MAX1280 Datasheet, PDF (21/24 Pages) Maxim Integrated Products – 400ksps/300ksps, Single-Supply, Low-Power, 8-Channel, Serial 12-Bit ADCs with Internal Reference

400ksps/300ksps, Single-Supply, Low-Power, 8-Channel,
Serial 12-Bit ADCs with Internal Reference
ANALOG
INPUTS
V_DD1
1 _CH0
V_{DD1 20}
2 _CH1
V_{DD2 19}
3 CH2
SCLK ₁₈
4 CH3 _MAX1280 ^CS 17
5
MAX1281
CH4
DIN ₁₆
6 CH5
7 CH6
SSTRB ₁₅
DOUT ₁₄
8 CH7
GND 13
9 COM
REFADJ 12
10 SHDN
REF 11
0.1µF
+3V OR +5V +3V OR +5V
10µF
(POWER SUPPLIES)
SCK
PCS0
MOSI
MC683XX
MISO
4.7µF
0.01µF
(GND)
Figure 17. QSPI Connections
XF
CLKX
TMS320LC3x
CLKR
DX
DR
FSR
CS
SCLK
MAX1280
MAX1281
DIN
DOUT
SSTRB
Figure 18. MAX1280/MAX1281-to-TMS320 Serial Interface
Aperture Delay
Aperture delay (t_AD) is the time defined between the
falling edge of the sampling clock and the instant when
an actual sample is taken.
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital
samples, Signal-to-noise ratio (SNR) is the ratio of full-
scale analog input (RMS value) to the RMS quantization
error (residual error). The ideal theoretical minimum
analog-to-digital noise is caused by quantization error
only 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.
Signal-to-Noise Plus Distortion
Signal-to-noise ratio plus distortion (SINAD) is the ratio
of the fundamental input frequency’s RMS amplitude to
RMS equivalent of all other ADC output signals.
SINAD (dB) = 20 ✕ log (Signal_RMS / Noise_RMS)
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