Hi,
Could you tell me about TPS7A8300 VDO spec?
Customer is considering the following conditions:
Vin=xx, Vbias=3.3V, Vout=1.2V, Iout=1.5A
Customer want to adjust Vin according to the Vdo spec.
Please tell me the minimum input voltage you recommend.
And In this case, is the datasheet value applicable (Vin(min)=Vout + 0.125V)?
Could you give me your advice?
Best Regards,
Yusuke
Hi Yusuke,
I would like to make you aware of TPS7A83A which is the pin-to-pin compatible next generation of TPS7A8300. One of the biggest advantages of TPS7A83A is that there is no sequencing requirements when using a Bias rail.
As you can see in Figure 21 of the TPS7A83A datasheet, for the lower input voltage range where your application will be, dropout is relatively flat with regards to input voltage.
Figure 23 shows that dropout is linear with respect to output current.
When we put this information together we can estimate that the max dropout in your application will be:
Vdo1.5A / 1.5 A = Vdo2A / 2 A
Vdo1.5A / 1.5 A = 125 mV / 2 A
Vdo1.5A = 93.75 mV
Temporarily ignoring the contribution of Vin per Figure 21, this means that a Vin of 1.295 V should be adequate to achieve regulation at your application conditions. If we wish to add a little more margin to our calculations to account for the slight increase in dropout due to Vin shown in Figure 21, our minimum Vin would be 1.3 V.
Very Respectfully,
Ryan
