The SP335 is an advanced multiprotocol transceiver supporting RS-232, RS-485, and RS-422 serial standards. Integrated cable termination and multiple configuration modes allow all three protocols to be used interchangeably over a single cable or connector with no additional switching components. Full operation requires only four external charge pump capacitors.
The RS-485/RS-232 mode pin selects RS-485 mode when high, and RS-232 mode when low. In RS-485 mode, the TERM pin enables the differential 120Ω termination, and the HALF/FULL pin configures the transceiver as either half or full duplex.
The high speed drivers operate up to 20Mbps in RS-485/422 modes, and up to 1Mbps in RS-232 mode. All drivers can be slew limited to 250kbps in any mode to minimize electromagnetic interference (EMI) by setting the dedicated SLEW pin low.
All transmitter outputs and receiver inputs feature robust electrostatic discharge (ESD) protection to ±15kV IEC 61000-4-2 Airgap, ±15kV Human Body Model (HBM) and ±8kV IEC 61000-4-2 Contact. Each receiver output has full fail-safe protection to avoid system lockup, oscillation, or indeterminate states by defaulting to logic-high output level when the inputs are open, shorted, or terminated but undriven. No external biasing resistors are required.
The RS-232 receiver inputs include a 5kΩ pull-down to ground when in RS-232 mode. The RS-485/422 receiver inputs are high impedance (>96kΩ when termination is disabled), allowing up to 256 devices on a single communication bus (1/8th unit load).
The SP335 operates from a single power supply, either 3.3V or 5V, with low idle current. The shutdown mode consumes less than 1µA in low power standby operation with RS-232 receivers enabled.