies with Vs voltage, because the it is directly dependent from Vs. see formula (1) on page 11 in the datasheet.

Best regards,
Brigitte

Best regards,
Brigitte

Hello Brigitte-san,

I understood that output voltage varies with Vs voltage and temperature.

I would like to confirm the condition about output accuracy is max +/-50mV.

Is this condition with code 512 or other code?

When code is '1', how is the output accuracy?

When code is '1023', how is the output accuracy?

Best Regards,

Yuki

• In reply to Yasuo Yuki:

Hello Yuki,

Independent of the code, the output accuracy is not more than +/- 50mV for the parameters given at the top of the electrical characteristics table. We cannot give an absolute value for the output accuracy over the full operating range because the output is always a portion of the supply voltage.

The output accuracy is somewhat dependent on temperature, but according to Figure 6, the influence is below 5mV over the whole temperature range.

Why is this parameter needed with an absolute value? What is connected to the outputs of the gamma buffer in your application?

Best regards,
Brigitte

Best regards,
Brigitte

Hello Yuki,

Best regards,
Brigitte

Best regards,
Brigitte

Hello Brigitte,

The customer has been concerned about the accuracy when the code is low.

could you please check the attached file?

I made the image which you explained before discussion.

My understand is correct?

Best Regards,

• In reply to Yasuo Yuki:

Hello Yuki,

This assumption is not correct. When you have a look into the datasheet, the biggest DNL and INL is at code 512 (see figures 6 and 7). And the +/-50mV is given for all codes, so this is the maximum output voltage inaccuracy at room temperature. Therefore the assumption that the inaccuracy at low code values is biggest is not valid.

Best regards,
Brigitte

Best regards,
Brigitte

Hello Brigitte,

What the customer wants to know is related between output accuracy(+/- 50mV max) and code.

I would like to confirm that you mentioned that output accuracy is fixed all codes.

So, I wrote the image.

I know that DNL and INL also wreak the accuracy.

However, for focusing the +/-50mV max, I wrote.

Anyway, I understand that the output accuracy (+/-50mV max) is fixed all codes.

Thank you and Best Regards,

Yuki