my application is to do a power off function with DA14681 Power Manager and DA14681 is main controller. I plan to use the CCCV charger function of DA14681 to charge my rechargeable battery, so I have to connect the Vbat1, Vbat2 and "rechargeable battery" together. That means I can not power down the DA14681 by adding a power switch between "rechargeable battery" and "Vbat1, Vbat2", is it correct ? if the answer is YES, is it possible to design a power off mechanism If I can not add any power switch between "rechargeable battery" and "Vabt1, Vbat2" ?
Device:
Hi nigelyang,
The DA14681 cannot self-power off while the VBAT is connected. Power-off can be achieved by cutting-off the VBAT and not having the VBUS (USB) connected. As you can understand in this state there is no way to use the DA14681 to turn-on itself. You will need external circuitry to be able to connect/disconnect the VBAT (controlled also by external circuitry) and also this additional circuitry must not any additional resistance in series to the VBAT power supply to avoid voltage drops when the DA14681 is active.
The lowest power mode you can have the 681 and be able to wakeup by itself, without complex additional circuitry is the Hibernation. This is the clockless sleep and the power consumption of the VBAT is a couple of uA (about 1.3-1.6uA).
If this is not covering your project requirements, then the additional external circuit is inevitable. The simplest approach to implement power-OFF functionality it to use a p-FET which will be controlled by a GPIO and a button. To turn-on you system you need to keep pressed long enough so the DA14680 will boot and be able to drive the GPIO. When you want to power-off then stop driving the GPIO and the p-FET will cut the VBAT. This though, might cause problems with charging where the current flows at the opposite direction and the p-FET will block it.
我们的建议是use the Hibernation mode. It is the simplest approach and the power budget is very low.
Thanks, PM_Dialog