Datasheet

Measurement Computing [phone]
4
[e-mail] mccdaq.com
MCC 172
All specifications are subject to change without notice.
Typical for 25 ˚C unless otherwise specified.
Analog input
Number of channels: 2
ADC Resolution: 24 bits
A/D converter type: Delta sigma
Sampling mode: Simultaneous
Master timebase (f
M
):
Frequency: 26.2144 MHz
Accuracy: ±50 ppm max
Master timebase sources
Internal clock
Shared clock from another MCC 172
Data rates (fS)
(f
M
/ 512) / n, n = 1, 2, …, 256
51.2 kS/s max
200 S/s min
Input coupling: AC
AC cutoff frequency
-3 dB: 0.78 Hz
-0.1 dB: 5.2 Hz max
Input voltage range: ±5 V
Common-mode voltage range
CHx to AGND: ±2 V max
Overvoltage protection
CHx+ to CHx-: ±35 V
CHx- to ground: ±2.5 V
IEPE compliance voltage: 23 V max
IEPE excitation current: 4.0 mA min, 4.1 mA typ
Input delay
1 kHz to 23 kHz input frequency: 4.5 µs + 39 / f
S
Channel-to-channel matching
Phase (200 Hz to 23 kHz): (f
in
* 0.022°) max
Gain (20 Hz to 23 kHz): 0.19 dB typ
Passband
Frequency: 0.453 * f
S
Flatness (20 Hz to 23 kHz): 52 mdB (pk-to-pk max)
Phase nonlinearity
f
S
= 51.2 kS/s, 200 Hz to 23 kHz input frequency: ±0.36° max
Stopband
Frequency: 0.547 * f
S
Rejection: 99 dB min
Alias-free bandwidth: 0.453 * fS
Alias rejection: 100 dB @ 51.2 kS/s
Oversample rate: 128 * f
S
Crosstalk
1 kHz: -122 dB
SFDR
f
in
= 1 kHz, -60 dBFS: 120 dB
Dynamic range
f
in
= 1 kHz, -1 dBFS: 100 dB
Input impedance
Differential: 202 kΩ
AI- (shield) to ground: 50 Ω
Throughput
Single board: 102.4 kS/s max (51.2 kS/s × 2 channels)
Multiple boards: Up to 307.2 kS/s aggregate
†
†
Depends on the load on the Raspberry Pi processor and the SPI interface.
Note: For best results, connect the signal source and the Raspberry Pi to a common
ground. If a floating source is required, connect the MCC 172 to earth ground via
the DGND screw terminal to minimize common mode noise.
Specifications
Accuracy
Analog input AC voltage measurement accuracy
(all values are (±) and apply to calibrated readings)
Gain error,
max:
Offset error,
max:
Gain temperature
coefficient, max:
Gain temperature
coefficient, max:
0.43% 5.10 mV 88 ppm/°C 184 µV/°C
Noise performance
Idle Channel 51.2 kS/s
Noise 33 µVrms
Noise density 207 nV/√Hz
Total harmonic distortion (THD)
Input Amplitude 1 kHz 8 kHz
-1 dBFS -93 dB -91 dB
-10.96 dBFS -87 dB -87 dB
External digital trigger
Trigger source: TRIG input
Trigger mode: Software configurable for rising or falling edge, or high or low level
Trigger latency: 1 µs + 1 sample period (1/fS) max
Trigger pulse width: 100 ns min
Input type : Schmitt trigger, 100K pull-down to ground
Input high voltage threshold: 1.48 V min
Input low voltage threshold: 1.2 V max
Input hysteresis: 0.51 V min
Input voltage limits: 6.5 V absolute max, –0.5 V absolute min,
0 V recommended min
Memory
Data FIFO: 48 K (49,152) analog input samples
Non-volatile memory: 4 KB (ID and calibration storage, no user-modifiable
memory)
Power
Supply current, 5 V supply
Typical: 100 mA
Maximum: 140 mA
Interface
Raspberry Pi GPIO pins used:
GPIO 8, GPIO 9, GPIO 10, GPIO 11 (SPI interface)
ID_SD, ID_SC (ID EEPROM)
GPIO 12, GPIO 13, GPIO 26 (Board address)
GPIO 5, 6, 19, 16, 20 (Clock / trigger sharing, Reset, IRQ)
Data interface type: SPI slave device, CE0 chip select
SPI mode: 1
SPI clock rate: 18 MHz, max
Environment
Operating temperature: 0 °C to 55 °C
Storage temperature: –40 ˚C to 85 °C max
Relative humidity: 0% to 90% non-condensing
Mechanical
Dimensions (L × W × H): 65 × 56.5 × 12 mm (2.56 × 2.22 × 0.47 in.) max