TCM series
1005,1210,1608, 2010 type
TDK CORPORATION
10
TCM
Transmission signal waveform
With TCM1005-900-2P
USB2.0
Controller
IC
USB2.0
Controller
IC
USB Cable (0.5m)
TP2
TP3
TCM1005-900-2P
Applied templates
Transmission waveform observation point
HUB
DEVICE
DATA
Transmission signal waveform
Without EMI preventive components
Eye-pattern diagram
TP2 template
for 0.5m Cable
0.1
0.2
0
-0.2
-0.1
-0.4
-0.3
-0.5
0.5
0.3
0.4
0
0.4
0.8
1.2
1.6
2.0
Time (ns)
D
+
,D
-
(V)
Eye-pattern diagram
TP2 template
for 0.5m Cable
0.1
0.2
0
-0.2
-0.1
-0.4
-0.3
-0.5
0.5
0.3
0.4
0
0.4
0.8
1.2
1.6
2.0
Time (ns)
D
+
,D
-
(V)
Impedance Analyzer E4991A (Agilent Technologies)
TCM1005-900-2P
Frequency characteristics
Frequency (MHz)
1
10
100
1000
10000
1000
100
10
1
Characteristic
impedance
(
)
1
10
100
1000 3000
10000
1000
100
10
1
Impedance
(
)
Frequency (MHz)
Differential-mode
Impedance
Common-mode
Impedance
Measurement condition
Favorable transmission waveforms are achieved with
appropriate CMF(common-mode filter) character-
istic impedance* and low differential-mode imped-
ance.
Measurement results
For operational test, the same EMI countermeasure
components are implemented on both the signal
sending and receiving sides, assuming actual use
conditions.
The measurement data below are the results of ob-
servation at a point near TP3 using 0.5m cables. To
observe the characteristic superiority of TCM, the TP2
template, which is more severe than TP3, was used.
Actual measurement example of
USB2.0 differential signal waveform
TCM1005
At the USB2.0's data transmission speed (High speed)
of 480Mbps, repetitive pulse frequency is 240Mhz,
which requires sufficient consideration for effects on
the signal waveform when selecting EMI counter-
measure components to deter the radiation noise
from the cables, etc.
The USB2.0 transmission signal waveforms where no
EMI countermeasure components are attached,
and where TCM1005-900-2P is attached near the
connectors for both HUB and DEVICE are as follows:
*CMF(common-mode filter) characteristic impedance:
With the USB2.0 standard, the required characteristic impedance
of a common-mode filter is 90
.