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UMTS/HSPA Module Series

UC20 Hardware Design

UC20_Hardware_Design Confidential / Released 44 / 82

 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.

 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 25: 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

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