XRT83L30_06 Datasheet, PDF (15/78 Pages) Exar Corporation – SINGLE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR

XRT83L30
REV. 1.0.1 SINGLE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR
TERMINATIONS
SIGNAL NAME
TERSEL1
TERSEL0
PIN #
43
42
TYPE
I
DESCRIPTION
Termination Impedance Select pin 1
Termination Impedance Select pin 0
In the Hardware mode and in the Internal Termination mode (TXTSEL=”1”
and/or RXTSEL=”1”) TERSEL[1:0] control the transmit and receive termina-
tion impedance according to the following table:
TERSEL1 TERSEL0
0
0
0
1
1
0
1
1
Termination
100Ω
110Ω
75 Ω
120Ω
RXRES1
RXRES0
In the Internal Termination mode, the receive termination is realized com-
pletely by internal resistors or the combination of internal and one fixed exter-
nal resistor (see description for RXRES[1:0] pins). In the internal termination
mode the transformer ratio of 1:2 and 2:1 is required for the transmitter and
receiver respectively with the transmitter output AC coupled to the trans-
former.
NOTE: This pin is internally pulled "Low" with a 50kΩ resistor.
51
I
Receive External Resistor Control pin 1
52
Receive External Resistor Control pin 0
In Hardware mode, RXRES[1:0] pins selects the required value of the exter-
nal fixed resistor for the receiver according to the following table. This mode
is only available in the internal impedance mode by pulling RXTSEL “High”.
RXRES1 RXRES0
RX Fixed Resistor
0
0
No External Fixed Resistor
0
1
240Ω
1
0
210Ω
1
1
150Ω
NOTE: Internally pulled “Low” with 50kΩ resistor.
12