82P2281PFG IDT, Integrated Device Technology Inc, 82P2281PFG Datasheet - Page 24

• Manufacturer Part Number: 82P2281PFG
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of 82P2281PFG

• Number Of Transceivers: 1
• Screening Level: Industrial
• Mounting: Surface Mount
• Package Type: TQFP
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Lead Free Status / RoHS Status: Compliant

IDT82P2281
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. Table 3 lists the recommended matching resistor values for the
receiver.
3.2.1
Intrusive Monitoring per T1.102 can be performed between two devices.
The monitored link of one device is in normal operation, and the moni-
toring link of the other device taps the monitored one through a high
impedance bridging circuit. Refer to
and
RRING of the monitoring link is dramatically attenuated. To compensate
this bridge resistive attenuation, Monitor Gain can be used to boost the
signal by 22 dB, as selected by the MG[1:0] bits (b1~0, T1/J1-02AH).
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.
Partially Internal Impedance Matching mode. Here the external r or
internal IM is used for voltage division, not for impedance matching. That
is, the r (IM) and the R make up of a resistance bridge. The resistive
Functional Description
In both T1/J1 and E1 short haul applications, the Protected Non-
After the high resistance bridging circuit, the signal arriving at RTIP/
The monitoring link can be configured to any of the External or
Figure 5&Figure 6
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
LINE MONITOR
RECEIVER IMPEDANCE MATCHING
(COAX).
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
Figure 3&Figure 4
•
•
Cp
Figure 2. Receive / Transmit Line Circuit
R
R
•
•
R
R
T
T
D6
D5
VDDAR
(Twisted Pair)
·
VDDAX
VDDAR
VDDAX
D2
D1
D8
D7
D4
D3
·
·
·
International Rectifier - 11DQ04 or 10BQ060
RTIP
RRING
TTIP
TRING
24
SINGLE T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
attenuation of this bridge is 20lg(r/(2R+r)) dB for Twisted Pair or 20lg(r/
(R+r)) dB for COAX. The value of resistive attenuation should be consis-
tent with the setting of Monitor Gain (22 dB).
outputs on the REFA_OUT pin. When set to 0, the output is MCLK;
when set to 1, the output is high level.
Table 3: Impedance Matching Value For The Receiver
Configuration
In case of LOS, REFH_LOS bit (b0, T1/J1-03EH) determines the
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
1
3.3 V
1
R_TERM[2:0]
External Termination
1 X X
August 20, 2009
120 Ω
100 Ω
110 Ω
75 Ω
R
R