RTOS/TMS320F280041: F280041 Sigma delta interface spec for confirm.

Curry Huang

Part Number: TMS320F280041
Other Parts Discussed in Thread: SN74LVC1G14

Tool/software: TI-RTOS

Hello team,

My customer is planning to use F280041 + AMC1306 to achieve 3 phase current sensing. But there is a spec confusing us in Dout hold time.

As for Sig-Delta interface, AMC1306 spec for min hold time is 3.5ns, but F280041 required the Dout hold time min is 5ns.

This means host side needs longer time for hold on than device side, Do you think there is any potential risk? How to consider filter module for this spec definition?

Another question is about the delay time for Sigma delta filter module? Do we have any data or calculation for this delay time with filter bandwidth?

thanks,

Best regards,

Curry Huang

over 5 years ago

0 Manoj Santha Mohan over 5 years ago

TI__Guru 55700 points

Huang,

I need to check with SD-modulator team about set-up / hold time requirement. I hope to get back to you by Sep 26, 2018 on this subject.

What do you mean by delay time of SDFM module? Are you talking about latency (or) data rate of SDFM? If so, please check "Data Rate and Latency of the Sinc Filter" section in SDFM chapter of TRM. SDFM filter resolution depends on Filter type, OSR setting and SD-modulator operating frequency. This information is found in Figure 58. "Measured Effective Number of Bits versus Settling Time" and Figure 55. "Measured Effective Number of Bits versus Oversampling Ratio".

Regards,
Manoj

0 Curry Huang over 5 years ago in reply to Manoj Santha Mohan

TI__Prodigy 310 points

Manoj,

Thanks for your reply.

Please help me double check the hold time spec.

Yes, I mean the latency of SDFM.

0 Curry Huang over 5 years ago in reply to Manoj Santha Mohan

TI__Prodigy 310 points

Manoj, any updates for this case?

thanks,

Curry Huang

0 Manoj Santha Mohan over 5 years ago in reply to Manoj Santha Mohan

TI__Guru 55700 points

Huang,

No, I will still working with AMC1306 engineer to get clarification. Please give me couple of more days.

Regards,
Manoj

0 Manoj Santha Mohan over 5 years ago in reply to Manoj Santha Mohan

TI__Guru 55700 points

Huang,

AMC1306 and F280049 SDFM are incompatible with one another.

AMC1306 modulator changes data on rising edge but F280049 SDFM expect the data to change on falling edge.

Regards,
Manoj

0 Curry Huang over 5 years ago in reply to Manoj Santha Mohan

TI__Prodigy 310 points

AMC1306 modulator changes data on rising edge but F280049 SDFM expect the data to change on falling edge.

>> so AMC1306 and F280049 SDFM is incompatible??

0 Manoj Santha Mohan over 5 years ago in reply to Curry Huang

TI__Guru 55700 points

Yes, they are incompatible.

0 Curry Huang over 5 years ago in reply to Manoj Santha Mohan

TI__Prodigy 310 points

Hi Manoj,

F280049 SDFM expect the data to change on falling edge.

>> so if we use an inverter buffer, saying using SN74LVC1G14, can it meet the timing required? Anything we need to pay attention if that?

thank you!

best Regards,

Curry Huang

0 Manoj Santha Mohan over 5 years ago in reply to Curry Huang

TI__Guru 55700 points

Curry,

You need to make sure the timing delay caused by the interter doesn't vioate SDFM timing requirement. If it doesn't then you can use AMC1306 + SN74LVC1G14 + F280041.

Regards,
Manoj

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RTOS/TMS320F280041: F280041 Sigma delta interface spec for confirm.