TS612 ST Microelectronics, Inc., TS612 Datasheet - Page 9

• Manufacturer Part Number: TS612
• Description: Dual Wideband Op-amp With High Output Current
• Manufacturer: ST Microelectronics, Inc.

Figure 5 : Equivalent schematic. Ro is the
synthesized impedance
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:
After choosing the k factor, Rs will equal to
1/2RL(k-1).
A good impedance matching assumes:
From (4) and (5) it becomes:
By fixing an arbitrary value for R2, (6) gives:
Finally, the values of R2 and R3 allow us to extract
R1 from (1), and it comes:
with GL the required gain.
CAPABILITIES
The table below shows the calculated compo-
nents
R2=1000
displays the maximum amplitude level on the line
regarding the TS612 maximum output capabilities
(18Vpp diff.) and a 1:2 line transformer ratio.
GL (gain for the
loaded system)
R2 (=R4)
R3 (=R5)
R1
Rs
Vi.Gi
for different values of k. In this case
R1
and the gain=16dB. The last column
=
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)
--------------------------------------------------------- 7
2 1
R2
------ -
R3
Ro
Ro
R o
R3
–
=
=
R2
------ -
R3
=
=
1
---------------------------
RL
1
-- - RL 5
2
2R2
–
-------------------
1
kVoRL
Iout
GL 1
+
2Rs
--------- - 6
–
RL
R2
2Rs1
2Rs
--------- -
,
RL
–
,
–
R2
------ -
R3
,
1/2
RL
POWER CONSUMPTION IN COMMUNICATION
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)
Power Supply: 12V
The TS612 power consumption during emission
on 900 and 4550 meter twisted pair telephone
lines: 450mW
1.3
1.4
1.5
1.6
1.7
k
Passive matching
Active matching
820
490
360
270
240
( )
R1
1500
1600
2200
2400
3300
( )
R3
( )
3.9
5.1
6.2
7.5
9.1
Rs
TS612 Output
Level to get
12.4Vpp on
(Vpp diff)
the line
10.5
12.4
8.7
9.3
9.9
8
Maximum
Line level
(Vpp diff)
TS612
27.5
25.7
25.3
23.7
22.3
18
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