LM2650 SIA/SOA Calculation

PAN-M

Dear All.

"The value of the resistor connected between SIA and ground programs the sleep-in threshold."
There is written in the datasheet.
Do you have arithmetic expression about SIA/SOA?

Regards,
PAN-M

over 8 years ago

0 Brani Dubocanin over 8 years ago

TI__Expert 4100 points

Hello Pan-M,

We are looking into this and will get back to you soon.

Regards

Brani

0 PAN-M over 8 years ago in reply to Brani Dubocanin

Mastermind 8375 points

Could you please feedback to me.
Regards,
PAN-M

0 Brani Dubocanin over 8 years ago in reply to PAN-M

TI__Expert 4100 points

Hi Pan-M,
Apologies for delayed reply.
We will be getting back to you very shortly.

Regards
Brani

0 Brani Dubocanin over 8 years ago in reply to PAN-M

TI__Expert 4100 points

Hello Pan-M,

Unfortunately it is taking longer than anticipated to get to the bottom of this question.

We are working on it will get back to you as soon as we have an update.

Best regards

Brani

0 PAN-M over 8 years ago in reply to Brani Dubocanin

Mastermind 8375 points

I am waiting for your answer.
Regards,
PAN-M

0 Brani Dubocanin over 8 years ago in reply to PAN-M

TI__Expert 4100 points

Hi Pan-M,

Thank you for your patience.

Here is equation for calculating Rsoa==> Isout = 5.2235 * Rsout ^ -0.65

where Isout is load current at which the device should exit low power hysteretic mode and enter PWM mode. As mentioned in data sheet having larger Rsoa results in lower threshold value.

As far as Rsia is concerned, there could be range of values depending on what is considered low power mode. We recommend using Rsia=33kOhm for very light load operation (<1mA). This value provides for device operation at fsw~1kHz with ~50-60mA output load.

Hope this helps.

Best regards

Brani

0 Brani Dubocanin over 8 years ago in reply to Brani Dubocanin

TI__Expert 4100 points

Hi Pan-M,

In addition to the previous post, here is calculation for Isin and Rsia.

The equation to use is: Isin = [(1.26/Rsia) + 5e-6] * 1e3

Regards

Brani

0 PAN-M over 8 years ago in reply to Brani Dubocanin

Mastermind 8375 points

Thank you for support, Brani.
I will send this information to our customer.
Thanks and Regards,
PAN-M

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LM2650 SIA/SOA Calculation