78Q2120-64CG ETC [List of Unclassifed Manufacturers], 78Q2120-64CG Datasheet - Page 29

• Manufacturer Part Number: 78Q2120-64CG
• Description: 10/100BASE-TX Ethernet Transceiver
• Manufacturer: ETC [List of Unclassifed Manufacturers]

ISOLATION TRANSFORMERS
Two simple 1:1 isolation transformers are all that are required at the line interface, but transformers with
integrated common-mode choke are recommended for exceeding FCC requirements.
recommended line transformer characteristics:
Note:
transformer, insertion loss up to 1.3 dB can be compensated by increasing the line drive current by means of
reducing the RIBB resistor value.
REFERENCE CRYSTAL
If the internal crystal oscillator is to be used, a crystal with the following characteristics should be chosen:
Parameters at 25
Temperature Stability ( 0 - 70
Motional Capacitance (min)
Inter-Winding Capacitance
Spurious Response (max)
Shunt Capacitance (max)
Series Resistance (max)
Open-Circuit Inductance
Frequency Tolerance
Leakage Inductance
The 100Base-TX amplitude specifications assume a transformer loss of 0.5 dB.
Load Capacitance
Oscillation Mode
D.C. Resistance
Insertion Loss
Turns Ratio
Frequency
NAME
HIPOT
NAME
Aging
o
C
2
o
C ; Drive Level = 0.5 mW
o
C)
Parallel Resonance, Fundamental Mode
> 5 dB below main within 500 kHz
1 CT : 1 CT
0.40 uH (max)
350 uH (min)
12 pF (max)
0.9
1.1 dB (typ)
1500 Vrms
25.00000
VALUE
VALUE
15
10
25
50
8
2
5
29
(max)
5%
Ethernet Transceiver
@ 10 mV, 10 kHz
10/100BASE-TX
@ 1 MHz (min)
CONDITION
0 - 100 MHz
PPM/yr
UNITS
PPM
PPM
MHz
This table gives the
For the transmit line
pF
pF
fF
78Q2120