MX7705:16-Bit, Low-Power, 2-Channel, Sigma-Delta ADC

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.

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
MX7705: Functional Diagram
MX7705: Functional Diagram
Applications/Uses
  • Flow and Gas Meters
  • Industrial Instruments
  • Loop-Powered Systems
  • Medical Instrumentation
  • Pressure Transducers
  • RTD Measurements
  • Strain-Gauge Measurements
  • Thermocouple Measurements
  • Weigh Scales
DataSheet
titleDownload file
MX7705 Data SheetMX7705.pdf
Parametrics
Part NumberResolution
(bits)
Input Chan.Conv. Rate
(ksps)
ADC ArchitectureData BusDiff/S.E. InputExternal VREF
(V)
External VREF
(V)
Unipolar VIN
(V)
Bipolar VIN
(±V)
INL
(±LSB)
Package/PinsBudgetary
Price
ADCmaxminmaxmaxmaxSee Notes
MX77051620.5Sigma-DeltaSPIDiff. Only13.52.52.51.96608PDIP(N)/16
SOIC(W)/16
TSSOP/16
$4.34 @1k
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Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MX7705EPENo Longer AvailableMX7705EPE+PDIP(N),;16 pin;158.4 mm²-40°C to +85°CNo
MX7705EPE+ActivePDIP(N),;16 pin;158.4 mm²-40°C to +85°CLead Free
MX7705EUENo Longer AvailableMX7705EUE+TSSOP,;16 pin;33.4 mm²-40°C to +85°CNo
MX7705EUE+ActiveTSSOP,;16 pin;33.4 mm²-40°C to +85°CLead Free
MX7705EUE+TActiveTSSOP,;16 pin;33.4 mm²-40°C to +85°CLead Free
MX7705EUE-TNo Longer AvailableMX7705EUE+TTSSOP;16 pin-40°C to +85°CSee data sheet
MX7705EWENo Longer AvailableMX7705EWE+SOIC(W),;16 pin;111.8 mm²-40°C to +85°CNo
MX7705EWE+ActiveSOIC(W),;16 pin;111.8 mm²-40°C to +85°CLead Free
MX7705EWE+TActiveSOIC(W),;16 pin;111.8 mm²-40°C to +85°CLead Free
MX7705EWE-TNo Longer AvailableMX7705EWE+TW.SO;16 pin-40°C to +85°CSee data sheet
MX7705.pdf MX7705