5: Carrier Board
Snapdragon 845 HDK Hardware Development Kit User Guide
24
Power Option
The HDK development kit power source connects to the 12V DC power supply jack J0701. Starting from the
power jack, the 12V power supply branches off into different voltage rails via step down converters on the
carrier board and PMIC on the Processor board. The processor board is powered by 3.9V via Silergy step
down converter U0703 on the carrier board.
Figure 5-2 J0701 12V DC Power Jack
The processor board includes three PMIC modules. The functionalities of the three modules are outlined
below.
PM845 and PM8005 core PMICs are used for:
Source various regulated power rails
Source system clock
PMI8998 Interface PMIC is used for:
Source various regulated power rails
Support for battery charging on the PM845 is configurable on the platform. The carrier board uses a 3.9V
constant power input and battery to the processor board. A DIP switch is used to enable/disable charge
function. Make sure turn off battery charging when 12V DC in is used and USB charger is inserted.
Debug Serial UART header J2103
Figure 5-3 J2103 3.3V TTL Debug UART
The header consists of TX, RX and GND pins. It is a 3.3V TTL UART header. To get the serial terminal
working with a PC, the following cable (or similar) is needed
http://www.digikey.ca/product-detail/en/TTL-232R-RPI/768-1204-ND/4382044
