UCD90160A: Clock Trim

Aaron Spaete

Part Number: UCD90160A

Team,

My customer has the following question:

I have a few questions related to the UCD90160A that I could use some help with. Specifically related to the RUN_TIME_CLOCK_TRIM command.

We are using the watchdog function in the UCD90160A device and my software team has informed me they've seen a fair amount of "error" on some devices (up to 2.5%). It seems the RTC trim command does affect the watchdog timeout. Can you confirm this is the case (ie is this actually trimming the internal oscillator)? Also when trying to use the SMBus debug tool to read/write this command, I'm seeing very different values read back from the device after writing a D8h command. Can you provide any clarification on the format of this command?

Regards,

Aaron

over 5 years ago

0 yihe over 5 years ago

TI__Guru 65650 points

All timers are from the same internal clock source. RTC_TRIM would increase or decrease the internal clock source to sync with the external clock source.

The D8 command(section 10.9 of http://www.ti.com/lit/ug/slvu352g/slvu352g.pdf )takes the two bytes data as liner11 format which is defined at section 2.2 of http://www.ti.com/lit/ug/slvu352g/slvu352g.pdf

For example: -0.35% can be represented as 0xAD33, where the X is the MSB 5 bit,Y is the LSB 11 bit

so X=-11 and Y=-717, -717*2^(-11) = 0.35.

Regards

Yihe

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UCD90160A: Clock Trim