The MAX250CPD is a transceiver from Analog Devices / Maxim Integrated featuring RS232 protocol. It operates from 4.5V to 5.5V and has an operating temperature range of 0°C to 70°C.
The MAX251CPD+ is a full duplex transceiver from Analog Devices / Maxim Integrated, operating over a voltage range of 4.5V to 5.5V. It features 2 drivers and 2 receivers and supports the RS232 protocol.