LMZM33603EVM: About Synchronization switching jitter

Tsukui Yusuke

Guru 21930 points

Part Number: LMZM33603EVM
Other Parts Discussed in Thread: LMZM33603, LMZM33606

Hi,

Customers are evaluating LMZM33603 using EVM.
There is question about the evaluation results.

Evaluation condition is :
Vin=24V, Vout=5V, Synchronization input : 400kHz(High=5V, Low=0V)

The synchronous frequency of 400 kHz was able to operate normally.
However, switching jitter is large.

Oscilloscope measurement result of envelope mode was 50 nsec.
Customers want to reduce to jitter.
Could you tell me how to improve jitter?

Best Regards,
Yusuke

over 4 years ago

0 Jimmy Hua over 4 years ago

TI__Mastermind 47060 points

Hi Yusuke-san,

Can you describe your loading condition. When the system is in between DCM and CCM , the switch node may be abit jittery. This is similar to my explanation that I provided for the LMZM33606.

I've also included an app note that may help provide reference to jitter. Do note that this power module uses a peak current mode IC. The is not much that can be done since the inductor may be oversized to account for different output value conditions and is more susceptible to jitter.

Regards,

Jimmy

0 Jimmy Hua over 4 years ago in reply to Jimmy Hua

TI__Mastermind 47060 points

Hi Yusuke-san,

Any update on this?

Regards,

Jimmy

0 Tsukui Yusuke over 4 years ago in reply to Jimmy Hua

Guru 21930 points

Jimmy-san ,

Thank you for your kind support and message.
I haven't received a response from them yet.
I urge it to the customer.

Best Regards,
Yusuke

0 Tsukui Yusuke over 4 years ago in reply to Tsukui Yusuke

Guru 21930 points

Jimmy-san ,

Thank you for your kind support.
Customer changed the load and checked the jitter.
However, the magnitude of jitter did not depend on the load.
Customers want to reduce jitter as much as possible.
Are there any good methods for that?

LMZM33603 waveform.pdf

Best Regards,
Yusuke

0 Jimmy Hua over 4 years ago in reply to Tsukui Yusuke

TI__Mastermind 47060 points

Hi Yusuke-san,

Let me take this EVM to the lab and proper operations for you. I'll try to get back to you by the end of tomorrow.

Regards,

Jimmy

0 Tsukui Yusuke over 4 years ago in reply to Jimmy Hua

Guru 21930 points

Jimmy-san,

Thank you for your strong support.
I'm looking forward to hearing from you.

Best Regards,
Yusuke

0 Jimmy Hua over 4 years ago in reply to Tsukui Yusuke

TI__Mastermind 47060 points

Hi Yusuke-san,

I tested the SYNC functionality on the an EVM with the internal IC of this power module. The jitter as a result of SYNC is still there with similar measurements of roughly 25-30ns jitter. I believe this is part of the IC and unfortunately this might not be something that can be modified.

Regards,

Jimmy

Power management

Power management forum

LMZM33603EVM: About Synchronization switching jitter