The MAX1492/MAX1494 low-power, 3.5- and 4.5-digit,
analog-to-digital converters (ADCs) with integrated liquid
crystal display (LCD) drivers operate from a single 2.7V
to 5.25V power supply. They include an internal reference,
a high-accuracy on-chip oscillator, and a triplexed
LCD driver. An internal charge pump generates the negative
supply needed to power the integrated input buffer
for single-supply operation. The ADC is configurable for
either a ±2V or ±200mV input range and outputs its conversion
results to an LCD and/or to a microcontroller
(µC). µC communication is facilitated through an
SPI-/QSPI-/MICROWIRE-compatible serial interface.
The MAX1492 is a 3.5-digit (±1999 count) device,
and the MAX1494 is a 4.5-digit (±19,999 count) device.
The MAX1492/MAX1494 do not require external-precision
integrating capacitors, autozero capacitors, crystal
oscillators, charge pumps, or other circuitry required
with dual-slope ADCs (commonly used in panel meter
circuits).
These devices also feature on-chip buffers for the differential
signal and reference inputs, allowing direct
interface with high-impedance signal sources. In addition,
they use continuous internal-offset calibration and
offer >100dB simultaneous rejection of 50Hz and 60Hz
line noise. Other features include data hold and peak
hold, overrange and underrange detection, and a lowbattery
monitor.
The MAX1494 comes in a 32-pin, 7mm x 7mm TQFP
package, and the MAX1492 comes in 28-pin SSOP and
28-pin PDIP packages. All devices in this family operate
over the 0°C to +70°C commercial temperature range.