DAC8760: DAC8760 Readback Mode Timing

ttd

Part Number: DAC8760

Hi Joseph,

I have additional question related to following E2E you suuported.

DAC8760: About DAC8760 Spec - Data converters forum - Data converters - TI E2E support forums

Regarding the readback mode timing diagram in Figure 7.2 of the datasheet,
I previously received a response that a NOP frame is performed after a read frame.

By what point does DIN need to be low?

Would it be okay if it was before the SDO data was confirmed (before the rising edge of SCLK)?

Best Regards,

ttd

6 months ago

0 Joseph Wu 6 months ago

TI__Guru** 100735 points

ttd,

The important time for the DIN being low is the data setup time for the first SCLK. This is the equivalent to t16 which is 5ns before the rising edge of the SCLK.

For the readback of the register, the first 8 bits are don't care bits, so they don't need to be confirmed. In the end you only need the data from DB15 down to DB0.

Joseph Wu

0 ttd 6 months ago in reply to Joseph Wu

Mastermind 9335 points

Hi Joseph,

Thank you for your reply.

I have additional question.

Regarding the CRC output by the DAC during readback with CRC enabled:

Is it correct to understand that the result of applying the CRC-8-ATM algorithm to the upper 24 bits of data (including the don't care bits) output by the DAC is then output as 8 bits? Or is the data calculated using the 16 bits excluding the “don't care bits” that is output?

Best Regards,

ttd

0 Joseph Wu 6 months ago in reply to ttd

TI__Guru** 100735 points

ttd,

The CRC output is calculated from the previous 24 bits of data on the output. You would not exclude the don't care bits from the first 8 bits.

Joseph Wu

0 Joseph Wu 6 months ago in reply to Joseph Wu

TI__Guru** 100735 points

ttd,

Also, I wanted you to remember that the CRC has some unusual behavior. I had described this in the previous thread. You can find this description in this post:

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/1545066/dac8760-about-dac8760-spec/6002783

Joseph Wu