78Q2123/78Q2133 Data Sheet DS_21x3_001
30 Rev. 1.6
4.7 Analog Electrical Characteristics
4.7.1 100BASE-TX Transmitter
Parameter Condition Min Nom Max Unit
Peak Output Amplitude
(|Vp+|, |Vp-|)
(see note below)
Best-fit over 14 bit times;
0.4 dB Transformer loss
950 1050 mVpk
Output Amplitude
Symmetry
|Vp -|
|Vp +| 0.98 1.02
Output Overshoot
Percent of Vp+, Vp-
5 %
Rise/Fall time (tr, tf)
10-90% of Vp+, Vp-
3 5 ns
Rise/Fall time Imbalance
|tr - tf|
500 ps
Duty Cycle Distortion Deviation from best-fit time-
grid;
010101... Sequence
±250
ps
Jitter Scrambled Idle
1.4 ns
Note: Measured at the line side of the transformer.
Test Condition: Transformer P/N: TLA-6T103
Line Termination: 100 Ω ±1%
4.7.2 100BASE-TX Transmitter (Informative)
The specifications in the following table are included for information only. They are mainly a function of
the external transformer and termination resistors used for measurements.
Parameter Condition Min Max Unit
Return Loss 2 < f < 30 MHz
30 < f < 60 MHz
60 < f < 80 MHz
16
16 20
30
−
log
f
MHz
10
dB
Open-Circuit Inductance -8 < Iin < 8 mA 350
µH
4.7.3 100BASE-TX Receiver
Parameter Condition Min Nom Max Unit
Signal Detect Assertion
Threshold
500 600 700 mVppd
Signal Detect De-assertion
Threshold
275 350 425 mVppd
Differential Input Resistance 20
kΩ
Jitter Tolerance (pk-pk) Not tested in production 4 ns
Baseline Wander Tracking -75 +75 %
Signal Detect Assertion Time Not tested 1000
µs
Signal Detect De-assertion
Time
Not tested 4
µs
