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LM25007: Input/output ripple voltage dependent on Ron of LM25007

Conor
Guru 13425 points

Part Number: LM25007

Hi,

When the Ron resistor is set to the standard 200kΩ, the input/output ripple voltage is 350mV. When the Ron resistor was set to 50kΩ, the ripple voltage was reduced to about 50mV.

Q1.
I checked the datasheet, but it doesn't specify the range of Ron.Please let me know if you have any information about the lower limit of Ron.

Q2.
Is it possible to calculate the appropriate value of Ron when the output current is 30-50mA?

~~Operating environment~~
・Input voltage 24V
・Output voltage 9.44V
・Output current 30 to 50mA

Thanks,

Conor

  • 0
    TI__Mastermind 22290 points

    Hi Conor,

    The Ron resistor sets the switching frequency, which affects the current ripple in the inductor, thereby affecting the output ripple voltage. Generally, inductors are sized for a given switching frequency to achieve 30%-50% current ripple of the maximum output current of the device. 

    I have included a link to the LM25007 Quick Start Calculator: https://www.ti.com/tool/LM25007QUICK-CALC

    This resource should help get you started.

    Best regards,

    Ridge