ADS8688: ADS8688 related issues

jeno.zhang

Part Number: ADS8688

Hi，

The ADS8688 manual shows that the maximum conversion time is 850ns, but the actual test is 2us. Please help analyze the reason.

Thanks!

over 1 year ago

0 Tom Hendrick over 1 year ago

TI__Guru**** 180751 points

You need to apply a 17MHz clock with the minimum tsu_CSCK in order to achieve full speed operation of the ADS8688. You are waiting almost a micro second to start the clock, which is causing the largest delay.

0 jeno.zhang over 1 year ago in reply to Tom Hendrick

Expert 2855 points

Hello Tom，

According to a 17M clock, the 15 clock cycles are already 880ns This is the fastest speed, and if the clock frequency is lower, the time will be longer, so it is difficult to meet this indicator in practical applications. Is there a problem with the setting here? Why is the conversion time so long? Please help analyze and how to set it.

Thanks！

0 Tom Hendrick over 1 year ago in reply to jeno.zhang

TI__Guru**** 180751 points

Throughput is based on the conversion and acquisition time, which are 850nS and 1150nS respective. The two add up to 2000nS or 500kSPS.

0 jeno.zhang over 1 year ago in reply to Tom Hendrick

Expert 2855 points

hi，

Why is the maximum conversion time 850ns, not the minimum? For example, if I reduce the frequency, the time should be greater than 850ns.

Thanks!

0 Tom Hendrick over 1 year ago in reply to jeno.zhang

TI__Guru**** 180751 points

Perhaps I don't understand your question here. Datasheets are usually written with the highest throughput of the device in mind. At full speed with a 17MHz clock, the conversion takes 850nS. If you slow down the clock, you slow down the throughput.

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ADS8688: ADS8688 related issues