Parasitically Powered Digital Input

Industry's Smallest, Robust, Digital Input

Please check latest availability status for a specific part variant.


The MAX22191 is an IEC 61131-2 compliant, industrial digital input (DI) device that translates a 24V digital industrial input to a 2.4mA (typ) current for driving optical isolators. Voltage thresholds and current levels in the MAX22191 are compliant with Type 1 and Type 3 inputs, while minimizing power dissipation. The MAX22191 is also compliant with 48V inputs, with the addition of external resistors.

Operating power is derived from the input signal, eliminating the need for an external field-side power supply. A 250ns (max) fast response time is ideal for high-speed inputs. Additionally, a CMOS-compatible test input is available for safety diagnostics.

The MAX22191 features robust functionality for harsh industrial systems and is capable of normal operation with input signals ranging from -60V to +60V. Integrated thermal shutdown further protects the device when VCC is present.

The MAX22191 is available in a small, 6-lead SOT23 package and operates over the -40°C to +125°C ambient temperature range.

Design Solution: Worried About Heat in Your I/O Module? No Need to Sweat ›

MAX22191: Simplified Block Diagram MAX22191: Simplified Block Diagram Enlarge+

Key Features

  • High Integration for Flexible Circuit Designs
    • 250ns (max) Response Time
    • Parasitically Powered from the Field Input
    • Current Sourcing Input with Optical Isolators
    • Current Sinking Input with Optical Isolators
    • Current Sinking Input with Logic Devices
    • Test Pulse Input
  • Reduced Power and Heat Dissipation
    • Current Limited Input
  • Robust Design
    • Operates from -60V to +60V Input Voltage
    • -40°C to +125°C Ambient Operating Temperature


  • Current Sourcing Inputs
  • Individually Isolated Inputs
  • Industrial Automation
  • Motor Controls
  • Process Automation

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX22191EVKIT: Evaluation Kit for the MAX22191
MAX22191PMB: Evaluation Kit for the MAX22191 Peripheral Module
Request Reliability Report for: MAX22191 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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Type ID Title
Evaluation Board9719MAX22191EVKIT Evaluation Kit for the MAX22191
Evaluation Board10055MAX22191PMB Evaluation Kit for the MAX22191 Peripheral Module