Octal Industrial Digital Input with Diagnostics

The MAX22190 is an IEC 61131-2 compliant industrial digital input device. The MAX22190 translates eight, 24V current-sinking, industrial inputs to a serialized SPI-compatible output that interfaces with 3V to 5.5V logic. A current setting resistor allows the MAX22190 to be configured for Type 1, Type 2, or Type 3 inputs. Field wiring is verified for proximity switches, by a second threshold detector on each input. When wire-break is enabled, the active-low FAULT output is asserted and a register flag is set if the input current drops below the wire-break threshold for more than 20ms. Additional diagnostics that assert the active-ow FAULT pin include: overtemperature, low 24V field supply, 24V field supply missing, CRC communication error, etc.

For robust operation in industrial environments, each input includes a programmable glitch filter. The filter delay on each channel can be independently programmed to one of eight values between 50μs and 20ms, or filter bypass.

The MAX22190 has a 4-pin SPI interface and in addition uses the active-low LATCH input for synchronizing input data across multiple devices in parallel.

MAX22190 field-side accepts a single 7V to 65V supply to VDD24 pin. When powered by the field supply, MAX22190 generates a 3.3V output from an integrated LDO regulator, which can provide up to 25mA of current for external loads in addition to powering the MAX22190. Alternatively, MAX22190 can be powered from a 3.0V to 5.5V logic side supply connected to VDD pin. For flexibility, the SPI interface operates at 3.3V or 5V logic levels as controlled by the VL pin.

Design Solution: Industrial Digital Inputs: They’re Not Quite as Simple as Counting from 0 to 1 ›

Applications

* Building Automation * Industrial Automation * Process Automation * Programmable Logic Controllers

* High Integration Reduces BOM Count and Board Space

* Eight Input Channels with Serializer

* Operates Directly from Field Supply (7V to 65V)

* Compatible with 3.3V or 5V Logic

* 5mm x 5mm TQFN Package

* Reduced Power and Heat Dissipation

* Accurate Input-Current Limiters

* Energyless Field-Side LED Drivers

* Fault Tolerant with Built-In Diagnostics

* Input Protection to ±40V with Low-Input Leakage Current

* Wire Break Detection

* Integrated Field-Supply Voltage Monitors

* Integrated Overtemperature Monitors

* 5-Bit CRC Code Generation and Transmission for Error Detection

* Configurability Enables Wide Range of Applications

* Configurable IEC 61131-2 Type 1, 2, 3 Inputs

* Configurable Input Current-Limiting from 0.5mA to 3.4mA

* Selectable Input Debounce Filtering

* Robust Design

* ±8kV Contact ESD and ±15kV Air Gap ESD Using Minimum 1kΩ Resistor

* ±1kV Surge Tolerant Using Minimum 1kΩ Resistor

* -40°C to +125°C Ambient Operating Temperature