LM5157-Q1: SW1,SW2 pin function

wenjun yang

Prodigy 70 points

Part Number: LM5157-Q1
Other Parts Discussed in Thread: LM5157, LM5175-Q1, LM61495, LM5175

Hi,TI experts

I see to LM5157 datasheet,SW1 SW2 have internal connection,I don't understand theirs function,as below image.

As I know ,Generally, Swithch node only connection Highside MOS and inductor.Could you help to me?

thank you

6 months ago

0 wenjun yang 6 months ago

Prodigy 70 points

Sorry ,errata to part number is LM5175-Q1

0 Brigitte 6 months ago in reply to wenjun yang

TI__Guru 58225 points

Hello wenjun,

For the high-side FETs, the switch node is the reference voltage for the driver signal. The gate or an NMOS needs to be higher than the source and the source of the high-side FET is the switch node.

Best regards,
Brigitte

0 wenjun yang 6 months ago in reply to Brigitte

Prodigy 70 points

Hello,Brigitte

Thanks for your kindly support

I am not understand clealy,could you help to explain more details.and I check LM61495 block diagram,it have no similar design,as below

thank you again

0 Brigitte 6 months ago in reply to wenjun yang

TI__Guru 58225 points

Hello wenjun,

LM5175 is a controller, so needs external MOSFETs. LM61495 is a converter with the FETs integrated. Please check the application section in the datasheet for the full schematic with external FETs.

Best regards,
Brigitte

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LM5157-Q1: SW1,SW2 pin function