TSH112 STMicroelectronics, TSH112 Datasheet - Page 15

• Manufacturer Part Number: TSH112
• Description: WIDE BAND, LOW NOISE OPERATIONAL AMPLIFIERS
• Manufacturer: STMicroelectronics

The amplifier must be biased with a mid supply
(nominaly +Vcc/2), in order to maintain the DC
component of the signal at this value. Several op-
tions are possible to provide this bias supply (such
as a virtual ground using an operational amplifier),
or a two-resistance divider which is the cheapest
solution. A high resistance value is required to lim-
it the current consumption. On the other hand, the
current must be high enough to bias the non-in-
verting input of the amplifier. If we consider this
bias current (5 A) as the 1% of the current
through the resistance divider (500 A) to keep a
stable mid supply, two 5k
used.
The input provides a high pass filter with a break
frequency below 10Hz which is necessary to re-
move the original 0 volt DC component of the input
signal, and to hold it at 2.5V.
Video Multiplexing using the TSH113
(fig.35):
ple TSH113.
ENABLE1
ENABLE1
ENABLE2
ENABLE2
ENABLE3
ENABLE3
IN1
IN1
IN2
IN2
IN3
IN3
R
R
680
680
R
R
680
680
R
R
680
680
G
G
G
G
G
G
Circuit for switching 3 video signals with the tri-
+
+
+
+
+
+
_
_
_
_
_
_
R
R
R
R
R
R
C
C
TSH113
TSH113
TSH113
TSH113
C
C
TSH113
TSH113
C
C
fb,
fb,
fb,
fb,
fb,
fb,
fb,
fb,
fb,
fb,
fb,
fb,
680
680
680
680
680
680
2pF
2pF
2pF
2pF
2pF
2pF
resistances can be
75
75
cable
cable
75
75
Common
Common
OUT
OUT
75
75
TSH110-TSH111-TSH112-TSH113-TSH114
Assuming a low level active onto the disable pins
(1,2,3) as described on page 7 of the datasheet,
any operator can be disable/enable independent-
ly. The two disabled operators will be in standby
mode featuring a high ouput impedance with a
high input/output isolation and a low quiescent
current.
(fig.36):
(fig.37):
Typical output response in standby mode on/off
Typical output response in standby mode off/on
-2.4V
-2.4V
+2.4V
+2.4V
Enabled
Enabled
Output
Output
Standby
Standby
Signal
Signal
Standby
Standby
Signal
Signal
Disabled
Disabled
Output
Output
-2.4V
-2.4V
100ns /div.
100ns /div.
Enabled
Enabled
Output
Output
Disabled
Disabled
Output
Output
10µs /div.
10µs /div.
+2.4V
+2.4V
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