Datasheet

7
LT1457
APPLICATIONS INFORMATION
WUU
U
High Speed Operation
When the feedback around the op amp is resisitive (R
F
), a
pole will be created with R
F
, the source resistance and
capacitance (R
S
, C
S
), and the amplifier input capacitance
(C
IN
≈ 4pF). In low closed loop gain configurations and
with R
S
and R
F
in the kilohm range, this pole can create
excess phase shift and even oscillation on high speed
amplifiers. Because the LT1457’s phase margin is very
high, this problem is minimal. However, a small capacitor
(C
F
) in parallel with R
F
eliminates this problem. With R
S
(C
S
+ C
IN
) = R
F
C
F
, the effect of the feedback pole is completely
removed.
–
+
LT1457 AI04
R
S
R
F
C
F
C
S
C
IN
OUTPUT
Dimension in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
U
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1
2
3
4
0.150 – 0.157
(3.810 – 3.988)
8
7
6
5
0.189 – 0.197
(4.801 – 5.004)
0.228 – 0.244
(5.791 – 6.197)
0.010 – 0.020
(0.254 – 0.508)
0.016 – 0.050
0.406 – 1.270
× 45°
0°– 8° TYP
0.008 – 0.010
(0.203 – 0.254)
SO8 0392
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
S8 Package
8-Lead Plastic SOIC
N8 Package
8-Lead Plastic DIP
N8 0392
0.045 ± 0.015
(1.143 ± 0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.065
(1.651)
TYP
0.045 – 0.065
(1.143 – 1.651)
0.130 ± 0.005
(3.302 ± 0.127)
0.020
(0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.125
(3.175)
MIN

12
3
4
876
5
0.250 ± 0.010
(6.350 ± 0.254)


0.400
(10.160)
MAX
0.009 – 0.015
(0.229 – 0.381)
0.300 – 0.320
(7.620 – 8.128)
0.325
+0.025
–0.015
+0.635
–0.381
8.255
()