Using the AT89RFD-08 Board
2-20
AT89RFD-08 Hardware User Guide
4382E–MP3–05/06
2.10.2
USB
The UVDD line must be large enough to drive 500mA.
The D+ and D- lines must be routed side by side because they are a differential pair.
There must be two UVSS lines on each side of this two lines.
USB serial resistors 27 ohms on D+ and D- lines must be placed as close as possible of
the processor.
2.10.3
Audio
Resistance on the power supply lines and audio lines should be lower than 100 mOhms,
especially for:
n Headset Output (Audio Channel Headset Driver Output HSL and HSR).
n Power Amplifier Output. HPP and HPN signals must be routed side by side because
they are a differential pair.