MX7705 Datasheet, PDF (1/34 Pages) Maxim Integrated Products – 16-Bit, Low-Power, 2-Channel, Sigma-Delta ADC

19-3051; Rev 0; 10/03
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
General Description
The MX7705 low-power, 2-channel, serial-output ana-
log-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 fea-
tures 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 perfor-
mance (±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 dif-
ferential 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 out-
put 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 sig-
nals to be directly acquired with little or no signal-condi-
tioning requirements.
The MX7705 is available in 16-pin PDIP, SO, and
TSSOP packages.
Applications
Industrial Instruments
Weigh Scales
Strain-Gauge Measurements
Loop-Powered Systems
Flow and Gas Meters
Medical Instrumentation
Pressure Transducers
Thermocouple Measurements
RTD Measurements
Features
o Pin Compatible and Software Compatible with the
AD7705
o 16-Bit Sigma-Delta ADC
o Two Fully Differential Input Channels
o 0.003% Integral Nonlinearity with No Missing Codes
o Interface with Schmitt Triggers on Inputs
o Internal Analog Input Buffers
o PGA from 1 to 128
o Single (2.7V to 3.6V) or (4.75V to 5.25V) Supply
o Low Power
1mW (max), 3V Supply
2µA (typ) Power-Down Current
o SPI-/QSPI-/MICROWIRE-Compatible 3-Wire Serial
Interface
o 16-Pin PDIP, SO, and TSSOP Packages
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MX7705EPE*
-40°C to +85°C 16 PDIP
MX7705EWE*
-40°C to +85°C 16 WIDE SO
MX7705EUE
-40°C to +85°C 16 TSSOP
*Future product—contact factory for availability.
Pin Configuration
TOP VIEW
SCLK ₁
CLKIN 2
CLKOUT 3
CS 4
RESET 5
AIN2+ 6
AIN1+ 7
AIN1- 8
MX7705
16 GND
15 V_DD
14 DIN
13 DOUT
12 DRDY
11 AIN2-
10 REF-
9 REF+
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
PDIP/SO/TSSOP
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.