1.5A negative LDO+ provides rail-to-rail operation, programmable current limiting, and output current monitor

     Linear Technology Corporation introduces the LT3091, the latest device in the LDO+™ family, A 1.5A low voltage differential negative linear regulator with low noise, rail-to-rail operation, precise programmable current limiting and a bidirectional output current monitor. The LT3091 provides cable voltage drop compensation, is easily shunt in parallel to provide higher current or improve board heat dissipation, and can be configured as a three-terminal floating regulator. The LT3091 has an input voltage range of -1.5V to -36V. A single resistor can be used to set adjustable rail-to-rail output voltage in the range of 0V to -32V, with a differential voltage of only 300mV (typical at full load).

     The device features a fine-tuned 50µA current source reference with ±1% accuracy, providing a ±2% output voltage tolerance over the entire voltage, load, and temperature range. Because the device uses a unit-gain voltage follower architecture, output voltage regulation, bandwidth, transient response, and output noise (18µVRMS in the 10Hz to 100kHz bandwidth range) are not affected by the output voltage. The LT3091 is ideal for negative logic power supplies, low noise instrument and RF power supplies, rugged industrial power supplies, and rear regulated switching power supplies.

     The LT3091 provides excellent stability with a variety of output capacitors, including small, low-cost ceramic capacitors. The device is stabilized with an output capacitor with a minimum value of 10µF. Precise programmable current limits can be adjusted with a single resistor. The device's bipolar current monitor provides or absorbs current proportional to the output current, which is useful for system monitoring. The LT3091's two-way shutdown capability enables the device to operate at positive or negative logic levels. In addition, the LT3091's accurate shutdown threshold provides a programmable UVLO threshold for the regulator's input power or positive system supply voltage. The internal protection circuit of the IC includes precise current limiting with reentry and overheating shutdown with hysteresis. In bipolar power applications where the voltage regulator's load returns to a positive power supply, the OUT pin can be pulled up to 34V higher than GND and still allow the LT3091 to start safely.

     The LT3091 comes in flat (0.75mm) 3mm x 4mm 14-lead DFN and 16-lead TSSOP packages, both with underside thermal pads. In addition, the device is available in TO-220-7 and DD-Pak-7 high-power packages. Class E and I versions operate from -40 °C to 125°C, Class H versions from -40 °C to 150°C, and MP versions are specified to operate in the widest temperature range from -55 °C to 150°C.