Rainbow Electronics MAX1081 - Manual (Page 21)

MAX1080/MAX1081
300ksps/400ksps, Single-Supply, Low-Power,
8-Channel, Serial 10-Bit ADCs with Internal Reference
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Aperture Width
Aperture width (t AW ) is the time the T/H circuit requires
to disconnect the hold capacitor from the input circuit
(for instance, to turn off the sampling bridge and put
the T/H unit in hold mode).
Aperture Jitter
Aperture jitter (t AJ ) is the sample-to-sample variation in
the time between the samples.
Aperture Delay
Aperture delay (t AD ) is the time defined between the
rising edge of the sampling clock and the instant when
an actual sample is taken.
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital
samples, the SNR is the ratio of the full-scale analog
input (RMS value) to the RMS quantization error (resid-
ual error). The ideal, theoretical minimum analog-to-dig-
ital noise is caused only by quantization error and
results directly from the ADC’s resolution (N bits):
SNR = (6.02 ✕ N + 1.76)dB
In reality, there are other noise sources besides quanti-
zation noise, including thermal noise, reference noise,
clock jitter, etc. Therefore, SNR is calculated by taking
the ratio of the RMS signal to the RMS noise, which
includes all spectral components minus the fundamen-
tal, the first five harmonics, and the DC offset.
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16
15
14
13
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11
1
2
3
4
5
6
7
8
9
10
MAX1080
MAX1081
MC683XX
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
SHDN
V DD2
V DD1
SCLK
CS
DIN
SSTRB
DOUT
GND
REFADJ
REF V DD1
(POWER SUPPLIES)
SCK
PCS0
MOSI
MISO
0.1 µF 10 µF
(GND) 4.7 µF 0.01 µF
ANALOG
INPUTS
+5V
OR
+3V
+5V
OR
+3V
Figure 17. QSPI Connections
XF
CLKX
CLKR
DX
DR
FSR
CS
SCLK
DIN
DOUT
SSTRB
TMS320LC3x
MAX1080
MAX1081
Figure 18. MAX1080/MAX1081-to-TMS320 Serial Interface