About conversion time of ADS1120

Masami Michino

Other Parts Discussed in Thread: ADS1120

Dear, All

A customer is considering ADS1120.
But it isn't possible to secure 4.096MHz clock and 4MHz clock is being considered.
The use mode considers "Turbo Mode".
When using 4MHz for Tclk, I'd like to know influence to "Table 7 Conversion Times".
When setting "Norminal Data Rate" as 2000SPS equivalence, how does the following value change?
* Norminal Data Rate
*-3dB Bandwidth
* Actual Conversion Time (Continuos Conversion Mode)
* Actual Conversion Time (Single-Sgot Mode)

Thanks, Masami M.

over 10 years ago

0 Bob Benjamin over 10 years ago

TI__Guru** 113765 points

Hi Masami,

The ADS1120 does not require an external clock. If you connect the CLK pin to DGND, the internal clock will be used and the timing will be the same as if an external clock at 4.096MHz is used. The conversion times shown in Table 7 are not exact times, but rather approximations. You can calculate the actual conversion times based on the number of clock periods shown in Table 11 (in most current datasheet). The two rightmost columns show the required number of clock periods for each conversion case.

If you change the clock frequency, the data rate is 1/fclk * number of periods required. The -3dB point will scale proportionally to the data rate for continuous mode. You will need to set the proportion to the true data rate and not the nominal (967.6/(1/fclk * 2072) for turbo mode and 2000sps).

Best regards,

Bob B

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About conversion time of ADS1120