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# Calculate stepss for PowerSTEP01 (and L6480)

Senior II

Hi, I am currently implementing software/firmware for the PowerSTEP01 chip and discovered a inconsistency in data sheet https://www.st.com/resource/en/datasheet/powerstep01.pdf. For parameter INT_SPEED (section 11.1.11 in datasheet) the equation does correspond to the stated limits.

It says:

i.e. steps/s = INT_SPEED × (2^−18) ÷ (250×10^−9)

• For smallest possible INT_SPEED=1 you get the minimum value:

steps/s = 1 × (2^−18) ÷ (250×10^−9) = 15.25

• For largest possible 14 bit value you get the maximum value:

step/s = (2^(14+1)−1) × (2^−18) ÷ (250×10^−9) = 499984.74

But according to datasheet equation results should be in range 0 < steps/s < 976.5.

So what is correct?

NOTE: This question and answer originated from a customer support case which was handled by us. We regularly review support cases and add any helpful ones here for all to benefit from.

1 ACCEPTED SOLUTION

Accepted Solutions
Senior II

You are right, thank you for raising this issue. In fact, there is a typo in datasheet. The correct formula is:

i.e. steps/s = INT_SPEED × (2^−26) ÷ (250×10^−9)

Same mistake applies also to L6480 datasheet :persevering_face: , but at least L6470 datasheet is correct 🙂 . Control logic is the same for all 3 devices.

Mistake in datasheet will be corrected asap. Sorry for the inconvenience.

2 REPLIES 2
Senior II

You are right, thank you for raising this issue. In fact, there is a typo in datasheet. The correct formula is:

i.e. steps/s = INT_SPEED × (2^−26) ÷ (250×10^−9)

Same mistake applies also to L6480 datasheet :persevering_face: , but at least L6470 datasheet is correct 🙂 . Control logic is the same for all 3 devices.

Mistake in datasheet will be corrected asap. Sorry for the inconvenience.

Associate II

I have just downloaded the 'latest' datasheet and this change has not been implemented