LMR14050-Q1: LMR14050 Clock Sync issue?

Julio Apps

Part Number: LMR14050-Q1
Other Parts Discussed in Thread: LMR14050

Hi Team,

We are seeing an issue with the LMR14050-Q1 clock sync functionality. During start up my customer is using an external clock source that is in High-Z initially. There are other DC/DC converter's that just revert to the Resistor setting set on RT/SYNC but the LMR14050 devices fails to operate correctly. There is a 12.7kOhm resistor from RT/SYNC pin to ground and a 33Ohm resistor inline with RT/SYNC pin and the clock source. After removing the 33Ohm resistor the device starts to work properly. Any idea of what could be happening and have you seen this before in other deigns with an external clock SYNC?

over 6 years ago

0 Samuel Jaffe over 6 years ago

TI__Mastermind 25590 points

Julio,

If the device was truly high-Z I'd expect removing the 33 ohm to make no difference. I'm thinking the high-Z may have a glitch or some impedance that we're not aware of. Can you probe the RT/SYNC pin during startup to see what the voltage is during this condition?

Thanks,

-Sam

0 Julio Apps over 6 years ago in reply to Samuel Jaffe

TI__Expert 3665 points

Sam,

I was thinking the same thing, i am waiting for a scope plot from the engineer working on this. I also recommended trying the low impedance recommendation from the datasheet. Ill post an update once i receive more information.

0 Samuel Jaffe over 6 years ago in reply to Julio Apps

TI__Mastermind 25590 points

Julio,

Let me know when you get an update.

-Sam

Power management

Power management forum

LMR14050-Q1: LMR14050 Clock Sync issue?