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TIDA-010074: about the LM5164DDAT

user6501051
Intellectual 825 points

Part Number: TIDA-010074
Other Parts Discussed in Thread: LM5164

Dear TI expert,

In this example, RON connect R148 1.0M, if let's the power supply work in DCM mode? How to calculate the R148 is 1.0M value?

in normal work mode, the MCU let's turn on the Q39 2N7002, let's work frequency in =5*2500/115=108K

but in design file in page 7, the Ron is 125K, but in schematic the Ron is 115K

  • 0
    TI__Expert 6670 points

    Hi 

    Please allow us sometime to look at the schematic and provide you feedback. We will answer in the next 2 days.

    Thanks,

    Robert 

  • 0
    TI__Expert 3356 points

    Hi, 

     R148 is to decrease LM5164 switching frequency to a quite low value to decrease consumption. So Q39 is off in sleep mode and on in normal mode. I didn't calculate the 1M, it is more like a experience value. You can modify it to fit your design. 

    Regarding Ron, the formula in design guide is correct. 115k gives buffer in case Q39 is not completely turned on with 3V gate-source voltage.

    Best Regards,

    Ryan Tan