Mosaic embedded designs » Embedded controllers » Expansion I/O modules » Data acquisition module

The DA 24/7 WildcardTM
7 channels / 24 bit resolution analog data acquisition

A programmable gain, high resolution data acquisition system
available at low cost

high-resolution 24 bit data acqusition system with programmable gain

The 24/7 Data Acquisition Wildcard is your instrument's complete analog front end, offering exceptional resolution, excellent stability, and remarkable noise rejection. Ideal for high resolution, low frequency measurements and data logging, this I/O module accepts low level signals directly from transducers - it amplifies and conditions them - and it converts them with 24 bits of resolution with no missing codes performance.

Precision analog to digital converter

This analog-to-digital subsystem performs all the signal conditioning and conversion you need for up to seven input channels. Amplifier gain, low-pass filter corner frequency, and sampling rate are all software programmable using simple commands. This data acquisition system can extract highly accurate data, even from noisy sources with imperfect signal conditioning in electrically harsh environments. It has 256 times the resolution of standard 16-bit converters, but at comparable cost. Mosaic's 24/7 Data Acquisition Wildcard is the price-performance standard for high-resolution data acquisition systems.

This tiny 2" by 2.5" board is a member of the Wildcard series of mezzanine boards that connect to Mosaic embedded computers and instrument controllers.

Extensive input capability

Four true-differential, or seven pseudo-differential, overvoltage-protected, high-impedance analog input channels are available on a 24-pin header or screw terminals.

Programmable gain

The gain range on all channels is 1 to 128 allowing the input full scale range to be user-selectable from 0-20 mV to 0-2.5V for unipolar signals, or a genuine bipolar range of ± 20 mV, or a quasi-bipolar range of ± 2.5 V (where both inputs are in the range 0-5VDC).

In unbuffered mode the common mode range of the inputs is nominally 0-5V (precisely -30 mV to 5.03 V). In buffered mode the input impedance is very great at the expense of slightly reducing the common mode input range to 50 mV to 3.5 V.

On-Board reference

An on-board 2.5 V reference is accurate to ±5 mV. This reference is available for use by sensors requiring a reference or producing a proportionate output. An external reference may also be used.

Conversion rate and operating modes

Conversion rate is programmable from 4.8 Hz to over 1010 Hz. Other features under software control include self-calibration, system calibration, input gain, filter cutoff, channel selection, signal polarity, and bipolar or unipolar input ranges.

Input Impedance

In unbuffered mode the analog inputs are repeatedly switched through a 9 kOhm resistor into a 7 pf input sampling capacitor with a DC leakage current less than 1 nA. The maximum source impedance allowed for there to be no gain errors at the 16- or 20-bit level, in unbuffered mode, varies from 10 kOhm to 150 kOhm depending on the selected gain and the external capacitance.
In buffered mode the input impedance is very great with a <1 nA offset leakage current. This input current does not cause a gain error, but it does produce a small dc offset voltage in the source impedance. For example, a 10 kOhm source will cause an offset error of less than 10 uV.

Accuracy and Noise Rejection

The 24/7 Data Acquisition Wildcard features excellent static performance with 24-bit no missing codes, less than 2 uvolt rms effective output noise, and ±0.0015% linearity. Endpoint errors and the effects of temperature drift are eliminated by on-chip self-calibration, which removes zero- and full-scale errors.

The wildcard provides excellent rejection of power line interference. Normal mode rejection of 50 and 60 Hz exceeds 100 dB; common mode rejection is >150 dB.

Filtering

On-board digital filtering provides a low-pass filter with (sinx/x)3 response. For a first notch at 10 Hz, attenuation at 50 Hz and 60 Hz is better than 100 dB.

Specifications

A/D Type: 24-bit sigma-delta A/D converter
Programmable Gain: Precisely 1, 2, 4, 8, 16, 32, 64 or 128, software selectable
Input Range: Differential: ±2.5V with each input within -0.03 V to +5.03 V
Common Mode: -30 mV to 5.0 V unbuffered,
50 mV to 3.5V buffered
Analog Inputs: 4 fully differential or 7 pseudo-differential, protected to ± 70 volts continuous
Conversion Rate: Programmable to 1010 Hz, determines the effective resolution and filter cut-off frequency. For example:
Data
Rate
Filter
Cutoff
Effective
Resolution
10Hz2.6Hz21.5 bits
30Hz7.9 HZ20
100 Hz26 Hz18.5
500 Hz131 Hz13
Monotonicity: 24 bits at up to 60 Hz data rate
Linearity: 0.0015% FS at up to 60 Hz data rate
Noise Rejection: DC Common Mode: >90 dB
Normal Mode at 50/60 Hz: >100 dB
Common Mode at 50/60 Hz: >150 dB
Filter Setting: < 4x the data conversion period
Power: 5.5 to 14 v at 70 ma.
Size: 2.0 x 2.5 in.

Documentation and Pricing:

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Analog Data Acquisition Board | Analog to Digital Converter | 24-bit Resolution A/D | Data Logger