TPS56C215: Current Limit (Low side negative)

Hi Aaron,

Can I know why you want to get this NOC min and max value? At which application on your side, the NOC can be triggered?

I will look for these data at the same time.

Thanks,

Lishuang

Dear Lishuang

When choosing different inductance

Hi Aaron,

Sorry, I didn't found these min and max value until now.

You mean your part will work under FCCM, so you want to check whether the valley current will trigger NOC?

Actually, we usually use inductor current ripple (peak to peak) ILpp to determine the inductor value. We recommend to set the ILpp equals to 0.3-0.5 output max current, ILpp=LIR*Iomax, LIR=0.3-0.5. And, the current ripple can be calculated with ILpp=(Vin-Vout)*Vout/Vin/L/Fsw. So that we can get an inductor value.

If okay, you can share me the application conditions, I can help to check whether the inductor value is okay.

Thanks,

Lishuang

HI Lishuang

You mean your part will work under FCCM, so you want to check whether the valley current will trigger NOC?

=>yes

I understand ILpp equals to 0.3-0.5 output max current

datasheet Table 8-2. Recommended Component Values

Assuming VOUT=5V 800KHZ(FCCM) VIN=12V L= Recommended 2.2u, I reduce the risk of L(1u~1.5u)

Hi Aaron,

Checked that using 1uH inductor is also okay for your application, will not trigger NOC. The minimum inductor valley current is only up to -1.82A=-3.64/2A

Thanks,

Lishuang

HI Lishuang

I understand  minimum inductor valley current is only up to -1.82A=-3.64/2A

But I still don’t know NOC’s min max....

Hi Aaron,

Sorry, I checked but I still can't get the NOC min and max value.

What more, the NOC min or max value doesn't gated application uses.

Thanks,

Lishuang

HI Lishuang

Why does NOC max min not limit application usage. Does NOC limit the inductance value? (FCCM)

, How does HS-FET and LS-FET work when NOC?

Hi Aaron

    NOC will limit the min inductance value during FCCM. 

Typically LS-FET will be turned off when NOC is hit and current will flow through the HS Body diode. I will let Lishuang comment on the details of this device.

Regards,

Gerold

Hi Aaron,

I mean under your application conditions, NOC will not be triggered. I still can't get the min and max value of NOC.

Under FCCM, when NOC is triggered, LS-FET will be turn off and then after dead time, HSD will be on. 

Thanks,

Lishuang