The MAX22199 is an IEC 61131-2 compliant industrial digital input device. The MAX22199 translates eight 24V current-sinking industrial inputs to a serialized SPI-compatible output that interfaces with 3V to 5.5V logic. It can operate as eight Type 1/Type 3 digital inputs or four Type 2 digital inputs. The device provides diagnostic functions, including thermal shutdown, 24V under voltage alarm, 24V missing voltage alarm, and SPI and CRC communication error detection. All of the faults can be configured to generate an interrupt using the active-low FAULT pin.For robust operation in industrial environments, each input includes a programmable glitch filter. Noise filters on each channel can be independently programmed to one of eight values between 50µs and 20ms or filter bypass.The MAX22199 has a 4-pin SPI interface and, in addition, uses the active-low LATCH input for synchronizing input data sampling across multiple devices.The MAX22199 field-side accepts a single 7V to 65V supply to the VDD24pin. When powered by the field supply, the MAX22199 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 MAX22199. Alternatively, the MAX22199 can be powered from a 3.0V to 5.5V logic side supply connected to the VDDpin. For flexibility, the SPI interface operates at 3.3V or 5V logic levels as controlled by the VLpin.ApplicationsBuilding AutomationDistributed Control SystemMotor ControlProgrammable Logic Controllers