MAX195 Maxim, MAX195 Datasheet - Page 23

• Manufacturer Part Number: MAX195
• Description: 16-Bit / 85ksps ADC with 10A Shutdown
• Manufacturer: Maxim

Figure 24. Circuit to Stop Free-Running Asynchronous CLK
Figure 25. MAX195 FFT Plot
(CLOCK SHUTDOWN)
-110
-130
-150
-10
-30
-50
-70
-90
0
(2 x CLK)
(CLK)
5
CK
Q
J
16-Bit, 85ksps ADC with 10µA Shutdown
______________________________________________________________________________________
10
CLOCK SHUTDOWN
15
FREQUENCY (kHz)
20
2 x CLK
25
+5V
30
f
f
T
IN
S
A
= 85kHz
= +25°C
= 1kHz
J
K
CK
35
1 / 2 74HC73
40
Q
Even better than oversampling and averaging is over-
sampling and digital filtering. Averaging is just a rough
(but computationally simple) type of digital filter. Finite
impulse response (and other) digital filter algorithms are
readily available, and are useful even with slow proces-
sors if the data rate is low or the data does not need to
be processed in real-time. When using averaging, be
sure to average an odd number of samples to avoid
small offset errors caused by asymmetrical rounding.
Whether simple averaging or more complex digital fil-
tering is used, the effect of oversampling is to spread
the noise across a wider bandwidth. Digital filtering or
averaging then eliminates the portion of this noise that
lies above the filter’s passband, leaving less noise in
the passband than if oversampling was not used. An
additional benefit of oversampling is that it simplifies
the design or choice of an anti-aliasing pre-filter for the
input. You can use a filter with a more gradual rolloff,
because the sample rate is much higher than the fre-
quency of interest.
CLK
BP/UP/SHDN
MAX195
23