data/text/DLP2/887790

SM72442: question of I2C write data sequence.

Part Number: SM72442 in the datasheet of SM72442, for I2C write sequence there is 8 data bytes from frame 4 to frame 11. if frame 4 is data 1, why frame 11 is data 7(it should be data 8)? ,and one of I2C registers is 7 bytes long, why write 8 bytes data?

Hi i think it should be a typo. the data bytes is 7 instead of 8 from frames 5 to 11. I don't have EVM as it is quite old device. do you have an IC to try?

thank you so much. I am writing the software , so should i think the frame 11 is no need. please check page 14 of the datasheet of SM72442, NOW the hardware is not ready ,so i cannot test on the software ,but i want to write the right sofeware.

Hi, i think you are right. the data is from frame 4~ frame 10. I will also try this after getting the EVM.

Hi User, sorry for the late, but i'm still waiting for the EVM. thanks for your understanding.

Hi User, i got the EVM, and will try the I2C. what is the status in your side?

Hi, your understanding is correct. the data frame should be from 4 to 10. the 11 is not need. let me know you see issue.

THANK YOU for your work, I think this problem is fixed, now I change this chip to 72445 , 72442 need so high frequency PWM ， my NMOS can not work well, MY another question ,do you have saw it?

Hi Sorry, which question do you refer to?

IT is difficult to Calculate the value of inductance and capacitance, I have find the ripple of No load output Voltage achieved 20%, the inductance is 22UH capacitance is one single Electrolytic capacitor of 330uf。 the load is BLDC motor ， not charge for battery, is some problem ?? can you check for me ,of course if you have time, thank you if you have time I will send to the Schematic diagram, now I hope you just give some advice about how to select the inductance and capacitance. best regard

could you share the schematic? also share the VIN and VOUT waveform to show that your observation.