The SN65HVS885 is an eight channel, digital-input serializer for high-channel density digital input modules in industrial and building automation. Operating from a 5-V supply the device accepts field input voltages of up to 34 V. In combination with galvanic isolators the device completes the interface between the high voltage signals on the field-side and the low-voltage signals on the controller side. Inputs signals are current limited and then validated by internal debounce filters.
With the addition of few external components, the input switching characteristic can be configured in accordance with IEC61131-2 for Type 1, 2 and 3 sensor switches.
Upon the application of load and clock signals, input data is latched in parallel into the shift register and afterwards clocked out serially.
Cascading of multiple devices is possible by connecting the serial output of the leading device with the serial input of the following device, enabling the design of high-channel count input modules. Multiple devices can be cascaded through a single serial port, reducing both the isolation channels and controller inputs required.
Input status can be visually indicated via constant current LED outputs. The current limit on the inputs is set by a single, external, precision resistor. An on-chip temperature sensor provides diagnostic information for graceful shutdown and system safety.
The SN65HVS885 is available in a 28-pin PWP PowerPAD package, allowing for efficient heat dissipation. The device is specified for operation at temperatures from 40°C to 125°C.