5962-8963701CA(2015) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
5962-8963701CA Datasheet PDF : 25 Pages
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AD637
Data Sheet
Table 7. Practical Values of CAV and C2 for Various Input Waveforms
Input Waveform
and Period
Absolute Value
Circuit Waveform
and Period
Minimum R × CAV
Time Constant
Recommended Standard Values for CAV and C2
for 1% Averaging Error @ 60 Hz with T = 16.6 ms
CAV (μF)
C2 (μF)
T
1/2T
1/2T
0.47
1.5
A
0V
Symmetrical Sine Wave
T
T
T
0.82
2.7
B
0V
Sine Wave with dc Offset
T
T
10 (T − T2)
6.8
22
C
T2
T2
0V
Pulse Train Waveform
T
T
10 (T − 2T2)
5.6
18
D
T2
0V
T2
1% Settling
Time
181 ms
325 ms
2.67 sec
2.17 sec
FREQUENCY RESPONSE
The frequency response of the AD637 at various signal levels is
shown in Figure 15. The dashed lines show the upper frequency
limits for 1%, 10%, and ±3 dB of additional error. For example,
note that for 1% additional error with a 2 V rms input, the
highest frequency allowable is 200 kHz. A 200 mV signal can
be measured with 1% error at signal frequencies up to 100 kHz.
To take full advantage of the wide bandwidth of the AD637,
use care in the selection of the input buffer amplifier. To ensure
that the input signal is accurately presented to the converter,
the input buffer must have a −3 dB bandwidth that is wider
than that of the AD637. Note the importance of slew rate in
this application. For example, the minimum slew rate required
for a 1 V rms, 5 MHz, sine wave input signal is 44 V/μs. The user
is cautioned that this is the minimum rising or falling slew rate
and that care must be exercised in the selection of the buffer
amplifier, because some amplifiers exhibit a two-to-one
difference between rising and falling slew rates. The AD845
is recommended as a precision input buffer.
10 7V RMS INPUT
2V RMS INPUT
1V RMS INPUT
1
100mV RMS INPUT
0.1
1%
10%
±3dB
0.01
10mV RMS INPUT
1k
10k
100k
1M
10M
INPUT FREQUENCY (Hz)
Figure 15. Frequency Response
Rev. L | Page 16 of 25
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