TPS62740: I want to know about Iq of the device

Hello Vinayak,

Iq is defined as the current drawn by the IC in a no-load and non-switching but enabled condition (see attached app note for reference). Hence, it is not accurately say that I(in) = I(q) although the difference will be minimal. For the input current with higher load, it is more complicated because the device is switching continuously and I(q) will be less of factor anymore.

 If you want to know the I(in), it is better to use the efficiency data to calculate for it (see formula below). Do you have specific application condition (Vin, Vout, Iout) where you want to know the input current?

I(in) = (Vout x Iout) / (Eff x Vin)

Best regards,

Excel

Iq_slyt412.pdf

Hello Vinayak,

Just a soft reminder.

Do you have further queries?

Thank you.

Best regards,

Excel

hey Excel,

thanks for the reply. 

after reading your post I can understand that I(q) is not equal to I(in). 

can we say something like I(in)=I(out)+I(q) ?

correct me if I am wrong.

Yes I have gown through the application note that you have attached.

Hi Vinayak,

My colleague, Excel is currently on holiday. But I would be happy to answer your follow up question.

The formula in your last post for the input current is not correct for a Buck converter. It would be valid if you were using a LDO.

For Buck converters please stick to the formula Excel described : I(in) = (Vout x Iout) / (Eff x Vin). The I(q) component of the input current is already included in the efficiency factor (Eff).

Best regards,

Varun