MX7705

16-Bit, Low-Power, 2-Channel, Sigma-Delta ADC


Description

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 a 16-pin TSSOP package.
MX7705: Functional Diagram MX7705: Functional Diagram Enlarge+

Key Features

  • 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

Applications/Uses

  • Flow and Gas Meters
  • Industrial Instruments
  • Loop-Powered Systems
  • Medical Instrumentation
  • Pressure Transducers
  • RTD Measurements
  • Strain-Gauge Measurements
  • Thermocouple Measurements
  • Weigh Scales
Part Number Resolution
(bits)
Input Chan. Conv. Rate
(ksps)
ADC Architecture Data Bus Diff/S.E. Input External VREF
(V)
External VREF
(V)
Unipolar VIN
(V)
Bipolar VIN
(±V)
INL
(±LSB)
Package/Pins Budgetary
Price
ADC max min max max max See Notes
MX7705  16 2 0.5 Sigma-Delta SPI Diff. Only 1 3.5 2.5 2.5 1.96608
PDIP(N)/16
SOIC(W)/16
TSSOP/16
$4.34 @1k
See All Precision ADCs (< 5Msps) (469)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

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