RK3288 Hardware Design Guide
32.768KHz Crystal should be surrounded by GND, take the second layer as reference
ground plane, make sure no other traces will be routed on this plane in case of interference to
clock, as shown in Fig 5-20.
。
Fig 5-20
USB port in RC5T620 need to be shorted to ADP port if USB is used as charger port, to
reduce trace power consumption (when the internal resistor of internal switch tube of USB
charger port is bigger than ADP charger port). (Note: After USB charger port was shorted to
ADP charger port, charge ADP port first, so trace from USB port to ADP port should be wider.)
5.5 PMIC ACT8846
To optimize 1-cell battery solution, it is suggested to use 2-cell battery solution with
ACT8846+BQ24133 as charger IC and CW2013 as Coulomb Counting IC. Although this
solution has slightly higher cost and more power consumption than RC5T620, it has less
requirement for battery, also has better stability and less design demands.
This solution has similar Layout with RC5T620, only need to make sure traces of input,
output and inductors should be wider, input and output capacitors have better connection to
ground, and full vias should be placed under CPU to ensure better thermal dissipation and
good GND connection as shown in Fig 5-21.
Fig 5-21
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