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.
Key Features
Applications/Uses
Pin Compatible and Software Compatible with the AD7705
16-Bit Sigma-Delta ADC
Two Fully Differential Input Channels
0.003% Integral Nonlinearity with No Missing Codes
Interface with Schmitt Triggers on Inputs
Internal Analog Input Buffers
PGA from 1 to 128
Single (2.7V to 3.6V) or (4.75V to 5.25V) Supply
Low Power
1mW (max), 3V Supply
2µA (typ) Power-Down Current
SPI-/QSPI-/MICROWIRE-Compatible 3-Wire Serial Interface
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