Analog Devices Inc./Maxim Integrated

The LTC1477/LTC1478 protected high side switches provide extremely low RDS(ON)switching with built-in protection against short-circuit and thermal overload conditions. A built-in charge pump generates gate drive higher than the supply voltage to fully enhance the internal NMOS switch. This switch has no parasitic body diode and therefore no current flows through the switch when it is turned off and the output is forced above the input supply voltage. (DMOS switches have parasitic body diodes that become forward biased under these conditions.)Two levels of protection are provided by the LTC1477/LTC1478. The first level of protection is short-circuit current limit which is set at 2A. The short-circuit current can be reduced to as low as 0.85A by disconnecting portions of the power device (see Applications Information). The second level of protection is provided by thermal overload protection which limits the die temperature to approximately 130°C.The LTC1477 single is available in 8-lead SO packaging. The LTC1478 dual is available in 16-lead SO packaging.ApplicationsNotebook Computer Power ManagementPower Supply/Load ProtectionSupply/Battery Switch-Over CircuitsCircuit Breaker FunctionPeripheral Power ProtectionReconstruction Filters

The LTC1481 is an ultralow power differential line transceiver designed for data transmission standard RS485 applications. It will also meet the requirements of RS422. The CMOS design offers significant power savings over its bipolar counterparts without sacrificing ruggedness against overload or ESD damage. Typical quiescent current is only 80µA while operating and less than 1µA in shutdown.The driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common mode range. Excessive power dissipation caused by bus contention or faults is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state. The receiver has a fail-safe feature which guarantees a high output state when the inputs are left open.The LTC1481 is fully specified over the commercial and extended industrial temperature range and is available in 8-pin PDIP and SO packages.ApplicationsBattery-Powered RS485/RS422 ApplicationsLow Power RS485/RS422 TransceiverLevel Translator