MAX1491:3.5- and 4.5-Digit, Single-Chip ADCs with LCD Drivers

3.5- and 4.5-Digit ADC, LED Display Drivers Reduce Time and Save Board Space

The MAX1491/MAX1493/MAX1495 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 it outputs its conversion results to an LCD. The MAX1491 is a 3.5-digit (±1999 count) device, and the MAX1493/MAX1495 are 4.5-digit (±19,999 count) devices. The MAX1491/MAX1493/MAX1495 do not require external-precision integrating or auto-zero 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, the MAX1491/MAX1493/MAX1495 use continuous internal offset calibration, and offer >100dB rejection of 50Hz and 60Hz line noise. The MAX1493/MAX1495 perform enhanced offset calibration at power-up. The MAX1495 also performs enhanced calibration on demand. Other features include data hold and peak hold, and a user programmable low-battery monitor. The MAX1493/MAX1495 come in a 32-pin 7mm x 7mm TQFP package, and the MAX1491 comes in 28-pin SSOP and 28-pin DIP packages. All devices in this family operate over the 0°C to +70°C commercial temperature range.

Key Features
  • High Resolution
    • MAX1495: 4.5 Digits (±19,999 Count)
    • MAX1493: 4.5 Digits (±19,999 Count)
    • MAX1491: 3.5 Digits (±1999 Count)
  • Sigma-Delta ADC Architecture
    • No Integrating Capacitors Required
    • No Autozeroing Capacitors Required
    • >100dB of Simultaneous 50Hz and 60Hz Rejection
  • Operate from a Single 2.7V or 5.25V Supply
  • Selectable Input Range of ±200mV or ±2V
  • Selectable Voltage Reference: Internal 2.048V or External
  • Internal High-Accuracy Oscillator Needs No External Components
  • Automatic Offset Calibration
  • Low Power: Maximum 980µA Operating Current
  • Small 32-Pin 7mm x 7mm TQFP Package (4.5 Digits), 28-Pin SSOP Package (3.5 Digits), and 28-Pin DIP Package (3.5 Digits)
  • Triplexed LCD Driver
  • Evaluation Kit Available (Order MAX1494EVKIT)
MAX1491, MAX1493, MAX1495: Typical Operating Circuit
MAX1491, MAX1493, MAX1495: Typical Operating Circuit
  • Digital Multimeters
  • Digital Panel Meters
  • Digital Voltmeters
  • Handheld meters
titleDownload file
MAX1491-MAX1495 Data SheetMAX1491-MAX1495.pdf
Part NumberResolution
Conv. Rate
Data BusDiff/S.E. InputInternal VREF
External VREF
External VREF
Bipolar VIN
maxnominalminmaxmaxSee Notes
MAX149120000.00257-SegmentDiff. Only2.04802.04821PDIP(N)/28
$5.52 @1k
MAX149320000LQFP/32$7.79 @1k
MAX149520000LQFP/32$10.47 @500
Design kits & evaluation modules
Related Products
  • MAX1496:3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers
  • MAX1447:3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers
  • MAX1498:3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers
  • MAX1499:3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers and µC Interface
  • MAX1497:3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers and µC Interface
  • MAX1494:3.5- and 4.5-Digit, Single-Chip ADCs with LCD Drivers
  • MAX1492:3.5- and 4.5-Digit, Single-Chip ADCs with LCD Drivers
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX1491CAINo Longer AvailableMAX1491CAI+SSOP,;28 pin;81.6 mm²0°C to +70°CSee data sheet
MAX1491CAI+ActiveSSOP,;28 pin;81.6 mm²0°C to +70°CLead Free
MAX1491CAI+TActiveSSOP,;28 pin;81.6 mm²0°C to +70°CLead Free
MAX1491CAI-TNo Longer AvailableMAX1491CAI+TSSOP;28 pin0°C to +70°CSee data sheet
MAX1491CNINo Longer AvailableMAX1491CNI+PDIP(N),;28 pin;289.5 mm²0°C to +70°CNo
MAX1491CNI+No Longer AvailablePDIP(N),;28 pin;289.5 mm²0°C to +70°CLead Free
MAX1491-MAX1495.pdf MAX1495
Delta-Sigma ADCs Replace Integrating ADCs for Panel Meters MAX1499
MAX1491-MAX1495.pdf MAX1495