35-Channel Contact Monitor

Monitor the Status of 35 Automotive Switches with a Single Microcontroller

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The MAX20091 is a 35-channel automotive contact monitor for automotive applications. Ten contact monitor inputs can be used with either ground- or battery-connected switches; the other 25 inputs are for use with ground-connected switches.

The IC operates over a 5.5V to 28V voltage range and withstands voltages up to 42V. It protects low-voltage circuitry from high voltages and reverse-battery conditions. The IC’s low-current operation under all operating conditions makes it suitable for use in electronic control units (ECUs) that are connected directly to the automotive battery. The IC has an adjustable scan mode that reduces the current drawn in key-off while maintaining polling capability.

The IC features an SPI interface to monitor the switch status and set the device configuration. An interrupt output allows the device to wake a local microcontroller when a switch status change is detected. In addition, a switch status change turns on the internal regulator.

The MAX20091 is available in a compact 48-pin TQFN package and operates over the -40°C to +125°C temperature range.

MAX20091: Functional Diagram MAX20091: Functional Diagram Enlarge+

Key Features

  • Reduces Cost by Eliminating Multiple Microprocessors for Switch-Monitoring Functions
    • Configurable Wetting Current Improves Switch Performance
    • SPI Interface for Control/Readback
    • Built-In Hysteresis and Deglitching
    • Interrupt Output to Processor
  • High Channel Count Reduces PCB Area Requirements
  • Very Low Operating Current Enables Scanning in Key-Off State with Minimal Current Draw from 12V Battery
    • Ultra-Low 88µA (typ) Operating Current in Polling Mode
  • Robust Switch Input Eliminate Need for External Protection Components
    • 5.5V to 28V Operating Voltage Range
    • Switch Inputs Withstand 42V and Reverse Battery
    • IN0-34 ESD Performance to ISO 10605 (In-Circuit): ±10kV Contact


  • Automotive Body Computers
  • Door Modules
  • Smart Junction Boxes

See parametric specs for Switch/Contact Monitors (4)

Part NumberFunctionsSwitch InputsSwitch Input Threshold
Switch Input Threshold Hysteresis
Output PolarityESD Protect.
MAX20091 Contact Monitor
1.8 to 4.30.2Active Low107.528130

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.
Request Reliability Report for: MAX20091 
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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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