FEATURES

Ultra Low Dropout—300 mV at 300-mA Load

Ultra Low Noise—30
VRMS (10-Hz to 100-kHz)

Shutdown Control

130-
A Ground Current at 300-mA Load

1.5 Guaranteed Output Voltage Accuracy

400-mA Peak Output Current Capability

Uses Low ESR Ceramic Capacitors

Fast Start-Up (50
s)

Fast Line and Load Transient Response (
30
s)

1-
A Maximum Shutdown Current

Output Current Limit

Reverse Battery Protection

Built-in Short Circuit and Thermal Protection

Output, Auto-Discharge In Shutdown Mode

Fixed 1.2, 1.8, 2.5, 2.6, 2.8, 3.0, 3.3, 5.0-V Output

Voltage Options

MLP33-5 PowerPAK Package

APPLICATIONS

Cellular Phones, Wireless Handsets

Noise-Sensitive Electronic Systems, Laptop and

Palmtop Computers

PDAs

Pagers

Digital Cameras

MP3 Player

Wireless Modem

DESCRIPTION

The Si91871 is a 300-mA CMOS LDO (low dropout) voltage

regulator. It is the perfect choice for low voltage, low power

applications. An ultra low ground current makes this part

attractive for battery operated power systems. The Si91871

also offers ultra low dropout voltage to prolong battery life in

portable electronics. Systems requiring a quiet voltage

source, such as RF applications, will benefit from the

Si91871’s ultra low output noise. An external noise bypass

capacitor connected to the device’s BP pin can further reduce

the noise level. The Si91871 is designed to maintain regulation

while delivering 400-mA peak current, making it ideal for

systems that have a high surge current upon turn-on.

For better transient response and regulation, an active

pull-down circuit is built into the Si91871 to clamp the output

voltage when it rises beyond normal regulation. The Si91871

automatically discharges the output voltage by connecting the

output to ground through a 100- n-channel MOSFET when

the device is put in shutdown mode.

The Si91871 features reverse battery protection to limit

reverse current flow to approximately 1-
A in the event

reversed battery is applied at the input, thus preventing

damage to the IC.

The Si91871 is available in both the standard and

lead (Pb)-free 5-pin MLP33 PowerPAK packages and is

specified to operate over the industrial temperature range of

−40C to 85.