MAX133:3¾ Digit DMM Circuit

The MAX133 and MAX134 are integrating A/D converters for 3¾ digit multimeters and data acquisition systems such as data loggers and weigh scales. The A/D's internal resolution is ±40,000 counts. An extra digit is supplied as a guard digit to allow autozero or tare of a 4000 count displayed reading to 1/10 of a displayed count. The conversion time is 50ms. The MAX133 and MAX134 differ only in their microprocessor interface. The MAX133 has a 4 bit multiplexed address/data bus while the MAX134 has 3 separate address lines and a 4 bit bidirectional data bus. Both devices can be used with 4, 8, and 16 bit microprocessors. When controlled by a microprocessor, the MAX133 and MAX134 can perform auto-ranging measurements from ±400.0mV to ±4000V full scale. External attenuator resistors are required, but range switching is performed by the A/D. The power supply is typically a 9V battery or ±5V. Operating current is typically 100µA while standby current is only 25µA.

Key Features
  • 40,000 Count Resolution
  • 0.025% Accuracy
  • 20 Conversions per Second
  • Microprocessor Interface
  • 100µA Operating Supply Current
  • Low External Component Count
  • 5µV Resolution
  • Demonstration Kit Available MAX134/DEMO
MAX133, MAX134: Pin Configuration
MAX133, MAX134: Pin Configuration
  • Data Acquisition Systems
  • Data Loggers
  • Digital Panel Meters
  • Weigh Scales
titleDownload file
MAX133-MAX134 Data SheetMAX133-MAX134.pdf
Part NumberResolution
Conv. Rate
Data BusDiff/S.E. InputExternal VREF
External VREF
Unipolar VIN
maxminmaxmaxSee Notes
MAX13340000.02µP/4Diff. Only0660.216MQFP/44
$14.89 @1k
Design kits & evaluation modules
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX133C/DNo Longer AvailableDICE;0°C to +70°CSee data sheet
MAX133CMH+DActiveMQFP,;44 pin;181.2 mm²0°C to +70°CLead Free
MAX133CMH+TDActiveMQFP,;44 pin;181.2 mm²0°C to +70°CLead Free
MAX133CMH-DNo Longer AvailableMAX133CMH+DMQFP;0°C to +70°CSee data sheet
MAX133CMH-TDNo Longer AvailableMAX133CMH+TDMQFP;0°C to +70°CSee data sheet
MAX133CPLNo Longer AvailableMAX133CPL+PDIP(W),;40 pin;836.5 mm²0°C to +70°CNo
MAX133CPL+ActivePDIP(W),;40 pin;836.5 mm²0°C to +70°CLead Free
MAX133CQH+DActivePLCC,;44 pin;311.5 mm²0°C to +70°CLead Free
MAX133CQH+TDActivePLCC,;44 pin;311.5 mm²0°C to +70°CLead Free
MAX133CQH-DNo Longer AvailableMAX133CQH+DPLCC,;44 pin;311.5 mm²0°C to +70°CNo
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX133CQH-TDNo Longer AvailableMAX133CQH+TDPLCC;44 pin0°C to +70°CSee data sheet
MAX133EPLNo Longer AvailableMAX133EPL+PDIP(W),;40 pin;836.5 mm²-40°C to +85°CNo
MAX133EPL+ActivePDIP(W),;40 pin;836.5 mm²-40°C to +85°CLead Free
MAX133EQH+DActivePLCC,;44 pin;311.5 mm²-40°C to +85°CLead Free
MAX133EQH+TDActivePLCC;44 pin-40°C to +85°CSee data sheet
MAX133EQH-DNo Longer AvailableMAX133EQH+DPLCC,;44 pin;311.5 mm²-40°C to +85°CNo
MAX133EQH-TDNo Longer AvailableMAX133EQH+TDPLCC;44 pin-40°C to +85°CSee data sheet
MAX133-MAX134.pdf MAX134
MAX133-MAX134.pdf MAX134