A2C-SG2-M12
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8
ADC setup
The A2C-SG offers a very flexible frontend and ADC, that can be configures to various measurement applications.
The frontend contains a low noise, high precision 24bit sigma delta ADC with programmable gain amplifier and multiplexer.
8.1
Bipolar / Unipoloar configuration
The analog input to the A2C-SG can accept either unipolar or bipolar input voltage ranges. A bipolar input range does not imply that
the part can tolerate negative voltages with respect to sense. For strain gauge applications the Bipolar mode should be used.
When the gain stage is enabled, the output from the buffer is applied to the input of the programmable gain array (PGA).
Even at high gain of 128 the A2C-SG still maintaining excellent noise performance. For example, when the gain is set to 128, the
rms noise is 8.5 nV, typically, when the output data rate is 4.7 Hz. This is equivalent to 23 bits of effective resolution or 20.5 bits of
noise-free resolution. The A2C-SG can be programmed to have a gain of 1, 8, 16, 32, 64, and 128. Therefore, the bipolar input
voltage ranges are from ±19.53 mV to ±2.5 V with excitation voltage of 2.5V.
Mode
Buffer
Gain=1
Gain=8
Gain=16
Gain=32
Gain=64
Gain=128
2.5V excitation voltage
Bipolar
Enabled
±1250mV
±156.25mV ±78.13mV
±39.06mV
±19.53mV ±9.76mV
Disabled
±2.5V
±312.5mV
±156.2mV
±78.13mV
±39.06mV ±19.53mV
Unipolar
Enabled
+1250mV
+156.25mV +78.13mV
+39.06mV
+19.53mV +9.76mV
Disabled
5V excitation voltage
Bipolar
Enabled
±3750mV
±468.75mV ±234.36mV ±117.19mV ±58.59mV ±29.29mV
Disabled
±5.0V
±625mV
±312.5mV
±156.2mV
±78.13mV ±39.06mV
Unipolar
Enabled
+3750mV
+468.75mV +234.36mV +117.19mV +58.59mV +29.29mV
Disabled
Table 1