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300mA Linear Voltage Regulator for Digital Applications



  • Operation from 1.65V to 3.6V Input
  • 1% accuracy at room temperature
  • Output Voltage from 1.2V to 2.8V
  • 125mV Dropout at 300mA load
  • 50 µA Quiescent Current at 1mA Load
  • Inrush Current controlled to 600mA
  • PSRR 65dB at 1kHz
  • 100 µs Start-Up time for 1.5VOUT
  • Stable with Ceramic capacitors as small as 0402
  • Thermal-Overload and Short-Circuit protection


  • Post DC/DC Regulator
  • Battery Operated Devices
  • Hand-Held Information Appliances


Texas Instruments  LP3991TL-1.2EV

The LP3991 is a 300mA Linear Voltage Regulator for Digital Applications. Operating from a minimum input voltage of 1.65V, the LP3991 regulator has been designed to provide fixed stable output voltages for load currents up to 300mA. This device is suitable where accurate, low voltages are required from low input voltage sources, and is therefore suitable for post regulation of switched mode regulators. In such applications, significant improvements in performance and EMI can be realized, with little reduction in overall efficiency. The LP3991 will provide fixed outputs as low as 1.2V from a wide input range of 1.65V to 3.6V. Using the enable pin, the device may be controlled to provide a shutdown state, in which negligible supply current is drawn.

The LP3991 is designed to be stable with space saving ceramic capacitors as small as 0402 case size.

Performance is specified for a -40°C to +125°C junction temperature range.

This board is designed to allow the evaluation of the LP3991 Low Voltage CMOS Regulator. Each board is pre-assembled and tested in the factory. The board contains the LP3991 in a 4 bump micro SMD package and input and output capacitors connected to GND. The LP3991 is capable of operating within input voltage as low as 1.65V for output voltage options of 1.5V or less. The LP3991 can supply a maximum output current of 300mA and is particularly suitable for powering digital circuits, where good transient behavior is required. It can be employed in applications requiring post regulation of switching regulators to provide maximum efficiency in battery powered products.