LM5008A: NOPB Switch Node Question

Denny Huang

Expert 7170 points

Part Number: LM5008A

Dear team

Customer have some question, could you give some recommend?

We found the following problems when measuring Switch nodes.

As shown in the attachment, glitch will occur under full load, but no glitch occurs under light load.

Can you help to confirm what the problem is?

Full loading :

Ch1:Vin

Ch2:SW

Ch3:ISW

light loading :

Ch1:Vin

Ch2:SW

Ch3:ISW

Many thanks

Denny

over 3 years ago

0 Daniel Li14 over 3 years ago

TI__Mastermind 27030 points

some assuption:

1. it is related to the diode capacitor resonant with parasitic inductor on the PCB. so it maybe relate to the layout and diode feature.

if VIn is lower, whether the glitch will become a overshoot at full load?

0 Denny Huang over 3 years ago in reply to Daniel Li14

TI__Expert 7170 points

Hi Daniel

I appreciated your reply.

1. if VIn is lower, whether the glitch will become a overshoot at full load?

- I will ask customer and reply to you.

I use the EVM and also find the glitch on switch node.

Do you find same glitch on EVM(LM5008AEVAL)?

Could you give some recommend?

Many thanks

Denny

0 Daniel Li14 over 3 years ago in reply to Denny Huang

TI__Mastermind 27030 points

Hi Denny：

I think the glitch is made by the diode capacitor resonant with parasitic inductor , if you also see in EVM, It should be a normal waveform and what's impact to customer system?

Thanks

Power management

Power management forum

LM5008A: NOPB Switch Node Question