XRT83L30 Datasheet, PDF (30/78 Pages) Exar Corporation – SINGLE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR

XRT83L30
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ONE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR
REV. P1.3.0
PRELIMINARY
TRANSMIT AND RECEIVE TERMINATIONS
The XRT83L30 is a versatile LIU that can be programmed to use one Bill of Materials (BOM) for worldwide
applications for T1, J1 and E1. For specific applications the internal terminations can be disabled to allow the
use of existing components and/or designs.
RECEIVER
INTERNAL RECEIVE TERMINATION MODE
In Hardware mode, RXTSEL (Pin 44) can be tied “High” to select internal termination mode or tied “Low” to
select external termination mode. By default the XRT83L30 is set for external termination mode at power up or
at Hardware reset.
TABLE 6: RECEIVE TERMINATION CONTROL
RXTSEL
RX TERMINATION
0
EXTERNAL
1
INTERNAL
In Host mode, bit 7 in the appropriate register, (Table 20, “Microprocessor Register #1, Bit Description,” on
page 47), is set “High” to select the internal termination mode for the receive channel.
FIGURE 13. SIMPLIFIED DIAGRAM FOR THE INTERNAL RECEIVE AND TRANSMIT TERMINATION MODE
TPOS
TNEG
TCLK
TX
Line Driver
RPOS
RNEG
RCLK
RX
Equalizer
TTIP
1 ^T1 5
R_int
0.68µF
TRING
R_int
RTIP
R_int
RRING
4
8
1:2
5 ^T2 1
8
4
1:1
TTIP
75 Ω, 100 Ω
110 Ω or 120 Ω
TRING
RTIP
75 Ω, 100 Ω
110 Ω or 120 Ω
RRING
If the internal termination mode (RXTSEL = “1”) is selected, the effective impedance for E1, T1 or J1 can be
achieved either with an internal resistor or a combination of internal and external resistors as shown in Table 7.
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