MAX194BEWE 데이터 시트보기 (PDF) - Maxim Integrated
부품명
상세내역
제조사
MAX194BEWE Datasheet PDF : 24 Pages
| |||
14-Bit, 85ksps ADC with 10µA Shutdown
1/2 74HC73
J
Q
+5V
K
CK
2 x CLK
CLOCK SHUTDOWN
CK
(2 x CLK)
Q
(CLK)
J
(CLOCK SHUTDOWN)
MAX194
CLK
BP/UP/SHDN
Figure 24. Circuit to Stop Free-Running Asynchronous CLK
-10
-30
-50
-70
-90
-110
-130
-150
0
fIN = 1kHz
fS = 85kHz
TA = +25°C
5 10 15 20 25 30 35 40
FREQUENCY (kHz)
Figure 25. MAX194 FFT Plot
measure of the ADC’s usefulness. Figure 26 shows the
effective number of bits as a function of the MAX194’s
input frequency calculated from the SINAD.
Total Harmonic Distortion
If a pure sine wave is input to an ADC, AC integral non-
linearity (INL) of an ADC’s transfer function results in
harmonics of the input frequency being present in the
sampled output data.
Total Harmonic Distortion (THD) is the ratio of the RMS
sum of all the harmonics (in the frequency band above
DC and below one-half the sample rate, but not includ-
ing the DC component) to the RMS amplitude of the
fundamental frequency. This is expressed as follows:
√(V22 + V32 + V42 + ... + VN2)
THD = 20log——————————————
V1
where V1 is the fundamental RMS amplitude, and V2
through VN are the amplitudes of the 2nd through Nth
harmonics. The THD specification in the Electrical
Characteristics includes the 2nd through 5th harmon-
ics. In the MAX194, this distortion is caused primarily
by the changes in on-resistance of the AIN sampling
switches with changing input voltage. These resistance
changes, together with the DAC’s capacitance (which
can also vary with input voltage), cause a varying time
delay for AC signals, which causes significant distortion
at moderately high frequencies (Figure 27).
______________________________________________________________________________________ 23
Share Link: 