March 2008

PCS3P73U00A

rev 0.2

USB 2.0 Peak EMI reduction IC

5 of 13

Notice: The information in this document is subject to change without notice.

Fig1:

Typical Crystal Interface Circuit

Note: For AC Coupled Interface refer to Application Brief:CT100801

Typical Crystal Specifications

Fundamental AT cut parallel resonant crystal

Nominal frequency

48MHz

Frequency tolerance

± 50 ppm or better at 25°C

Operating temperature range

-25°C to +85°C

Storage temperature

-40°C to +85°C

Load capacitance

18pF

Shunt capacitance

7pF maximum

ESR

25

Ω

USB2.0 signaling rate (frequency) deviation to 1000ppm

peak-to-peak (+/-500ppm). It causes a -4dB peak power

EMI reduction at the 480MHz fundamental USB2.0

frequency. Higher harmonics are reduced more.

compliance limit, it will set the USB2.0 signaling rate

(frequency) deviation to above 1000ppm peak-to-peak.

For settings above 1000ppm the USB2.0 compliance

pass/fail

becomes

gradually

intermittent.

USB2.0

functionality is maintained upto 3000ppm peak-to-peak

signaling rate (frequency) deviation. The EMI tradeoff in

the system is attenuation/compliance. While fully

functional (and compliant intermittent) the 2000ppm

frequency deviation can provide -7dB of EMI attenuation

at the 480MHz fundamental.

R1 = 510Ω

C1 = 27 pF

C2 = 27 pF

Crystal

R