LM25141-Q1: LM25141-Q1 RES pin define

Lawrence He

Part Number: LM25141-Q1

Dear,

our client use LM25141-Q1, but we study datasheet and find RES pin look like enable hiccup mode, we test if output current overcurrent will enable hiccup mode( current limit threshold) SW was stop and output voltage was drop.

if we Pull up RES pin to VDDA, will shout down hiccup mode and output voltage was work.

General design LM25141-q1 use RES pin always pull down to GND?

schematic:

123F801_1A_1031_Final.pdf

If any suggestion, Please advise me.

Thanks,

Best regards,

Lawrence.

over 6 years ago

0 Katelyn Wiggenhorn over 6 years ago

TI__Genius 11040 points

Hi Lawrence,

Yes, you are correct. The RES pin should be pulled down through a capacitor to enable the hiccup mode for over current protection.

Please let me know if you have any additional questions.

In addition, I recommend using a minimum of 2.2uF at the VCC pin to ground. Also, you will want to calculate the value for Rsense using the equations on page 25 of the datasheet. There is a design calculator in the product folder. I recommend using this design calculator for comparison to your component choices.

Best Regards,
Katelyn

0 Chien Hsun Kuan over 6 years ago in reply to Katelyn Wiggenhorn

Prodigy 60 points

Hi Katelyn

In this case, the hiccup mode will be active when the loading is heavy.

So, i can't use hiccup mode in heavy loading?

Thanks for your reply.

LM5141ADESIGN-CALC.xlsx

0 Katelyn Wiggenhorn over 6 years ago in reply to Chien Hsun Kuan

TI__Genius 11040 points

Hello,

In this case the hiccup mode will be active when heavy loading. This means that you will be using hiccup mode in heavy loading. Does this make sense?

Thanks,
Katelyn

0 Chien Hsun Kuan over 6 years ago in reply to Katelyn Wiggenhorn

Prodigy 60 points

Hi Katelyn

I'm the designer of this case. As you say, in heavy loading using hiccup mode doesn't work.
Hiccup mode will be active when current exceed the limit threshold. Does current limit threshold can be design or calculate ?

Thanks for your reply.

0 Katelyn Wiggenhorn over 6 years ago in reply to Chien Hsun Kuan

TI__Genius 11040 points

Hello,

Thank you for clarifying.

Yes, you can set the current limit threshold with a resistor as described below:

Please let me know if you have any additional questions.

Best Regards,

Katelyn

0 Chien Hsun Kuan over 6 years ago in reply to Katelyn Wiggenhorn

Prodigy 60 points

Hi Katelyn

I still have some question can't understand.
I set Rsense to 0ohm to make sure Iout big enough.
In my case, Rsense can't be 0ohm ?

Thanks for your reply.
Kuan

0 Katelyn Wiggenhorn over 6 years ago in reply to Chien Hsun Kuan

TI__Genius 11040 points

Hello Kuan,

You will want to set Rsense to a value which will enable the current limit that you want. When the voltage drop across Rsense is 75mV, the device will enter hiccup mode.

Please let me know if anything remains unclear or if you have any additional questions.

Best Regards,
Katelyn

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LM25141-Q1: LM25141-Q1 RES pin define