AD8153_15 Datasheet, PDF (21/24 Pages) Analog Devices – Single Buffered Mux/Demux Switch

OUTPUT COMPLIANCE
Figure 40 is a graphical depiction of the single-ended waveform
at the output of the AD8153. The common-mode level (VOCM)
and the amplitude (VOSE) of this waveform are a function of the
output tail current (IT), the output termination supply voltage
(VTTO), the topology of the far-end receiver, and whether ac- or
dc-coupling is used. Keep in mind that the output tail current
varies with the pre-emphasis level. The user must ensure that
the high (VH) and low (VL) voltage excursions at the output are
within the single-ended absolute voltage range limits as
specified in Table 1. Failure to understand the implications of
output signal levels and the choice of ac- or dc-coupling may
lead to transistor saturation and poor transmitter performance.
AD8153
Table 9 shows an example calculation of the output levels for the
typical case, where VCC = VTTO = 3.3 V, with 50 Ω far-end
terminations to a 3.3 V supply.
V_TTO
V_OCM
V_H
V_OSE-DC V_OSE-BOOST
V_L
~320ps
Figure 40. Single-Ended Output Waveform
Table 9. Output Voltage Levels
PE Setting
0
1
2
3
IT (mA)
16
20
24
28
VOSE-DC (mV p-p)
400
400
400
400
VOSE-BOOST (mV p-p)
400
500
600
700
DC-Coupled
VOCM (V) VH (V) VL (V)
3.1
3.3
2.9
3.05
3.3
2.8
3
3.3
2.7
2.95
3.3
2.6
AC-Coupled
VOCM (V) VH (V) VL (V)
2.9
3.1
2.7
2.8
3.05 2.55
2.7
3
2.4
2.6
2.95 2.25
Table 10. Symbol Definitions
Symbol
VOSE-DC
VOSE-BOOST
VOCM (dc-coupled)
VOCM (ac-coupled)
VH
Formula
I_{T PE =0} × 25Ω
I_T × 25Ω
V_TTO
−
I_T
2
× 25Ω
V_TTO
−
I_T
2
× 50Ω
VOCM + VOSE-BOOST/2
VL
VOCM - VOSE-BOOST/2
Definition
Single-ended output voltage swing after settling
Boosted single-ended output voltage swing
Common-mode voltage when the output is dc-coupled
Common-mode voltage when the output is ac-coupled
High single-ended output voltage excursion
Low single-ended output voltage excursion
Rev. 0 | Page 21 of 24