UMTS/HSPA Module Series
UC20 Hardware Design
UC20_Hardware_Design Confidential / Released 47 / 84
In order to ensure the USB interface design corresponding with the USB 2.0 specification, please comply
with the following principles.
It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential trace is 90ohm.
Do not route signal traces under crystals, oscillators, magnetic devices and RF signal traces. It is
important to route the USB differential traces in inner-layer with ground shielding not only upper and
lower layer but also right and left side.
Pay attention to the influence of junction capacitance of ESD component on USB data lines. Typically,
the capacitance value should be less than 2pF (e.g.ESD9L5.0ST5G).
Keep the ESD components as closer to the USB connector as possible.
UC20 module can only be used as a slave device.
The USB interface is recommended to be reserved for firmware upgrade in your design. The following
figure shows the recommended test points.
Module
USB_DM
USB_DP
VBAT_BB
USB_VBUS
PWRKEY
GND
VBAT_RF
USB_DM
USB_DP
VBAT
USB_VBUS
PWRKEY
GND
Connector
Figure 27: Test Points of Firmware Upgrade
3.13. PCM and I2C Interface
UC20 provides one Pulse Code Modulation (PCM) digital interface for audio design, which supports the
following modes:
Primary mode (short sync, works as both master and slave)
Auxiliary mode (long sync, works as master only)
NOTE