features
Low Dropout Voltage Regulator, 1.2-V
150-mA Load Current Capability
Power Okay (POK) Function
Load Independent, Low Ground
Current,150-μA
Current Limiting
Thermal Shutdown
Low Sleep State Current (Off Mode)
Fast Transient Response
Low Variation Due to Load and Line
Regulation
Output Stable With Low ESR Capacitors
TTL Logic Controlled Enable Input

applications
Processor Powerup Sequencing
Palmtop Computers, Laptops, and
Notebooks

description
The SN105125 is a low dropout voltage regulator with an output tolerance of ±2% over the operating range. The
device is optimized for low noise applications and has a low quiescent current (enable <0.8 V). The device has
a low dropout voltage at full load (150 mA). The power okay function monitors the output voltage and indicates
when an error occurs in the system (active low). In the event of an output fault such as overcurrent, thermal
shutdown, or dropout, the power okay output is pulled low (open drain).
The SN105125 has a fast transient response recovery capability in the event of load transition from heavy load
to light load. The device also minimizes overshoot during this condition. During power down, the output
capacitor and load are de-energized through the internal active shutdown clamp, which is turned on when the
device is disabled.
The SN105125 requires a small output capacitor for stability with low ESR. An input capacitor is not required
unless the bulk ac capacitor is placed away from the device or the power supply is a battery. In this situation,
a 1-μF capacitor is recommended for the application. Low ESR ceramic capacitors may be used with the device
to reduce board space in power applications, a key concern in hand-held wireless devices.