The MAX1497/MAX1499 low-power, 3.5- and 4.5-digit,
analog-to-digital converters (ADCs) with integrated lightemitting
diode (LED) 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 multiplexed
LED display driver. An internal charge pump
generates the negative supply needed to power the
integrated input buffers for single-supply operation. The
ADC is configurable for either a ±2V or ±200mV input
range and it outputs its conversion results to an LED
and/or to a microcontroller (µC). Microcontroller
communication is possible through an SPI-/QSPI-
/MICROWIRE-compatible serial interface. The
MAX1497 is a 3.5-digit (±1999 count) device and the
MAX1499 is a 4.5-digit (±19,999 count) device.
The MAX1497/MAX1499 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 rejection of 50Hz and 60Hz line noise.
Other features include data hold and peak detection,
overrange and underrange detection, and a user-programmable
low-battery monitor.
The MAX1499 is available in a 32-pin, 7mm x 7mm
TQFP package and the MAX1497 is available in 28-pin
SSOP and 28-pin PDIP packages. All devices in this
family operate over the -40°C to +85°C extended temperature
range.