TPS62086: Operation at low currents

Hello Asael,

Thank you for reaching out.

I think we are already discussing about the same device in another threat, but the concern is different. The Vin and Vout specifications look similar. Is it the same project?

FYI ((+) TPS62086: Wrong output after a battery is drained and charged. - Power management forum - Power management - TI E2E support forums)

TPS62086 operates on DCS-Control topology. During the light load conditions, it operates in PFM mode to achieve better efficiency.  

You can find more about DCS-Control in this APP note (High-efficiency, low-ripple DCS-Control offers seamless PWM/pwr-save transitions).

Thank you,

Regards,

Moheddin.

Yes, it is the same project but two different concerns. Let us check the app note.

But for now, I can ask the following, in the graphs we have in TI webench the efficiency is less than 90% for currents greater than 1 mA, we cannot see what happen for current less than 1 mA, so can we assume we will have same efficiency (more than 90%) for currents less than 1 mA, for current in micro amps?

Thanks, and regards

Hello Asael,

Thank you for the conformation about the project.

Right now, I don't have information about the efficiency for TPS62086 at very low load current. I could not guaranty the same efficiency at 120 uA. 

I will get back to you once I got the data.

Thank you,

Regards,

Moheddin.

I see. 

Once you have the data let us know.  Thanks, Moheddin.

Hello Asael,

Please find the efficiency measurements attached within a range of 100 uA to 100 mA. 

Test conditions: Vin = 4.2 V, Vout = 3.3 V, Temp = 25 °C.

Test performed using TPS62086EVM (User's Guide for TPS62085EVM_169 (ti.com))

Thank you,

Regards,

Moheddin.

Thanks for that :D.

Could you help us testing at 3.35V and 3.4V at same currents? Let me know if this is possible.

Regards, Asael.

Hello Asael,

Please find the efficiency measurements attached within a range of 100 uA to 100 mA. 

Test conditions: Vin = 3.35 to 3.4 V, Vout = 3.3 V, Temp = 25 °C.

Test performed using TPS62086EVM (User's Guide for TPS62085EVM_169 (ti.com))

It seems that device enter into 100% duty cycle mode with you operating conditions at some point.

Please find more about 100% duty cycle mode here (Understanding 100% mode in low-power DC/DC converters (ti.com))

If you don't have any further questions, please close the threat by clicking on Resolved.

Thank you,

Regards,

Moheddin.

Thanks for the info Moheddin.

Another question, to understand the current consumption that we should get when the device is on 100% duty cycle, we know that the high-side MOSFET is always on and the low side MOSFET is always off, is the RDS (on) the only element that we have need to consider for calculating the current consumption?