LM5176: LM5176 Jitter Unstable

Hugo Liu

Genius 5095 points

Part Number: LM5176

Hi Sir,

Our customer used the LM5176, But Jitter Unstable.

Is this waveform normal? or How to improve this issue?

Vin=24V Vout=12V Iout=10A(Ch1=SW CH4=IL)

over 5 years ago

0 Youhao Xi over 5 years ago

TI__Guru 68675 points

Hi Hugo,

It seems you turned on the frequency dithering function. To stop it, you should ground the DITH pin.

Thanks,
Youhao Xi

0 Hugo Liu over 5 years ago in reply to Youhao Xi

Genius 5095 points

Hi Sir,

We are change DITH Pin to GND, this issue is solve.

But our customer have other issue for LM5176,

If LM5176 Light load maybe is 0A, then inductance temperature 50degree C.

Is this normal?

Hugo

0 Garrett Roecker over 5 years ago in reply to Hugo Liu

TI__Mastermind 21720 points

Hi Hugo,

Is the LM5176 operating in CCM?

Thanks,

Garrett

0 Hugo Liu over 5 years ago in reply to Garrett Roecker

Genius 5095 points

Hi Sir,

Yes, our customer is set CCM mode & with Hiccup enabled resistor 93.1k to GND.
We are see the Datasheet Figure 19 in Hiccup mode current limit IL max=16~17A.
is this mode create an 50degree C on inductance ?

Hugo Liu

0 Garrett Roecker over 5 years ago in reply to Hugo Liu

TI__Mastermind 21720 points

Hi Hugo,

In CCM operation and at no load there are still AC core losses of the inductor. There will still be winding losses as well. Both of these will contribute to the temperature rise.

Also please ensure that both the switch nodes are operating normally.

Thanks,

Garrett

0 Hugo Liu over 5 years ago in reply to Garrett Roecker

Genius 5095 points

Hi Sir,

Thank you very much.

Hugo

Power management

Power management forum

LM5176: LM5176 Jitter Unstable