Consumption with TPS 61222

I think you may turn to below pdf to find out what IQ stands for in the D/S.

http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slyt412&fileType=pdf

In fact,the no load current consumption is not the IQ in datasheet.

What's the supply voltage of your microcontroller?

Hello thanks for reply. I will read the pdf. The supply voltage of my microcontroller is 3.3V.  Now, I put the microcontroller in power down mode and wakes up with a RTC. The consumption is about 10 uA( only microcontroller and RTC). I f I use the TPS 61222 the consumption is about 50uA.
Thanks,
Regards.

Your battery voltage is 3.7V and your MCU supply is 3.3V ,so I think you should use a buck converter or a LDO

Hello, the battery voltage go from 3V to 4.2V.  I use this IC because if  Vbat =3V the LDO not work fine. I would like the system to work until the battery voltage is 3V.
If I use the LDO, the system stops working when the battery voltage is below 3.3V. What is better?  work until Vbat = 3V or  Vbat=3.3V. Because I would like to extend as much as possible the performance of the system.

Thanks,
Regards.

What's the peak current when your MCU is runing at full load?

Maybe you can use buck-boost,for example TPS63010,it converter down voltage when Vin is larger than Vout and boost voltage when Vin is less than Vout.

My peak current is about 100mA and 30uA when system is in sleep mode. I think it is better to use the LDO, because, the consumption is less and the battery life will be greater.

Thanks, Regars.

if you use LDO,they your system may not work with 3V battery voltage.

So,I think you can consider using buck-boost.

The no load consumption of LDO should be same level with the buck-boost.Can you suggest which LDO you plan to use?

The buck-boost, TPS6301x, has a consumption about 40uA. The LDO as TPS727xx has a 7.9 uA. I could use the TPS72733. One question, Which is the consumption of buck-boost TPS6301 with load? because the consumption, with load ( microcontroller + RTC) , of TPS61222 is about 50uA, in sleep mode, and with the LDO is about 18uA(microcontroller + RTC + LDO) in sleep mode, more or less.

Thanks,

Regards.

The no load current(not IQ) of TPS61031 could be larger than 40uA(IQ),because you need to consider the current going through the feedback divider.The value of no load current also depends on your feedback resistor value.

Yes,the LDO has smaller IQ ,but you may have to turn off your system at 3.4V(LDO has drop out voltage ~65mV).

Does your system keep in standby mode most of the time?If not,40uA difference is not that important.

To sum it up,if you need to run your system at 3V battery voltage, you should use buck-boost otherwise LDO is good.

The system will be in standby 10 minutes or more, wakes and it sends a message. Then I think the ldo is the better solution.

Thanks,

Regards.

It is all an engineering trade off  At your light loads during standby, an LDO is more efficient.  As your load increases to 100 mA, the efficiencies even out.  At higher currents, the converter will gain advantage.  For your case, so you want the higher efficiency of the LDO along with a low end operating range of about 3.4 V, or the lower efficiency of the converter that will supply 3.3 V with input voltage down below 3.0 V?

Hello, in my case i prefer to work in this range, 3.3V-4.2V, because the voltage of the battery voltage is going from 4.2V up to 3V. Then the solution is to use the LDO or i am wrong.

Thanks,

Regards.

Hello, thanks for reply. It has been helpful.
Thanks,
Regards.