The MX7705 low-power, 2-channel, serial-output analog-
to-digital converter (ADC) includes a sigma-delta
modulator with a digital filter to achieve 16-bit resolution
with no missing codes. This ADC is pin compatible and
software compatible with the AD7705. The MX7705 features
an on-chip input buffer and programmable-gain
amplifier (PGA). The device offers an SPI?-/QSPI?-/
MICROWIRE?-compatible serial interface.
The MX7705 operates from a single 2.7V to 5.25V supply.
The operating supply current is 320μA (typ) with a 3V
supply. Power-down mode reduces the supply current to
2μA (typ).
Self-calibration and system calibration allow the MX7705
to correct for gain and offset errors. Excellent DC performance
(±0.003% FSR INL) and low noise (650nV) make
the MX7705 ideal for measuring low-frequency signals
with a wide dynamic range. The device accepts fully differential
bipolar/unipolar inputs. An internal input buffer
allows for input signals with high source impedances. An
on-chip digital filter, with a programmable cutoff and output
data rate, processes the output of the sigma-delta
modulator. The first notch frequency of the digital filter is
chosen to provide 150dB rejection of common-mode
50Hz or 60Hz noise and 98dB rejection of normal-mode
50Hz or 60Hz noise. A PGA and digital filtering allow signals
to be directly acquired with little or no signal-conditioning
requirements.
The MX7705 is available in 16-pin PDIP, SO, and
TSSOP packages.