UCD3138: Ramp in Peak Current Mode

Rutskoy Andrey

Part Number: UCD3138

Hello!

Can you explain how UCD convert data from the output of the filter to DAC module when we use Ramp in Peak Current Mode Control?

Ramp rate is 32 ns. Step is 50 (write 52000 in 8.10 bit format).

Filter output has a format 14.4

DAC value = Filter output value (14 H bits) – DAC_STEP value (8 bits) and than Rsh on 4 as DAC has 10 bits (without dithering) . This value update every ramp step (32 ns).

Is it correct?

must DAC_value in Memory Debugger show the value after subtraction?

over 4 years ago

0 Sean Xu over 4 years ago

TI__Genius 14580 points

Hi,

You are almost right. Here are some correction: Filter output value is 18 bits, it is left shifted 6 bits, then the number is subtracted by DAC_STEP. the result is right shifted by 14 bits. Every 32 ns, the DAC is updated.

Regards,
Sean

0 Rutskoy Andrey over 4 years ago in reply to Sean Xu

Intellectual 465 points

Dear Sean,

Thank you for the support! And one more related question.

CPCC

How value form Frond End compare with NOM_CURRENT_LOWER/UPPER (10 bits) and MAX_CURRENT_LOWER/UPPER (10 bits). Can you also explain the way.

Thanks

0 Sean Xu over 4 years ago in reply to Rutskoy Andrey

TI__Genius 14580 points

Hi, Rutskoy,

ABS_VALUE is used for comparison. You can read programmer manual about how to use this register.

Regards,

Sean

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UCD3138: Ramp in Peak Current Mode