IDT82P2282 Integrated Device Technology, Inc., IDT82P2282 Datasheet - Page 25

• Manufacturer Part Number: IDT82P2282
• Description: 2 Channel T1/J1/E1 Transceiver
• Manufacturer: Integrated Device Technology, Inc.

IDT82P2282
3.2
impedance matching circuit or external impedance matching circuit.
circuit is enabled. 100 Ω, 110 Ω, 75 Ω or 120 Ω internal impedance
matching circuit can be selected by the R_TERM[1:0] bits.
circuit is disabled, and different external resistors should be used to real-
ize different impedance matching.
cable for one link. Table 3 lists the recommended impedance matching
value for the receiver.
receive internal impedance circuitry, the non-intrusive monitoring can be
performed between two devices. The monitored link of one device is in
normal operation, and the monitoring link of the other device taps the
monitored one through a high impedance bridging circuit (refer to
Figure 3 and Figure 4). Because of the high resistance bridging circuit,
the signal arriving at the RTIPn/RRINGn of the monitoring link is dramat-
ically attenuated. To compensate this attenuation, the Monitor Gain can
be used to boost the signal by 22 dB, 26 dB and 32 dB selected by the
MG[1:0] bits. For normal operation, the Monitor Gain should be set to 0
dB, i.e. the Monitor Gain of the monitored link should be 0 dB.
Functional Description
The receiver impedance matching can be realized by using internal
When the R_TERM[2] bit is ‘0’, the internal impedance matching
When the R_TERM[2] bit is ‘1’, the internal impedance matching
Figure 2 shows the appropriate components to connect with the
In short haul applications, after the data stream passes through the
RECEIVER IMPEDANCE MATCHING
R
X
T
Line
X
Line
Note: 1. Common decoupling capacitor
A
B
2. Cp 0-560 (pF)
3. D1 - D8, Motorola - MBR0540T1;
•
•
2:1
1:1
•
•
Cp
R
Figure 2. Receive / Transmit Line Circuit
R
•
•
R
R
T
T
D6
D5
VDDAR
·
VDDAX
VDDAR
VDDAX
D2
D1
D8
D7
D4
D3
·
·
·
International Rectifier - 11DQ04 or 10BQ060
RTIP
RRING
TTIP
TRING
14
Table 3: Impedance Matching Value For The Receiver
DUAL T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
Configuration
120 Ω (E1)
100 Ω (T1)
110 Ω (J1)
75 Ω (E1)
Cable
VDDAR
VDDAX
GNDA
GNDA
R_TERM[2:0]
Internal Termination
0.1µF
0.1µF
0 0 0
0 0 1
0 1 0
0 1 1
•
•
120 Ω
R
R
68µF
68µF
3.3 V
3.3 V
1
1
R_TERM[2:0]
External Termination
1 X X
October 7, 2003
120 Ω
100 Ω
110 Ω
75 Ω
R
R