TS613ID Просмотр технического описания (PDF) - STMicroelectronics
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TS613ID Datasheet PDF : 10 Pages
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TS613
By identification of both equations (2) and (3), the
synthesized impedance is, with Rs1=Rs2=Rs:
Ro
=
------R----s------
1
–
R-----2-
R3
,( 4 )
Figure 5 : Equivalent schematic. Ro is the syn-
thesized impedance
Ro
Iout
Vi.Gi
1/2RL
Unlike the level Vo° required for a passive imped-
ance, Vo° will be smaller than 2Vo in our case. Let
us write Vo°=kVo with k the matching factor vary-
ing between 1 and 2. Assuming that the current
through R3 is negligeable, it comes the following
resistance divider:
Ro
=
-----k---V-----o---R----L-------
RL + 2Rs1
After choosing the k factor, Rs will equal to
1/2RL(k-1).
A good impedance matching assumes:
R o = -12- RL,(5)
From (4) and (5) it becomes:
R-----2-
R3
=
1
–
-2---R----s-
RL
,(6
)
By fixing an arbitrary value for R2, (6) gives:
R3
=
-------R----2--------
1
–
-2---R----s-
RL
Finally, the values of R2 and R3 allow us to extract
R1 from (1), and it comes:
R1 = ------------------------2----R----2-------------------------,(7)
2 1
–
RR-----23-
GL
–
1
–
R-----2-
R3
with GL the required gain.
GL (gain for the
loaded system)
R1
R2 (=R4)
R3 (=R5)
Rs
GL is fixed for the application requirements
GL=Vo/Vi=0.5(1+2R2/R1+R2/R3)/(1-R2/R3)
2R2/[2(1-R2/R3)GL-1-R2/R3]
Abritrary fixed
R2/(1-Rs/0.5RL)
0.5RL(k-1)
CAPABILITIES
The table below shows the calculated compo-
nents for different values of k. In this case
R2=1000Ω and the gain=16dB. The last column
displays the maximum amplitude level on the line
regarding the TS613 maximum output capabilities
(18Vpp diff.) and a 1:2 line transformer ratio.
Active matching
k
R1 R3 Rs
(Ω) (Ω) (Ω)
1.3 820 1500 3.9
1.4 490 1600 5.1
1.5 360 2200 6.2
1.6 270 2400 7.5
1.7 240 3300 9.1
Passive matching
TS613 Output
Level to get
12.4Vpp on
the line
(Vpp diff)
8
8.7
9.3
9.9
10.5
12.4
Maximum
Line level
(Vpp diff)
27.5
25.7
25.3
23.7
22.3
18
MEASUREMENT OF THE POWER
CONSUMPTION IN THE ADSL APPLICATION
Conditions:
Passive impedance matching
Transformer turns ratio: 2
Power Supply: 12V
Maximun level required on the line: 12.4Vpp
Maximum output level of the driver: 12.4Vpp
Crest factor: 5.3 (Vp/Vrms)
The TS613 power consumption during emission
on 900 and 4550 meter twisted pair telephone
lines: 360mW
8/10
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