DragonBoard BATTERY (J14) as VPH_PWR SOURCE


#1

Hello.
Is it possible to power DragonBoard using Li-Po or Li-Ion battery through J14?
Regarding schematic VPH_PWR SOURCE can be switched to VBATT_CONN using this configuration:

DNI R108
INSTALL J14, R136
DNI R134,R135
DNI R106,R88
INSTALL R130

Almost all components location can be easily found on PCB (except R106).
Does anyone know where is R106 on PCB?

Thanks!


#2

Hi Ihor

At a high level the changes you are making are required to power the board from a 3.7V battery, however after you make the changes you will run into a host of other problems.

  1. There will be no 5V supply on the board, hence the HDMI output, and the USB ports will not work, also any mezzanine cards that require 5V will not work. This might be acceptable depending on your use case.
  2. The charger in the PMIC needs to be programmed to charge the battery you have attached, and measure the battery temperature with a thermistor in the battery pack. The charge rates need to be tuned to the specific battery chemistry, temperature, and capacity that you are using. These rates are not reprogrammable in the open source SW. Hence you may cause your battery to over charge, or charge too fast causing a fire. This is one of the reasons we elected to not support 3.7V batteries. (the other reason being the added cost of a 3.7V to 5V boost circuit that the majority of users would never need).

The ‘correct’ solution to running the 410c on batteries is to use an external battery pack and charger. You can use a 7.2V (or 9.6V, 11.1V, 12V, or 14.4v) battery pack since the 410c will operate as low as 6.5V. You don’t need to connect the battery pack to the barrel connector, you can connect it directly to the Low-speed connector.

Full Disclosure: I am an employee of Qualcomm Canada, any opinions I may have expressed in this or any other post may not reflect the opinions of my employer.


#3

Hi,

I want to use also a battery, as you said with 3.7V, HDMI, USB, mezzanine would not work.

The PMIC 8916 on the dragon board has Switched-mode power supplies, four buck converters, and one 5V boost converter.
On the datasheet of the PMIC 8916 page 50, Table 3-21 Boost specifications, they share that the boost output is 5V for 3.7V input.
I didn’t find any information where I can pick up this 5V boost output, or is it not connected to anything on the dragon board?

One other question would be, smartphones which are using the 410c, do they not have 3.7V batteries?


#4

Hi,

I want to use also a battery, as you said with 3.7V, HDMI, USB, mezzanine would not work.

The PMIC 8916 on the dragon board has Switched-mode power supplies, four buck converters, and one 5V boost converter.
On the datasheet of the PMIC 8916 page 50, Table 3-21 Boost specifications, they share that the boost output is 5V for 3.7V input.
I didn’t find any information where I can pick up this 5V boost output, or is it not connected to anything on the dragon board?

One other question would be, smartphones which are using the 410c, do they not have 3.7V batteries?

Yes, phones have 3.7V batteries. The constraints here do not from from
the underlying 410E chipset, they are part of the design of the power
circuits on the board. The board must deliver a level of power to
peripherals that a phone is not required to achieve (because it doesn’t
have the requires sockets and connectors). I suspect this is why the
board disregards the PMIC 5V boost output and provides its own instead.