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LM2596: How fast can you switch input pin 5 (ON / OFF)?

Damian Dygon
Prodigy 30 points
Part Number: LM2596

I designed a device that is powered by LM2596S-ADJ/NOPB. The input has a voltage from 5.2V to 8.4V and on the output we have a voltage range from 2.5V to 5.5V. I need the output voltage to be switched on at 100Hz and 50% fill. Can I connect TTL signal to input 5 (ON / OFF) with such frequency and will not damage the circuit? What is the maximum switching frequency of input 5 (ON / OFF)?

  • 0
    TI__Mastermind 23815 points
    Hi,

    I think 100Hz should be ok, unfortunately there is no maximum switching frequency of input 5 (ON/OFF) on the datasheet. So far i have not seen any damage report caused by switching ON/OFF pin too fast.

    Is there a specific reason why you would use this ON/OFF pin to have a pulse?

    Thanks
    -Arief
  • 0 in reply to Arief Hernadi
    TI__Prodigy 480 points

    Hi,

    I have attached some waveforms based on the conditions that you have specified.

    LM2596S-ADJEVM Pin 5 Waveforms.xlsx

  • 0 in reply to Arief Hernadi
    Prodigy 30 points

    Hi Arief,

    I also did not find any information about the maximum switching of input 5 (ON/OFF) on the datasheet.

    The output voltage from LM2596 powers the generator. Sometimes there is a need for the generator to work at a given supply voltage, but at intervals of 5 ms. That's why I want to quench the output voltage with the help of pin 5. I could use a transistor between the inverter and the generator to disconnect voltages but this is an extra chip. I preferred to use pin 5.

    Thank you for your help

    - Damian

  • 0 in reply to Eric Sato31
    Prodigy 30 points

    Thank you for the document you made for me. I also tested using oscilloscope what is happening with the system. To a large extent, the maximum frequency depends on the power consumption from the LM2596 output. If the curent consumption is too low, the output voltage will not go down to zero (waveform #1, #3 in your document). This problem can be solved by adding a transistor to the LM2596 output, which discharges the output capacitor. I was just wondering if switching 5 (ON / OFF) at 100Hz would not destroy LM2596.

    Thank you very much for helping Eric