LP3974RME/NOPB [TI]
PRODUCT BRIEF High Performance Power Management Unit for Application Processors; 对于应用处理器产品简介高性能电源管理单元
| 型号： | LP3974RME/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | PRODUCT BRIEF High Performance Power Management Unit for Application Processors |
| 文件： | 总10页 (文件大小：1115K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LP3974
LP3974 PRODUCT BRIEF High Performance Power Management Unit for
Application Processors
Literature Number: SNVS645A
October 19, 2011
LP3974
PRODUCT BRIEF
High Performance Power Management Unit for Application
Processors
General Description
Features
The LP3974 is designed to meet the power management re-
quirements 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 regula-
tors, 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 I2C-
compatible high-speed Serial Interface allowing control of
program on/off conditions and the output voltages of individ-
ual regulators, and to read status information of the PMU.
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
It can charge and maintain a single cell Li-Ion battery operat-
ing from an AC adapter or USB power source.
11 General-type Low Noise LDOs
■
7 x 300 mA
2 x 450 mA
2 x 150 mA
The Li-Ion charger requires few external components and in-
tegrates the power FET. Charging is thermally regulated to
obtain the most efficient charging rate for a given ambient
temperature.
5 wide-input low-output (WILO) LDOs
■
2 x 10 mA
1 x 50 mA
2 x 150 mA
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.
All LDOs S/W configurable
■
■
■
■
■
■
■
■
Buck regulators have an automatic switch to ECO mode at
low load conditions providing very good efficiency at low out-
put currents.
Two over-voltage protected outputs for USB transceivers
Real time clock with two alarms
General-type LDO regulators provide excellent PSRR and
ULTRA LOW NOISE, 45 μV typ., ideally suited for supplying
voltage to RF section.
Back-up battery charger
Momentary Power Loss detection
Interrupt Request to reduce S/W polling
I2C-compatible Serial Interface
The real-time clock/calendar provides time interval informa-
tion as well as two programmable alarms.
100-bump 0.4 mm pitch micro SMDxt package
To accommodate different processor requirements, the
LP3974 PMU can have three different default voltage settings
and startup sequences selected by external pin.
Applications
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
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
Typical Application Diagram
30113001
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2
Device Pin Diagram
30113002
TOP VIEW
100–Bump (0.4 mm pitch) micro SMDxt Package
Package Marking Information
30113003
Ordering Information
Order Number
LP3974RME/NOPB
LP3974RMX/NOPB
Production Identification
Supplied as
3974
3974
250 Tape & Reel
1000 Tape & Reel
3
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WILO-Type LDOs
Operational Description
Wide Input Low Output LDOs are designed to enable a low-
ered output voltage range with voltages down to 0.8V.
The LP3974 is designed for the charging and voltage rail re-
quirements within mobile handsets. The linear charger ac-
cepts 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 pro-
vide for distributed power within the handset.
SINGLE INPUT LINEAR CHARGER
LP3974 has a built-in Li-Ion/Li-Poly battery management sys-
tem. 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 volt-
age 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 out-
put 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 in-
puts while Buck2 has DVS capability via SET3 input. Addi-
tional 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 in-
put, 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-of-
charge condition, the charge management isolates the bat-
tery 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 cy-
cle is re-initiated to re-establish the termination voltage level.
LDO INFORMATION
All LDOs can be programmed through serial interface for dif-
ferent output voltage values which are summarized in the
output voltage selection tables below.
BACKUP BATTERY CHARGER
Backup battery charger (BBC) is intended for charging an ex-
ternal 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 pro-
grammable to 5 voltages from 2.9V to 3.3V. The default output
is set to 3.0V.
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 im-
portant 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.
It is possible to turn backup battery charger off via registers.
BBC has a reverse current protection.
General-Type LDOs
MOMENTARY POWER LOSS
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 out-
put voltage values.
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 mo-
mentary 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.
In sleep mode quiescent current is lowered to 30 µA for en-
ergy saving; in this mode these LDOs should not be loaded
by more than 3-5mA of output current.
The MPL circuit is powered from VCOIN pin. MPL timer uses
32.786 kHz RTC crystal oscillator for time base. Host proces-
sor needs to enable the MPL function every time the device
is powered up.
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.
ANALOG SWITCHES
Two double pole – double throw switches are integrated on
the device and are powered from the VBATT domain. Sepa-
rate 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 de-
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4
signed for break before make switching, with high speed
switching for rail to rail signals.
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.
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.
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 / shut-
down events, charger events, timed events and warning con-
ditions.
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 ap-
plies, ie. 4.5V to 7.5V.
DEVICE STATUS
RTC Operational Description
The LP3974 has 2 status registers and 2 status masking reg-
isters.
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
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.
All RTC data is presented in Binary Coded Decimal format
5
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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
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Notes
7
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