LP3974 LP3974 PRODUCT BRIEF High Performance Power Management Unit for Application Processors Literature Number: SNVS645A October 19, 2011 High Performance Power Management Unit for Application Processors General Description Features The LP3974 is designed to meet the power management requirements of the latest cellular phones. The LP3974 PMU contains a single-input Li-Ion battery charger, 16 low-dropout voltage regulators (including 5 wide input low-output regulators, 2 over-voltage protected voltage regulators, and 4 buck regulators), dual DPDT analog switches, real time clock, and backup battery charger. Programming is handled via an I2Ccompatible high-speed Serial Interface allowing control of program on/off conditions and the output voltages of individual regulators, 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 obtain the 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 the need 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 to RF 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 startup sequences 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 ■ 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 I2C-compatible Serial Interface 100-bump 0.4 mm pitch micro SMDxt package Applications ■ Smartphones ■ GSM, GPRS, EDGE, CDMA & WCDMA Handsets Notice: For more information regarding this product, to order samples, or for further information, please contact your local National Semiconductor sales office. © 2011 National Semiconductor Corporation 301130 www.national.com LP3974 PRODUCT BRIEF LP3974 PRODUCT BRIEF LP3974 Typical Application Diagram 30113001 www.national.com 2 LP3974 Device Pin Diagram 30113002 TOP VIEW 100–Bump (0.4 mm pitch) micro SMDxt Package Package Marking Information 30113003 Ordering Information Order Number Production Identification Supplied as LP3974RME/NOPB 3974 250 Tape & Reel LP3974RMX/NOPB 3974 1000 Tape & Reel 3 www.national.com LP3974 WILO-Type LDOs Wide Input Low Output LDOs are designed to enable a lowered output voltage range with voltages down to 0.8V. Operational Description The LP3974 is designed for the charging and voltage rail requirements within mobile handsets. The linear charger accepts DC voltages to provide the correct charging and charge maintenance profile for LI-Ion batteries. The charger outputs are programmable to meet the varying needs of these types of batteries. Powered from the Battery input to the device, 4 switching regulators and 16 LDO type linear regulators provide for distributed power within the handset. SINGLE INPUT LINEAR CHARGER LP3974 has a built-in Li-Ion/Li-Poly battery management system. Its main features are: • One input - AC adapter or USB • Integrated PMOS power routing switch • CC/CV linear charging • Selectable battery regulation voltage • Flexible charging cycle control • Wide array of charging current options • Safety timer with time doubling Application Information BUCK INFORMATION The LP3974 has four integrated high-efficiency step-down DC-DC switching buck converters that deliver a constant voltage from a single cell battery to portable devices. Using voltage mode architecture with synchronous rectification, Bucks 1 and 2 have the ability to deliver up to 1A, Bucks 3 and 4 up to 800 mA, depending on the input voltage and output voltage, ambient temperature, and the inductor chosen. There are two modes of operation depending on the current required – PWM (Pulse Width Modulation), ECO (ECOnomy) mode. The device operates in PWM mode at load currents of approximately 50 mA (typ.) or higher. Lighter output current loads cause the device to automatically switch into ECO mode for reduced current consumption and a longer battery life. Buck1 has DVS capability using external SET1, SET2 inputs while Buck2 has DVS capability via SET3 input. Additional features include soft-start, under voltage protection, current overload protection, and thermal shutdown protection. Only three external power components per buck are required for implementation. Charger Function A charge management system allowing safe charge and maintenance of a Li-Ion battery is implemented on the LP3974. Following the correct detection of a voltage at the charger input, the charger enters pre-charge mode. In this mode the battery is charged with a small constant current. Settings for the battery current in pre-charge mode, full-rate voltage level, and maximum pre-charge time are pre-set during factory test. In full charging mode full rate constant current is applied to the battery to raise the voltage to the termination level. The charging current is programmable. When termination voltage is reached, the charger is in constant voltage mode and a constant voltage is maintained. After reaching the end-ofcharge condition, the charge management isolates the battery and enters the maintenance mode. A maintenance mode enables the battery voltage to be maintained at the correct level. If restart conditions have been met, then the charge cycle is re-initiated to re-establish the termination voltage level. LDO INFORMATION All LDOs can be programmed through serial interface for different output voltage values which are summarized in the output voltage selection tables below. At the PMU power on, LDOs start up according to the selected startup sequence and the default voltages. For stability all LDOs need to have external capacitors with recommended value of 1µF connected to the output . It is important to select the type of capacitor whose capacitance will in no case (voltage, temperature, etc) be outside of limits specified in the LDO electrical characteristics. BACKUP BATTERY CHARGER Backup battery charger (BBC) is intended for charging an external coin battery. It consists of Voltage Limited Current Source with 1kΩ output resistor. By default it is always on and the output will be active when the supply voltage is above the UVLO threshold typically 2.7V. The output voltage is programmable to 5 voltages from 2.9V to 3.3V. The default output is set to 3.0V. It is possible to turn backup battery charger off via registers. BBC has a reverse current protection. General-Type LDOs The general LDOs are optimized to supply both analog and digital loads having LOW NOISE (45 µVRMS for IOUT > 5mA) and excellent PSRR (65 dB at 10 kHz) performance. They can be programmed through the serial interface for different output voltage values. In sleep mode quiescent current is lowered to 30 µA for energy saving; in this mode these LDOs should not be loaded by more than 3-5mA of output current. The innovative design of these general type LDOs reduces the sensitivity to the placement of the output capacitor. These general purpose LDOs do not need the output capacitor to be placed close to the PMU as is the case for normal LDOs. If a (1uF or more) capacitor is attached to a circuit load there is no need to place an output capacitor at the PMU. www.national.com MOMENTARY POWER LOSS When power is removed from the PMU and MPL function is enabled (RTC register 0x1B) then the Momentary Power Loss (MPL) timer starts as unexpected powerdown has occurred. This timer is set to the maximum duration allowed for a momentary power loss (RTC register 0x1B). If power is restored before the timer expires, the MPL block will inform the LP3974 control logic about the MPL event. The MPL circuit is powered from VCOIN pin. MPL timer uses 32.786 kHz RTC crystal oscillator for time base. Host processor needs to enable the MPL function every time the device is powered up. ANALOG SWITCHES Two double pole – double throw switches are integrated on the device and are powered from the VBATT domain. Separate supplies are used for the logic control; LDO9 supplies the power for SW1, and an external supply at VLSW2 supplies the logic on SW2. This arrangement allows some control over the logic thresholds for each switch. These switches are de4 RTC time and alarm registers are user-writable. Alarms registers are used to set periodical or one-time events. The result of an alarm event depends on the PMU state. If the PMU is in standby, then the alarm causes the PMU to start up. If the PMU is in working mode, then the alarm creates an interrupt. INTERRUPTS The LP3974 has 4 main interrupt registers, IRQ1-4. It also has 4 main interrupt masking registers such that if asserted, the particular interrupt that causes an event will be ignored. These interrupts are generated from normal start up / shutdown events, charger events, timed events and warning conditions. OVERVOLTAGE-PROTECTED LDO OUTPUTS (SAFE1/2) SAFE1/2 provide a regulated output of 4.7V from the charger DC input. In this way high voltage protection can be provided for low rated USB devices within the system. As it is derived from the CHGIN pin the operational voltage range for this applies, ie. 4.5V to 7.5V. DEVICE STATUS The LP3974 has 2 status registers and 2 status masking registers. RTC Operational Description This Real Time Clock (RTC) has following features: • Accurate time counting with fine-grained correction for inaccuracies caused by environment • Calendar for years 2000-2099 with leap year compensation and automatic day of week calculation • Two highly customizable alarms All RTC data is presented in Binary Coded Decimal format MASTER RESET The LP3974 has a master reset input which, when brought low, will power down the device for a preset time, then allow the device to power back up. The device will power up with all supplies reset to their default values. 5 www.national.com LP3974 signed for break before make switching, with high speed switching for rail to rail signals. These devices operate over the entire supply range with a flat response for On-Resistance. The switches are bi-directional and hence the pins NC, NO, and COM can be used as inputs or outputs. An input voltage supply of 1.5V to VBATT may be applied at VLSW2 pin to enable SW2 to operate at lower input logic thresholds. LP3974 Physical Dimensions inches (millimeters) unless otherwise noted Micro SMDxt 100 Package NS Package Number RMD100AAA X1 = 4.015mm ± 0.030mm X2 = 4.015mm ± 0.030mm X3 = 0.650mm ± 0.075mm www.national.com 6 LP3974 Notes 7 www.national.com LP3974 PRODUCT BRIEF Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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