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LM5001: Can the LM5001 be externally clocked at 2.1 MHz?

Les Wolff
Prodigy 40 points
Part Number: LM5001
Other Parts Discussed in Thread: LM5022

I'm using the LM5001 at 1.2 MHz and it is interfering with nearby AM radio receivers.  Can the LM5001 be externally clocked at a higher frequency than the published 1.5 MHz?  If not, is there a pin compatible part that can be clocked over 2 MHz?

  • 0
    TI__Guru* 78170 points
    You can make the LM5001 to sync to an external clock via the RT pin, as described in Section 7.3.3 in the datasheet. However, we do not recommend to sync it to greater than 1.5MHz because it was never validated with the IC and we cannot predict any potential issue. If it is interfere with the AM band, lower the frequency to below the AM band is another option.
  • 0 in reply to Youhao Xi
    Prodigy 40 points
    I used 480 KHz and had interference from the harmonics at 960 and 1440 KHz. Does TI offer a part similar to the LM5001 that can be used at 2 MHz? I am using the LM5001 as a buck mode negative converter (-40V in, -15V out). Other than the AM band interference, it works perfectly for the application.
    Thanks in advance for your assistance!
  • 0 in reply to Les Wolff
    TI__Guru* 78170 points
    Really appreciate your considering of using our device in you design. You can try 2MHz but I cannot officially recommend it because it is beyond our datasheet recommendation. The solution that I can recommend is to add some EMI filter to prevent the interference.
  • 0 in reply to Youhao Xi
    TI__Guru* 78170 points
    To add: you may also consider the LM5022, which is a controller and requiring an external FET, but it can be switched at 2MHz.