Datasheet
DS26303: 3.3V, T1/E1/J1, Short-Haul, Octal Line Interface Unit
35 of 101
Register Name:
TST
Register Description:
Template Select Transceiver Register
Register Address:
10h
Bit # 7 6 5 4 3 2 1 0
Name — — — — — TST2 TST1 TST0
Default 0 0 0 0 0 0 0 0
Bits 2 to 0: TST Template Select Transceiver [2:0] (TST [2:0]). TST[2:0] is used to select the transceiver that the
transmit template select register (hex 11) applies to. See
Table 5-10.
Table 5-10. TST Template Select Transceiver Register
TST[2:0] CHANNEL TST[2:0] CHANNEL
000 1 100 5
001 2 101 6
010 3 110 7
011 4 111 8
Register Name:
TS
Register Description:
Template Select Register
Register Address:
11h
Bit # 7 6 5 4 3 2 1 0
Name RIMPOFF TIMPOFF — — TIMPRM TS2 TS1 TS0
Default 0 0 — — 0 0 0 0
Bit 7: Receive Impedance Match Off (RIMPOFF). If this bit is set, all the receive impedance match is turned off.
Bit 6: Transmit Impedance Termination Off (TIMPOFF). If this bit is set, all the internal transmit terminating
impedance is turned off.
Bit 3: Transmit Impedance Receive Match (TIMPRM). This bit selects the internal transmit termination
impedance and receive impedance match for E1 mode and T1/J1 mode. Note: If the part number ends with –120,
then the default is 120Ω and 75Ω when set for El mode only.
DEVICE BIT SETTING
E1 MODE (Ω) T1 MODE (Ω)
DS26303L-120 0 120 100
DS26303L-120 1 75 110
DS26303L-75 0 75 100
DS26303L-75 1 120 110
Bits 2 to 0: Template Selection [2:0] (TS[2:0]). Bits TS[2:0] are used to select E1 or T1/J1 mode, the template,
and the settings for various cable lengths. The impedance termination for the transmitter and impedance match for
the receiver are specified by bit TIMPRM. See
Table 5-11 for bit selection of TS[2:0].
Table 5-11. Template Selection
TS[2:0] LINE LENGTH
CABLE LOSS
(dB)
IMPEDANCE (Ω)
1
OPERATION MODE
011 0–133ft. ABAM 0.6 100/110 T1/J1
100 133–266ft. ABAM 1.2 100/110 T1
101 266–399ft. ABAM 1.8 100/110 T1
110 399–533ft. ABAM 2.4 100/110 T1
111 533–655ft. ABAM 3.0 100/110 T1
000 G.703 coaxial and twisted pair cable 75/120 E1
001 and 010 Reserved — — —
1
See TIMPRM bit in SWM or TIMPRM pin in HWM for transmit impedance and receive match selection.