The LP5951 is a low-power, 150mA low-dropout CMOS voltage regulator from National Semiconductor. The device is available in SOT23-5 and SC70-5 packages and offers an output voltage range of 1.3V to 3.3V. The input voltage range is 1.8V to 5.5V. The LP5951 features an extremely low quiescent current of 29µA and excellent line transient response of ±2mV. The device also features logic controlled enable (0.4V/0.9V) and fast turn-on time of 30µs. In addition, the LP5951 offers thermal-overload and short-circuit protection.
The LP5951 regulator is designed for portable, battery‑powered systems that need a stable output voltage and very low quiescent current. It features a shutdown mode that reduces power consumption to virtually zero, internal short‑circuit and over‑temperature protection, and excellent line transient response and PSRR.
The device is supplied in two small‑outline packages (SOT‑23‑5 and SC‑70‑5) with a simple five‑pin pinout: Vin, GND, EN, NC, and Vout. Ordering information, package markings, and detailed electrical characteristics—including output voltage range, input range, and thermal limits—are provided in the datasheet.
| Output voltage range | 1.3 V to 3.3 V |
|---|---|
| Input voltage range | 1.8 V to 5.5 V |
| Typical quiescent current | 29 µA typ. |
| Shutdown quiescent current | < 1 nA typ. |
| Maximum output current | 150 mA |
| Package options | SOT‑23‑5 and SC‑70‑5 |
| Operating temperature range | -40 °C to +125 °C |
| Power Supply Rejection Ratio (PSRR) | -60 dB at 1 kHz typ. |
| Turn‑on time | 30 ps typ. |
| Enable pin logic | Low = shutdown, High = normal operation |
The LP5951 draws about 29 µA of quiescent current in normal operation.
The device enters shutdown when the EN pin is driven low, reducing power consumption to virtually zero.
The regulator is offered in SOT‑23‑5 and SC‑70‑5 small‑outline packages.
It can be ordered with fixed output voltages from 1.3 V up to 3.3 V.