LT1229 Linear Technology, LT1229 Datasheet - Page 9

• Manufacturer Part Number: LT1229
• Description: Dual and Quad 100MHz Current Feedback Amplifiers
• Manufacturer: Linear Technology

A
Assumptions:
Maximum Supply Voltage for 75 Cable Driving Applications at
Maximum Ambient Temperature
PART
LT1229MJ8
LT1229CJ8
LT1229CN8
LT1229CS8
LT1230MJ
LT1230CJ
LT1230CN
LT1230CS
Slew Rate
The slew rate of a current feedback amplifier is not
independent of the amplifier gain the way it is in a tradi-
tional op amp. This is because the input stage and the
output stage both have slew rate limitations. The input
stage of the LT1229/LT1230 amplifiers slew at about
100V/ s before they become nonlinear. Faster input sig-
nals will turn on the normally reverse-biased emitters on
the input transistors and enhance the slew rate signifi-
cantly. This enhanced slew rate can be as much as
2500V/ s.
The output slew rate is set by the value of the feedback
resistors and the internal capacitance. At a gain of ten with
a 1k feedback resistor and 15V supplies, the output slew
rate is typically 700V/ s and – 1000V/ s. There
is no input stage enhancement because of the high gain.
PPLICATI
1. The maximum ambient is 70 C for the commercial
2. The load is a double-terminated video cable, 150 .
3. The maximum output voltage is 2V (peak or DC).
4. The thermal resistance of each package:
parts (C suffix) and 125 C for the full temperature
parts (M suffix).
J8 is 100 C/W
N8 is 100 C/W
S8 is 150 C/W
PACKAGE
Plastic DIP
Plastic SO8
Ceramic DIP
Ceramic DIP
Plastic DIP
Plastic SO14
Ceramic DIP
Ceramic DIP
O
U
S
I FOR ATIO
U
MAX POWER AT T
0.500W @ 125 C
1.050W @ 70 C
0.800W @ 70 C
0.533W @ 70 C
0.625W @ 125 C
1.313W @ 70 C
1.143W @ 70 C
0.727W @ 70 C
J is 80 /W
N is 70 /W
S is 110 /W
W
A
MAX SUPPLY
V
V
V
V
V
V
V
V
S
S
S
S
S
S
S
S
U
< 10.1
< 18.0
< 15.6
< 10.6
< 6.6
< 13.0
< 11.4
< 7.6
Larger feedback resistors will reduce the slew rate as will
lower supply voltages, similar to the way the bandwidth is
reduced.
Settling Time
The characteristic curves show that the LT1229/LT1230
amplifiers settle to within 10mV of final value in 40ns to
55ns for any output step up to 10V. The curve of settling
to 1mV of final value shows that there is a slower thermal
contribution up to 20 s. The thermal settling component
comes from the output and the input stage. The output
contributes just under 1mV per volt of output change and
the input contributes 300 V per volt of input change.
Fortunately, the input thermal tends to cancel the output
thermal. For this reason the noninverting gain of two
configurations settles faster than the inverting gain of one.
Large-Signal Response, A
Large-Signal Response, A
V
= 10, R
V
= 2, R
LT1229/LT1230
F
F
= 1k, R
= R
G
= 750
G
LT1229 • TA07
= 110
LT1229 • TA08
9