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LP3943: tolerance in frequency

Jan Bock

Intellectual 2800 points

Part Number: LP3943
Other Parts Discussed in Thread: LP5861, LP5018

Hi Team

can you please help:

We use the LED driver LP3943.
Here we have noticed two things during the commissioning measurement
1. in the upper frequency range fine frequency changes are not possible...e.g. 100Hz
o Value 0 in PSC0 register -> 160Hz
o value 1 in PSC0 register -> 80Hz
2nd frequency deviates from the set value
o 160Hz set -> measured: 152Hz
o 80Hz set -> measured: 76Hz

This resulted in the following questions for us:
1. is the frequency really adjustable in such large steps in the upper frequencies or do we have a thinking error? Would 100Hz somehow be possible with the module?
2. are these really the tolerances, so that we never reach the 160Hz or do we have possibly an error in the software!

Thanks

Jan

over 1 year ago

+1 Ives Li over 1 year ago

TI__Expert 6440 points

Hi，

The frequency is calculated by below：

F = 160/（PSC + 1），so 100Hz cannot be achieved.

And if you set PSC0 = 0 and map the LEDs you want to use dim0，the frequency for these LEDs should be 160Hz.

If you want to achieve higher dimming frequency，you can look at our new device：LP5018/LP5861

Thanks！

0 Jan Bock over 1 year ago in reply to Ives Li

TI__Intellectual 2800 points

Hello Ives,

thank you for the reply. What is about the second question about the tolerances. Usually it should not vary like this at room temperature:

Jan Bock said:
2. are these really the tolerances, so that we never reach the 160Hz or do we have possibly an error in the software!

Thanks

Jan

+1 Ives Li over 1 year ago in reply to Jan Bock

TI__Expert 6440 points

Hi Jan，

There is an deviation between devices，so the actual frequency maybe not exact 160Hz.

Thanks！