MAX1492/MAX1494 Low-Power Analog-to-Digital Converters (ADCs)

The MAX1492/MAX1494 low-power, 3.5-1/2- or 4.5-1/2-digit analog-to-digital converters (ADCs) with integrated liquid crystal display (LCD) drivers operate from 2.7V to 5.25V. They include an internal reference, a high-precision on-chip oscillator, and a triple LCD driver. An internal charge pump generates a negative supply to power the integrated input buffers for single-supply operation. These ADCs have an input range that can be configured to ±2V or ±200mV and provide their conversion results to an LCD and/or a microcontroller (µC). The µC communicates through an SPI™/QSPI™/MICROWIRE™-compatible serial interface. The MAX1492 is a 3.5-1/2-digit (±1999 counts) device, and the MAX1494 is a 4.5-1/2-digit (±19,999 counts) device.

The MAX1492/MAX1494 do not require external precision integrating capacitors, self-zeroing capacitors, crystal oscillators, charge pumps, or other circuitry required for traditional dual-integrating ADCs (commonly used in panel meter circuits).

These devices also provide internal buffers for differential signals and reference inputs, allowing direct connection to high-impedance signal sources. In addition, they use continuous internal offset calibration to provide greater than 100dB of 50Hz and 60Hz noise rejection. Other features include data hold and peak hold, overrange/underrange detection, and low battery voltage monitoring.

The MAX1494 is available in a 32-pin, 7mm x 7mm LQFP package; the MAX1492 is available in a 28-pin SSOP or 28-pin PDIP package. All devices are specified over the 0°C to +70°C commercial temperature range.

Key Features

high resolution

MAX1494: 4.5 1/2 digits (±19,999 counts)

MAX1492: 3.5 1/2 digits (±1999 counts)

Sigma-Delta ADC Architecture

No integrating capacitor required

No need for self-calibration of zero capacitance

Provides greater than 100dB of 50Hz and 60Hz noise suppression

Operates from a 2.7V to 5.25V Single Supply

Selectable ±200mV or ±2V input range

Selectable voltage reference: internal 2.048V or external reference

Built-in high-precision oscillator, no external components required

Automatic offset calibration

Low power consumption

Maximum operating current 960µA

Shutdown current 400µA max

Small 32-pin 7mm x 7mm LQFP package (4.5 1/2 digits), 28-pin SSOP package (3.5 1/2 digits)

Triple LCD Driver

Compatible with SPI/QSPI/MICROWIRE serial interface

Evaluation kit available (order MAX1494EVKIT)