LP3974数据手册集成电路（IC）的特殊用途稳压器规格书PDF

描述 Description

The LP3974 is designed to meet the power management requirements of the latest cellular phones. The LP3974 PMU contains asingle-input Li-Ion battery charger, 16 low-dropout voltage regulators (including 5 wide input low-output regulators, 2 over-voltageprotected voltage regulators, and 4 buck regulators), dual DPDT analog switches, real time clock, and backup battery charger.Programming is handled via an I2C-compatible high-speed Serial Interface allowing control of program on/off conditions and the output voltages of individualregulators, and to read status information of the PMU.
It can charge and maintain a single cell Li-Ion battery operating from an AC adapter or USB power source.
The Li-Ion charger requires few external components and integrates the power FET. Charging is thermally regulated to obtainthe most efficient charging rate for a given ambient temperature.
Over-Voltage Protection (OVP) circuit at the charger input protects the PMU from input voltages up to +28V, eliminating theneed for any external protection circuitry.
Buck regulators have an automatic switch to ECO mode at low load conditions providing very good efficiency at low output currents.
General-type LDO regulators provide excellent PSRR and ULTRA LOW NOISE, 45 μV typ., ideally suited for supplying voltage toRF section.
The real-time clock/calendar provides time interval information as well as two programmable alarms.
To accommodate different processor requirements, the LP3974 PMU can have three different default voltage settings and startupsequences selected by external pin.
Notice: This document is not a full datasheet. For more information regarding this product or to order samples please contact your local National Semiconductor sales office or visit http://www.national.com/support/dir.html

特性 Features

• Linear charger with single input
• USB or AC adapter input
• 28V OVP on the charger input
• Four high-efficiency Synchronous Magnetic Buck Regulators:
• 2 x 1A, 2 x 800 mA
• 2 regulators have DVS support
• High-efficiency ECO mode @ low IOUT
• Can be used with inductors as low as 1µH @ 4MHz clock
• Buck1, Buck2 and Buck4 have ramp control to change rate of change of output
• 11 General-type Low Noise LDOs
• 7 x 300 mA
• 2 x 450 mA
• 2 x 150 mA
• 5 wide-input low-output (WILO) LDOs
• 2 x 10 mA
• 1 x 50 mA
• 2 x 150 mA
• All LDOs S/W configurable
• Two over-voltage protected outputs for USB transceivers
• Real time clock with two alarms
• Back-up battery charger
• Momentary Power Loss detection
• Interrupt Request to reduce S/W polling
• I 2C-compatible Serial Interface
• 100-bump 0.4 mm pitch micro SMDxt package