LMZM23601: Internal Resistance Values for LMZM23601V3SIL

Kyle Goodrick

Part Number: LMZM23601
Other Parts Discussed in Thread: LM358

Hello,

I would like to use the LMZM23601 package to convert from 24V - 12V; However, currently only the "non-adjustable" LMZM23601V3SILR is in stock. I would prefer not to wait until the adjustable version is back in stock so I would like to force the 3.3V version to go to 12V instead. I believe this possible by adding a resistor divider from the output to the FB pin, but I need to know the internal resistance values to account for them in the external resistor divider values.

I couldn't find this information in the datasheet, do you have it available?

Thanks,

Kyle Goodrick

over 6 years ago

0 ChuckDSampson over 6 years ago

Intellectual 260 points

Use the external divider and then add a unity gain buffer. Then it won't matter what the internal impedance is. Use an emitter follower - a sot23 and a couple of 0402 resistors, or if you have room, use a LM358.

0 Kyle Goodrick over 6 years ago in reply to ChuckDSampson

Prodigy 200 points

Hi Chuck,

Thanks for the reply! That would definitely work; however, I've already completed the board layout and it only has the resistor divider in place. If I can fix the issue without making any changes to the board layout that would be ideal as its already been sent to the board fab.

Thanks again,

Kyle

0 Jimmy Hua over 6 years ago in reply to Kyle Goodrick

TI__Guru 50120 points

Hi Kyle,

The internal resistor divider values are as follows: Rfbt = 669.5k, Rfbb = 290.7k.

Theoretically you should be able to use an external resistor divider to create a 12V output application. However since this fixed output power module has not been tested for that condition, please evaluate and qualify the application for stability and proper operation in your system accordingly.

Regards.

Jimmy

0 Kyle Goodrick over 6 years ago in reply to Jimmy Hua

Prodigy 200 points

Excellent, Thanks Jimmy!

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LMZM23601: Internal Resistance Values for LMZM23601V3SIL