LTC1419AISW Linear Technology, LTC1419AISW Datasheet - Page 10

• Manufacturer Part Number: LTC1419AISW
• Description: IC A/D CONV 14BIT SAMPLNG 28SOIC
• Manufacturer: Linear Technology

Specifications of LTC1419AISW

• Number Of Bits: 14
• Sampling Rate (per Second): 800k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 240mW
• Voltage Supply Source: Dual ±
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
LTC1419
that the amplifier driving the analog input(s) must settle
after the small current spike before the next conversion
starts (settling time must be 200ns for full throughput
rate).
Choosing an Input Amplifier
Choosing an input amplifier is easy if a few requirements
are taken into consideration. First, to limit the magnitude
of the voltage spike seen by the amplifier from charging
the sampling capacitor, choose an amplifier that has a
low output impedance (< 100Ω) at the closed-loop band-
width frequency. For example, if an amplifier is used in a
gain of +1 and has a unity-gain bandwidth of 50MHz, then
the output impedance at 50MHz should be less than
100Ω. The second requirement is that the closed-loop
bandwidth must be greater than 20MHz to ensure
adequate small-signal settling for full throughput rate. If
slower op amps are used, more settling time can be
provided by increasing the time between conversions.
The best choice for an op amp to drive the LTC1419 will
depend on the application. Generally applications fall into
two categories: AC applications where dynamic specifi-
cations are most critical and time domain applications
where DC accuracy and settling time are most critical.
The following list is a summary of the op amps that are
suitable for driving the LTC1419. More detailed informa-
tion is available in the Linear Technology databooks, the
LinearView
tech. com.
LinearView is a trademark of Linear Technology Corporation.
10
0.01
0.1
TM
10
1
0.01
Figure 6. t
CD-ROM and on our web site at www.linear-
U
SOURCE RESISTANCE (kΩ)
0.1
ACQ
INFORMATION
vs Source Resistance
U
1
10
W
1419 F06
100
U
LT
amplifier. ±5V to ±15V supplies. Excellent DC specifica-
tions.
LT1223: 100MHz video current feedback amplifier. ±5V
to ±15V supplies, 6mA supply current. Low distortion at
frequencies above 400kHz. Low noise. Good for AC
applications.
LT1227: 140MHz video current feedback amplifier. ±5V
to ±15V supplies, 10mA supply current. Lowest distor-
tion at frequencies above 400kHz. Low noise. Best for AC
applications.
LT1229/LT1230: Dual/quad 100MHz current feedback
amplifiers. ±2V to ±15V supplies, 6mA supply current
each amplifier. Low noise. Good AC specs.
LT1360: 50MHz voltage feedback amplifier. ±5V to ±15V
supplies, 3.8mA supply current. Good AC and DC specs.
LT1363: 70MHz, 1000V/µs op amps, 6.3mA supply cur-
rent. Good AC and DC specs.
LT1364/LT1365: Dual and quad 70MHz, 1000V/µs op
amps. 6.3mA supply current per amplifier.
Input Filtering
The noise and the distortion of the input amplifier and
other circuitry must be considered since they will add to
the LTC1419 noise and distortion. The small-signal band-
width of the sample-and-hold circuit is 20MHz. Any noise
or distortion products that are present at the analog inputs
will be summed over this entire bandwidth. Noisy input
circuitry should be filtered prior to the analog inputs to
minimize noise. A simple 1-pole RC filter is sufficient for
®
1220: 30MHz unity-gain bandwidth voltage feedback
ANALOG INPUT
Figure 7. RC Input Filter
1000pF
10µF
50Ω
1
2
3
4
5
+A
–A
V
REFCOMP
AGND
REF
IN
IN
LTC1419
1419 F07
1419fb