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LMK61E0M: Frequency Range

Jiahui Gao
Expert 7050 points
Part Number: LMK61E0M
Other Parts Discussed in Thread: USB2ANY, LMK6C, SN74LV4040A

Hi team，

I am looking for programmable OSC and found that LMK61E0M might be a good option for me. I have a question on it and want to double check with you. In the datasheet, page10, chapter 8.3.4, it looks like if I configure P=5 and OUTDIV = 256, I can get an output frequency around 4MHz. Does it mean that the output range of this is about 4-200MHz? I notice that for output frequency greater than 50MHz, it is fast mode, are there any specs difference between fast mode and "slow mode"?

Besides that, I am looking for an OSC/clock generator with output frequency from several MHz to about 100Mhz. LMK61E0M is the one that best fit my demand, but it looks so complicated and high end. Its step can be 10^-8MHz but my need is about 1MHz. Do you have recommendation on my options?
For the slow mode, so you have the slow rate specs to show how bad it is?

Could you help?

Best regards,

Vivian

  • 0
    Prodigy 120 points

    Hello Team

    Vivian helped me posted this question and I want to specify my need in here.

    I want to find a chip which is able to output different frequencies by configuring the external circuit. I don't need the step to be very small. For example, there are 10 bits parallel inputs (0/1) and there is an internal oscillator (for example 50MHz). Maybe 10 bits are all den or num and den. The output square wave clock frequency = 50*num/den or f=50/den. Are there any chips like this? I don't need the complicated programmable osc and I just need a simple one like what I mentioned above. It is similar to NCOs but NCOs are outputting sine waves

    Thanks

  • 0 in reply to Yifu Chen
    TI__Genius 12130 points

    Hi Vivian and Yifu, 

    Note that we have a programming tool called TICSpro that makes programming the LMK61E0M much easier, you can enter a target frequency and the program will optimize the rest of the configuration. If applicable, it can also directly program the device using USB2ANY. I was able to generate configurations as low as 5 MHz and program them to the EVM with R22 [7:6] still set to 00, so the device should still be programmed in fast mode. 

    Another option is to use a fixed-frequency oscillator that operates at a higher frequency, such as LMK6C, then divide it down with a pin programmable divider or binary counter. This will result in worse performance, but in the past we have recommended the SN74LV4040A if this is isn't a concern. 

    Regards, 

    Connor