• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 395 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM53600-Q1: Sync Frequency Range.

Dan Kemppainen
Prodigy 40 points
Part Number: LM53600-Q1

Support Path: /Product/Development and troubleshooting/

Hi,

Trying to evaluate an LM53600 for an application. 

We have an application where we sample data at 1.6Mhz, with an analog Bw of 150Khz. We were hoping to find a part we can sync with our sampling system in order to reduce power supply induced noise in the data. Figuring the part can be sync'd, we were going to pick a frequency in the datasheet rated sync frequency range of 1.9 to 2.3Mhz, so any aliased noise is not within the analog bandwidth of interest.

However, in testing of the Eval board, this part will sync and operate from ~500Khz to ~4.5Mhz. As far as I can tell, it will operate correctly within the voltage range in which sync mode operates synced to 1.6Mhz

It is worth nothing that this part is rated to drop operating frequency as input voltage increases. Under normal operation the eval board will drop to 1.0Mhz with the maximum 36V input voltage applied. 

What are the implications of Syncing this part to a 1.6Mhz frequency, where the rated datasheet sync range is 1.9Mhz to 2.3Mhz, even though the frequency automatically drops to 1.0Mhz during normal operation anyway?  

Thanks,

Dan

  • 0
    TI__Expert 6860 points
    Hi Glen ,

    You can sync the LM53600-Q1 at 1.6MHz .
    The reason for not allowing a wide sync frequency is the fact that the slope comp as well as loop comp is optimized for above AM band operation .

    The frequency shift at higher input voltage is intended to meet the min on time requirement .

    What is your input /output Specs for the design ?

    ---Ambreesh
  • 0 in reply to Ambreesh Tripathi
    Prodigy 40 points

    Hi,

    My name is Dan. Something is messed up in the account, as it has a co worker listed even though my name is correct in myTI profile. TI is supposed to be fixing this soon...

    Ok, so this part will operate at 1.6Mhz. We will plan on evaluating different frequencies between 1.6Mhz and 2.3Mhz.

    The input voltage is nominally between 9V to 18V, output is 5.5V at ~200mA to ~250mA. The voltage should be within the range that will allow sync to operate. Testing of the eval board verifies this part remains synced over our entire operating range. We will run a temperature sweep shortly.

    So, it's interesting this part is optimized to be completely out of the AM Broadcast band, but not the 160M amateur radio band. :) 

    Thanks for the information! 

    Dan