MAX1491CAI+

ADCs/DACs - Special Purpose Overview

The MAX1491CAI+ is a low-power, single-chip analog-to-digital converter (ADC) with an integrated triplexed liquid crystal display (LCD) driver. It provides 3.5-digit resolution (±1999 count) using a sigma-delta architecture. The device operates from a single 2.7V to 5.25V supply and includes an internal 2.048V reference, high-accuracy oscillator, and charge pump for negative supply generation. It features selectable input ranges of ±2V or ±200mV, >100dB simultaneous 50Hz/60Hz rejection, and automatic offset calibration. The MAX1491CAI+ is housed in a 28-pin SSOP package and operates over the 0°C to +70°C temperature range.

ADCs/DACs - Special Purpose Feature Summary

• Sigma-Delta ADC Architecture: Provides 3.5-digit resolution (±1999 count) with no external integrating or auto-zero capacitors required.
• Integrated LCD Driver: Includes a triplexed LCD driver with segment and backplane outputs for direct connection to displays.
• High Noise Rejection: Offers >100dB simultaneous rejection of 50Hz and 60Hz line noise via SINC4 digital filtering.
• Single-Supply Operation: Operates on a single 2.7V to 5.25V supply with an internal charge pump generating the necessary negative voltage.

ADCs/DACs - Special Purpose Applications

• Digital Panel Meters
• Hand-Held Meters
• Digital Voltmeters
• Digital Multimeters

ADCs/DACs - Special Purpose Procurement Notes

Verify the component status as the MAX1491 series may be discontinued or subject to limited availability. Confirm that the CAI suffix corresponds to the commercial temperature range (0°C to +70°C) and the 28-pin SSOP package. Ensure compatibility with existing PCB footprints for the SSOP-28 form factor before procurement.

ADCs/DACs - Special Purpose Selection Notes

Select the MAX1491CAI+ when 3.5-digit resolution is sufficient for the application. Choose this part over the MAX1493/MAX1495 if board space is constrained by the smaller 28-pin SSOP package compared to the 32-pin TQFP. Ensure the input signal range fits within the ±2V or ±200mV limits and that the operating environment remains within the commercial temperature range.

ADCs/DACs - Special Purpose Part Context

The MAX1491CAI+ belongs to the MAX1491/MAX1493/MAX1495 family of single-chip ADCs with LCD drivers. While the MAX1493 and MAX1495 offer 4.5-digit resolution in a 32-pin TQFP package, the MAX1491 provides 3.5-digit resolution in a more compact 28-pin SSOP or DIP package. All variants share the same core sigma-delta architecture and integrated peripheral features.

ADCs/DACs - Special Purpose Replacement Considerations

Direct pin-compatible replacements within the same family include the MAX1491CNI+ (28-pin DIP). For applications requiring higher resolution, the MAX1493CCJ+ or MAX1495CCJ+ are available but require a 32-pin TQFP footprint. No other cross-family substitutes are confirmed in the provided documentation.

ADCs/DACs - Special Purpose FAQ

What is the conversion rate of the MAX1491CAI+?

The MAX1491CAI+ has a fixed conversion rate of 5Hz.

How does the MAX1491CAI+ handle power supply noise?

It offers high power-supply rejection ratios (PSRR), typically 80dB for AVDD and 100dB for DVDD at DC, with even higher rejection at 50Hz and 60Hz frequencies.

Can the MAX1491CAI+ accept negative input voltages?

Yes, the device supports differential inputs with a range of ±2V or ±200mV. An internal charge pump generates a negative supply voltage (VNEG) to allow the input buffers to handle signals below ground.