Datasheet

DS26303: 3.3V, T1/E1/J1, Short-Haul, Octal Line Interface Unit
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6.3.2 LIU Transmit Front-End
It is recommended to configure the transmitter’s LIU as described in Figure 6-4 and in Table 6-4. No series
resistors are required. The transmitter has internal termination for E1, J1, and T1 modes.
Figure 6-4. LIU Front-End
C1
DS26303
(One Channel)
TTIP
TRING
RTIP
RRING
Dt
Dt
Dt
Dt
Ct
1:2
TFt
1:2
TFr
Tx Line
Rx Line
TVDDn
TVSSn
TVS1
3.3V
C2
3.3V
C3
AVDDn
AVSSn
3.3V
C4
Rt
C5
Rt
30 A110 A100 A75
Table 6-4. LIU Front-End Values
MODE COMPONENT
75Ω COAX
120Ω TWISTED
PAIR
100Ω/110Ω
TWISTED PAIR
Tx Capacitance Ct 560pF typical. Adjust for board parasitics for optimal return loss.
Tx Protection Dt
International Rectifier: 11DQ04 or 10BQ060
Motorola: MBR0540T1
Rx Transformer 1:2 TFr
Tx Transformer 1:2 TFt
Pulse: T1124 (0°C to +70°C)
Pulse: T1114 (-40°C to +85°C)
Tx Decoupling (ATVDD) C1
Common decoupling for all eight channels is 68μF.
Tx Decoupling (ATVDD) C2
Recommended decoupling per channel is 0.1μF.
Rx Decoupling (AVDDn) C3
Common decoupling for all eight channels is 68μF.
Rx Decoupling (AVDDn) C4
Common decoupling for all eight channels is 0.1μF.
Rx Termination C5
When in external impedance mode, Rx capacitance for all eight
channels is 0.1μF. Do not populate if using internal impedance
mode.
Rx Termination Rt
When in external impedance mode, the two resistors for all modes
are 15.0Ω ±1%. Do not populate if using internal impedance mode.
Voltage Protection TVS1 SGS-Thomson: SMLVT 3V3 (3.3V transient suppressor)