TMS320F280049: Difference between SDFM HLT and HLTZ

Brian Wang0

Part Number: TMS320F280049
Other Parts Discussed in Thread: AMC1306M25, AMC1306E25

Hi team ,

In F280049, I noticed we added a HTLZ comparator in addtional to HLT and LLT. What is the special consideration to add another comparator? Seems there is no such design in previous F28075 or F28377D.

Regards,

Brian

over 5 years ago

0 Manoj Santha Mohan over 5 years ago

TI__Guru 55700 points

Brian,

Your observation is right. We didn't have HTLZ comparator in F2837xD / F2837xS / F2807x devices.

This HTLZ comparator was added in F28004x devices based on customer feedback. HTLZ comparator is similar to HTL comparator expect, it cannot generate SDy_ERR interrupt. But HTLZ comparator events are connected to ECAP to measure the dutycylce (or) frequency of threshold crossing events.

Regards,

Manoj

0 Brian Wang0 over 5 years ago in reply to Manoj Santha Mohan

TI__Expert 5480 points

Hi Manoj,

One follow up question:

Assuming I am selecting Sinc3, OSR256, Shifting=0x0A, 16bit result. And the modulator is AMC1306m25 with +-250mV full scale input.

If I am get a result 9000(decimal), then the right input is :

9000/32768*250mV =68mV

Is that correct?

Regards,

Brian

0 Manoj Santha Mohan over 5 years ago in reply to Brian Wang0

TI__Guru 55700 points

Brian,

Here is the relationship between the applied input voltage and corresponding filter output from comparator filter and data filter.

Regards,

Manoj

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

TI__Guru 55700 points

Can you please close this thread if your questions are answered?

-Manoj

0 Brian Wang0 over 5 years ago in reply to Manoj Santha Mohan

TI__Expert 5480 points

One more question：

Let's take AMC1306E25 for example which support +-320mV input.

Then the Vclipping is supported to be 320mV or 640mV?

I did some verification, when I input a 180mV peak sin Wave to AMC1306, the peak value I got in SDFM is around 9200.

If we suppose the Vclipping is 320mV, Max fitler output is 32768(Sinc3, OSR256, 16bit), then the converted result is 90mV. Shall I change Vclipping to 320mV*2 ?

Regards,

Brian

0 Manoj Santha Mohan over 5 years ago in reply to Brian Wang0

TI__Guru 55700 points

Here are the calculations:

For Sinc3, OSR = 256: Max filter output value = 256^3 = 16777216

Vclipping = 320mv

Vpeak = 180 mv

Data filter theoretical value (32-bit value) = (180 mv / 320 mv) * 16777216 = 9437184

Data filter theoretical value (32-bit value) = 9437184 >> 10 = 9216

Regards,

Manoj

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

TI__Guru 55700 points

Can we close this thread? I believe all your questions have been answered.

-Manoj

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

TI__Guru 55700 points

Can you please close this thread and mark threads which answer your questions?

0 Brian Wang0 over 5 years ago in reply to Manoj Santha Mohan

TI__Expert 5480 points

Hi Manoj,

I believe I have already confirmed one of your replies above.

Regards,

Brian

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TMS320F280049: Difference between SDFM HLT and HLTZ