LT1185

The LT^®1185 is a 3A low dropout regulator with adjustablecurrent limit and remote sense capability. It can be used asa positive output regulator with floating input or as astandard negative regulator with grounded input. Theoutput voltage range is 2.5V to 25V, with ±1% accuracy onthe internal reference voltage.

The LT1185 uses a saturation-limited NPN transistor asthe pass element. This device gives the linear dropoutcharacteristics of an FET pass element with significantlyless die area. High efficiency is maintained by using specialanti-saturation circuitry that adjusts base drive to trackload current. The "on resistance" is typically 0.25Ω.

Accurate current limit is programmed with a single 1/8Wexternal resistor, with a range of zero to three amperes. Asecond, fixed internal limit circuit prevents destructivecurrents if the programming current is accidentally over-ranged. Shutdown of the regulator output is guaranteedwhen the program current is less than 1µA, allowingexternal logic control of output voltage.

The LT1185 has all the protection features of previous LTCregulators, including power limiting and thermal shut-down. The 4-lead TO-3 package is specified for 55°C to150°C operation and the 5-lead TO-220 is specified over0°C to 125°C.