40V, 1.5A Robust Linear Regulator Has Current & Temperature Monitor Outputs

The LT3081 uses a current source reference for single resistor output voltage settings and output adjustability down to “0.” Output current limit can be set externally with a single resistor. This regulator architecture, combined with low millivolt regulation, enables multiple ICs to be paralleled easily for heat spreading and higher output current. The current from the device’s current monitor can be summed with the set current for line-drop compensation, where the output of the LT3081 increases with current to compensate for line drops.



The LT3081 achieves unmatched line and load regulation of under 2mV independent of output voltage and features an input voltage range from 1.2V to 40V. The device fits well in applications requiring multiple rails. Output voltage is programmable with a single resistor from 0V to 38.5V with a 1.2V dropout. The on-chip trimmed 50µA current reference is ±1% accurate. The regulation, transient response and output noise (30µVrms) are independent of output voltage due to the device’s voltage follower architecture. The LT3081 is configurable as a 2-terminal current source with just two resistors. Input or output capacitors for stability are optional in either linear regulator or current-source mode of operation.



The LT3081 provides several monitoring and protection functions. Current limit, accurate to ±10%, can be programmed with a single resistor. Monitor outputs provide a current output proportional to temperature (1µA/°C) and output current (200µA/A), allowing easy ground-based measurement. The current monitor can be used to compensate for cable drops. The LT3081’s internal protection circuitry includes reverse input protection, reverse-current protection, internal current limiting and thermal shutdown.



According to Robert Dobkin, Linear Technology’s Vice President, Engineering and CTO, “The LT3081 regulator’s robust architecture, protection and monitoring features provide designers with new tools for reliable design. A TO-220 package for high power dissipation and various surface mount packages for lower power applications are available. System power and temperature are easily checked for proper operation.”



The LT3081 is offered in a variety of thermally enhanced surface-mount compatible packages, including a low profile (0.75mm) 12-lead 4mm x 4mm DFN, a 16-lead thermally enhanced TSSOP and a 7-lead DD-Pak; all dissipate 2W in surface mount applications with no heat sink. The LT3081 is also available in a 7-lead TO-220 power package for vertical mounting to heat sinks for higher power dissipation capability. A wide variety of grades/temperature ranges are offered including: E & I grades -40°C to +125°C, H grade -40°C to +150°C and the high reliability MP grade -55°C to +150°C. 1,000-piece pricing starts at $2.60 each for the E grade.







Summary of Features: LT3081



•Rugged Industrial Linear Regulator



•Wide Safe Operating Area at 1.5A Output



•Output Current Monitor:



IMON = IOUT/5000



•Junction Temperature Monitor: 1µA/°C



•Wide Input Voltage Range: 1.2V to 40V



•Single Resistor Sets Output Voltage 0 to 38V



•50µA SET Pin Current: 1% Initial Accuracy



•Paralleled Easily for Higher Current or Heat Spreading



•Externally Settable Current Limit



•Input or Output Capacitors optional



•<1mV Load Regulation Typical



•<0.001%/V Line Regulation Typical



•Current Limit, Thermal Shutdown & Reverse Input Protection



•Available in Thermally Enhanced 12-Lead 4mm × 4mm DFN & 16-Lead TSSOP, 7-Lead DD-Pak & 7-Lead TO-220 Packages