XR19L400

The XR19L400 (L400) is a highly integrated device that combines a full-featured single channel Universal Asynchronous Receiver and Transmitter (UART) and RS-485 transceivers. The L400 is designed to operate with a 3.3V to 5V power supply. The L400 is fully compliant with RS-485 Standards.

The XR19L400 operates in four different modes: Active, Partial Sleep, Full Sleep and Power-Save. Each mode can be invoked via hardware or software. Upon power-up, the L400 is in the Active mode where the UART and RS-485 transceiver function normally. In the Partial Sleep mode, the internal crystal oscillator of the UART or charge pump of the RS-485 transceiver is turned off. In Full Sleep mode, both the crystal oscillator and the charge pump are turned off. While the UART is in the Sleep mode, the Power-Save mode isolates the core logic from the control signals (chip select, read/write strobes, address and data bus lines) to minimize the power consumption. The RS-485 receivers remain active in any of these four modes.