DS275 Datasheet | Dallas Semiconducotr

FEATURES Low-power serial transmitter/receiver for battery-backed systems Transmitter steals power from receive signal line to save power Ultra-low static current, even when connected to RS-232-E port Variable transmitter level from +5 to +12 volts patible with RS-232-E signals Available in 8-pin, 150 mil wide SOIC package (DS275S) Low-power CMOS PIN ASSIGNMENT RXOUT VDRV TXIN GND 1 2 3 4 8 7 6 5 VCC RXIN NC TXOUT DS275 8-Pin DIP (300-mil) DS275 8-Pin SOIC (150-mil) RXOUT NC VDRV NC TXIN NC GND 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VCC NC NC RXIN NC NC TXOUT ORDERING INFORMATION DS275 DS275S DS275E 8-pin DIP 8-pin SOIC 14-pin TSSOP RXOUT VDRV TXIN GND TXOUT NC RXIN VCC DS275E 14-Pin TSSOP PIN DESCRIPTION - RS-232 Receiver Output - Transmit driver +V - RS-232 Driver Input - System Ground (0V) - RS-232 Driver Output - No Connection - RS-232 Receive Input -System Logic Supply (+5V) DESCRIPTION The DS275 Line-Powered RS-232 Transceiver Chip is a CMOS device that provides a low-cost, very low-power interface to RS-232 serial ports. The receiver input translates RS-232 signal levels to mon CMOS/TTL levels. The transmitter employs a unique circuit which steals current from the receive RS232 signal when that signal is in a negative state (marking). Since most serial munication ports remain in a negative state statically, using the receive signal for negative power greatly reduces the DS275’s static power consumption. This feature is especially important for battery-powered systems such as laptop puters, remote sensors, and portable medical instruments. During an actual munication session, the DS275’s transmitter will use system power (5-12 volts) for positive transitions while still employing the receive signal for negative transitions. 1 of 8 DS275 BLOCK DIAGRAM Figure 1 OPERATION Designed for the unique requirements of battery-backed systems, the DS275 provides a low-power halfduplex interface to an RS-232 serial port. Typically, a designer must use an...