LT1189 LINER [Linear Technology], LT1189 Datasheet - Page 10

• Manufacturer Part Number: LT1189
• Description: Low Power Video Difference Amplifier
• Manufacturer: LINER [Linear Technology]

LT1189
A
10
PPLICATI
A
A
V
V
= 4, R
= 4, R
Closed-Loop Voltage Gain vs Frequency
–10
–20
30
20
10
0
100k
Small-Signal Transient Response
Small-Signal Transient Response
FB
FB
= 910 , R
= 910 , R
V
T
A
R
R
O
S
A
V
FB
G
= 25°C
= ±5V
= 4
= 300
= 900
U
S
G
1M
G
= 300
= 300 , CFB = 5pF
FREQUENCY (Hz)
I FOR ATIO
U
10M
C
C
FB
FB
= 0pF
= 5pF
W
LT1189 • AI06
100M
LT1189 • AI07
LT1189 • AI08
U
Reducing the Closed-Loop Bandwidth
Although it is possible to reduce the closed-loop band-
width by using a feedback zero, instability can occur if the
bandwidth is made too low. An alternate technique is to do
differential filtering at the input of the amplifier. This
technique filters the differential input signal, and the
differential noise, but does not filter common-mode noise.
Common-mode noise is rejected by the LT1189’s CMRR.
Using the Shutdown Feature
The LT1189 has a unique feature that allows the amplifier
to be shutdown for conserving power, or for multiplexing
several amplifiers onto a common cable. The amplifier will
shutdown by taking pin 5 to V
dissipates 15mW while maintaining a true high impedance
output state of about 20k in parallel with the feedback
resistors. For MUX applications, the amplifiers may be
configured inverting, non-inverting, or differential. When
the output is loaded with as little as 1k from the amplifier’s
feedback resistors, the amplifier shuts off in 600ns. This
shutoff can be under the control of HC CMOS operating
between 0V and – 5V.
eN
eN
SIG
CM
D
68pF
110
110
R1
R2
C1
10MHz Bandwidth Limited Amplifier
3
2
1
8
100
REF
FB
+
–
LT1189
–5V
5V
–
7
4
. In shutdown, the amplifier
909
f
A
V
6
–3dB
OUT
V
= 10
=
=
2 (R1 + R2)C1
SIG + eN
FILTER
V
OUT
1
D
+
eN
CMR
LT1189 • AI09
CM