Rugged 36V, 800mA linear regulators with extended safe working area and current and temperature monitoring outputs

     Linear Technology Corporation introduces the rugged 800mA wide input voltage range linear regulator, the LT3089, which provides critical availability, monitoring and protection functions. The LT3089 extends the safe working area (SOA) compared to existing regulators, making it ideal for applications with high input-to-output voltages and high output currents, where older regulators limit output. The LT3089 uses a current source reference for single-resistor output voltage setting and output tunability down to 0V.

     The output current limit can be set externally with a single resistor. The architecture of this regulator, combined with very low millivolt level voltage and load regulation capabilities, makes it very easy to connect multiple ics in parallel for heat dissipation and increased output current. The current from the device's current monitor can be added to a set current to achieve line voltage drop compensation, in which case the LT3089's output increases its current to compensate for line voltage drop.

     The LT3089 provides unmatched voltage and load regulation below 2mV, independent of output voltage, with an input voltage range of 1.2V to 36V. The device is ideal for applications that require multiple power rails. The output voltage can be programmed with a single resistor, setting the range from 0V to 34.5V, with a pressure difference of 1.2V. The fine-tuned internal 50µA current reference has an accuracy of ±1%. Due to the device's voltage follower architecture, regulation, transient response, and output noise (27µVRMS) are not affected by the output voltage. The LT3089 can be configured as a two-terminal current source with only two resistors. When operating in linear voltage regulator mode or current source mode, input or output capacitors for stability are optional.

     The LT3089 provides several monitoring and protection functions. Current limits can be set with a single resistor. The monitor output provides A current output proportional to temperature (1µA/°C) and output current (200µA/A), allowing very easy ground-based measurements. The current monitor can be used to compensate for the cable voltage drop. The LT3089's internal protection circuitry includes input reverse protection, current reverse protection, internal current limiting, and overheat shutdown.

     Robert Dobkin, vice president of engineering and chief Technology officer at Linear Technology, said: "The LT3089 regulator's robust architecture and protection and monitoring capabilities enable designers to achieve reliable designs in new ways. We offer DD-Pak packages for high power consumption and a variety of surface mount packages for lower power applications. System power and temperature are easily checked for normal operation."

     The LT3089 is available in a variety of heat-resistant enhanced surface-compatible packages, including flat (0.75mm) 12-lead 4mm x 4mm DFN, 16-lead Heat-resistant Enhanced TSSOP and 7-lead DD-Pak packages for surface mount applications. All versions consume 2W of power without the use of a heat sink. These devices are available in a variety of class/temperature range versions, including Class E and I (-40 °C to 125°C), Class H (-40 °C to 150°C), and high reliability MP (-55 °C to 150°C).