Si91844

Features:

` Ultra Low Dropout-130 mV at 150-mA Load
` Low Noise-75 V(rms) (10-Hz to 100-kHz Bandwidth)
` Out-of-Regulation Error Flag (power good)
` Shutdown Control
` 110-A Ground Current at 150-mA Load
` Fast Start-Up (50 S)
` 1.5% Guaranteed Output Voltage Accuracy (1.2 V, 2%)
` 300-mA Peak Output Current Capability
` Uses Low ESR Ceramic Capacitors
` 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
` Si91842: Output-Auto-Discharge In Shutdown Mode
` Si91844: Output-No-Discharge In Shutdown Mode
` Fixed 1.2, 1.8, 2.0, 2.2, 2.5, 2.6, 2.7, 2.8, 2.85, 2.9, 3.0, 3.3, 3.5, 3.6, 5.0-V Output Voltage Options
` SOT23-5 Package


Application

· Cellular Phones, Wireless Handsets
· Noise-Sensitive Electronic Systems, Laptop and Palmtop Computers
· PDAs
· Pagers
· Digital Cameras
· MP3 Player
· Wireless Modem


Specifications

Input Voltage, V_IN to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 to 6.5 V
VERROR, VSD (See Detailed Description) . . . . . . . . . . . . . . . . . . . .0.3 V to V_IN
Output Current, I_OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . .Short Circuit Protected
Output Voltage, V_OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to VIN + 0.3 V
Package Power Dissipation, (P_d)^b . . . . . . . . . . . . . . . . . . . . . . . . . . .. .  440 mW
Package Thermal Resistance, (JA)a . . . . . . . . . . . . . . . . . . . . . . . . . . .180/W
Maximum Junction Temperature, T_J(max) . . . . . . . . . . . . . . . . . . . . . . . . . 150
Storage Temperature, T_STG . . . . . . . . . . . . . . . . . . . . . . . . . . . .65 to 150

Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 5.5 mW/ above T_A = 70


Description

The Si91842/4 is a 150-mA CMOS LDO (low dropout) voltage regulator. It is the perfect choice for low voltage, low power applications. An ultra low ground current and ultra fast turn-on make this part attractive for battery operated power systems.

The Si91842/4 also offers ultra low dropout voltage to prolong battery life in portable electronics. Systems requiring a quiet voltage source will benefit from the Si91842/4's low output noise. The Si91842/4 is designed to maintain regulation while delivering 300-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 Si91842/4 to clamp the output voltage when it rises beyond normal regulation. The Si91842 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 Si91842/4 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.