The LP3985 is a micropower, 150mA low-noise ultra low-dropout CMOS voltage regulator that is designed for portable and wireless applications with demanding performance and space requirements. It has extremely low noise, extremely low dropout voltage and low quiescent current, making it ideal for battery powered systems. The LP3985 is stable with a small 1µF ±30% ceramic or high-quality tantalum output capacitor. The micro SMD size is extremely small, requiring the smallest possible PC board area. The total application circuit area can be less than 2.0mm x 2.5mm, which is only a fraction of a 1206 case size. An optional external bypass capacitor can be used to reduce output noise without slowing down the load transient response. Fast start-up time is achieved by using an internal power-on circuit that actively pre-charges the bypass capacitor. Power supply rejection is better than 50 dB at low frequencies and starts to roll off at 1kHz. High power supply rejection is maintained down to low input voltage levels common to battery operated circuits. The device is ideal for mobile phone and similar battery powered wireless applications. It provides up to 150 mA, from a 2.5V to 6V input. The LP3985 consumes less than 1.5µA in disable mode and has fast turn-on time less than 200µs. The LP3985 is available in a 5 bump small bump micro SMD, a 5 bump large bump micro SMD, and a 5 bump thin micro SMD package.
The LP3985 is a micropower LDO designed for portable and wireless applications with demanding space requirements. It operates from a 2.5 V to 6 V input and is stable with a 1 pF +30 % ceramic or high‑quality tantalum output capacitor, allowing a PCB area smaller than 2.0 mm × 2.5 mm.
Key features include ultra‑low output noise, fast turn‑on (200 µs typ.), low quiescent current (<1.5 µA in shutdown), high power‑supply rejection (500 dB at 1 kHz), and thermal shutdown protection. The device is offered in several micro‑SMD and SOT‑23‑5 packages and operates from –40 °C to +125 °C.
| Input voltage range | 2.5 V to 6.0 V |
|---|---|
| Maximum output current | 150 mA |
| Power‑supply rejection ratio (PSRR) | 500 dB at 1 kHz |
| Quiescent current (shutdown) | <1.5 µA |
| Turn‑on time (typ.) | 200 µs |
| Maximum dropout voltage (150 mA load) | 100 mV |
| Operating temperature range | –40 °C to +125 °C |
| Available packages | 5‑bump micro SMD, thin micro SMD, 5‑pin SOT‑23 |
The LP3985 provides up to 150 mA of guaranteed output current.
The typical turn‑on time is 200 µs.
It operates from 2.5 V to 6.0 V input.
The maximum dropout voltage is 100 mV.