TPS65911: V5IN

Brian Forster

Part Number: TPS65911

I am designing an application that will run off a car battery. In the event the car battery voltage is removed my system will run off an emergency battery just long enough to shut down gracefully. I noticed that when I unplugged incoming voltage that the VDDCTRL died as well. After looking at the datasheet I see that V5IN must have more than 4.5V on it. This means that I will not be able to run this off a single cell 4.2V LiPO battery.

Is there a way to run VDDCTRL down to 3.5V or am I going to have to design in a boost regulator?

over 6 years ago

0 Kevin LaRosa over 6 years ago

TI__Genius 17380 points

Hi Brian,

Thank you for your post. I've assigned it to our expert who should get back to you shortly.

In the meantime, would you be able to potentially add some capacitance to the V5IN net to keep it high long enough for the graceful shutdown? Looking at the UVLO section for V5IN, it looks like 4.1V is the max shutdown voltage so you could potentially just keep it above there for long enough?

0 Brian Forster over 6 years ago in reply to Kevin LaRosa

Intellectual 380 points

Hello Kevin,

That would not be an option. It will take 40 seconds max to gracefully shutdown. 4.2V LiPo batteries go to 3.8V almost instantly but stay there for quite some time with 3.6V being the cuttoff. I need the PMIC to be able to at least run on 3.5V.

Thank you,

0 Nastasha over 6 years ago in reply to Brian Forster

TI__Genius 10000 points

Brian,

As per datasheet suggests, the V5IN rail does need 4.5 volts. Thus, you may need a boost if you plan to use the 4.2 LiPO battery.

Thanks,
Nastasha

0 Brian Forster over 6 years ago in reply to Nastasha

Intellectual 380 points

Nastasha,

That is what I was figuring but was hoping against. Seems silly to need 4.5V to make 1.35V though.

Thank you for your answer.

Power management

Power management forum

TPS65911: V5IN