Rainbow Electronics MX7705 - Manual

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
♦ 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
♦ 16-Pin PDIP, SO, and TSSOP Packages
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
________________________________________________________________ Maxim Integrated Products 1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
SCLK GND
V DD
DIN
DOUT
DRDY
AIN2-
REF-
REF+
TOP VIEW
MX7705
PDIP/SO/TSSOP
CLKIN
CLKOUT
AIN2+
CS
RESET
AIN1+
AIN1-
Pin Configuration
Ordering Information
19-3051; Rev 0; 10/03
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.
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
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
*Future product—contact factory for availability.