3.5- and 4.5-Digit Panel-Meter ADCs Feature 4-20mA Current Output
SUNNYVALE, CA-March 13, 2006-Maxim Integrated
Products (NASDAQ: MXIM) introduces the
MAX1365-MAX1368 stand-alone panel meters. These devices feature sigma-delta ADCs which digitize
fully differential analog signals in the ±2V and
±200mV range and display the results with 3.5- or
4.5-digit resolution on a local LED display. The
MAX1365-MAX1368 integrate a 4-20mA current
transmitter to drive a remote panel-meter or
other 4-20mA input. With their high performance,
integrated LED display drivers, and integrated
4-20mA output, these panel meter ICs are ideal
for industrial sensor applications.
The MAX1365-MAX1368 eliminate the need for
sensitive and costly external components to
achieve their high level of performance.
Traditional panel meters based on dual-slope
integrating ADC architectures rely on external
capacitors to achieve specified performance.
Additionally, they may require external clock
sources and external references to complete the
system. In contrast, each MAX1365-MAX1368 device
includes a 20-bit sigma-delta ADC, an internal
2.048V reference and an internal oscillator,
which means that they eliminate the need for
precision external capacitors. They also
integrate a common-cathode 7-segment LED display
driver, ±15-bit DAC, and precision 4-20mA current
transmitter in a 7mm x 7mm, 48-pin TQFP package.
The current output is accurate to within ±0.5%
(typ) gain error and ±10 µA (typ) offset
error. A fourth-order SINC4 digital filter
simultaneously rejects 100dB of both 50Hz and
60Hz noise. On-chip input buffers provide 100MΩ input impedance on the fully differential analog and reference inputs. Transparent offset
calibration automatically corrects offset errors.
The integrated LED display on the stand-alone
4.5-digit MAX1365 and 3.5-digit MAX1367 shows the
analog measurement while the 4-20mA current
output transmits a signal proportional to the
analog inputs.
For ultimate flexibility, the MAX1366 (4.5 digit)
and the MAX1368 (3.5 digit) ADCs provide a
microcontroller interface which allows
independent access and control of the ADC, LED
display, and current output through a
SPI™-/QSPI™-/MICROWIRE™-compatible
interface. This independent operation allows
pre-processing of the ADC results before they
appear on the LED display. It also allows the
4-20 mA current output to be used independently
of both the ADC results and the value shown on
the LED display. Such flexibility makes the
MAX1366/MAX1368 ideal for nonlinear measurements
like thermocouples, or for multifunction
microprocessor-based panel-meter products.
The MAX1365-MAX1368 operate off a 2.7V to 5.25V
ADC/DAC supply, 4.75V to 5.25V V/I converter
supply, and a 7V to 30V supply for the 4-20mA
current loop output. The devices are available in
a 7mm x 7mm, 48-pin TQFP package in the extended
(-40° Celsius to +85° Celsius)
temperature range. Prices start at $6.96
(1000-up, FOB USA).
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