LP3921 Datasheet, PDF (5/34 Pages) National Semiconductor (TI) – Battery Charger Management and Regulator Unit with Integrated Boomer® Audio Amplifier

Device Description
The LP3921 Charge Management and Regulator Unit is de-
signed to supply charger and voltage output capabilities for
mobile systems, e.g. CDMA handsets. The device provides a
Li-Ion charging function and 7 regulated outputs. Communi-
cation with the device is via an I²C compatible serial interface
that allows function control and status read-back.
The battery charge management section provides a pro-
grammable CC/CV linear charge capability. Following a nor-
mal charge cycle a maintenance mode keeps battery voltage
between programmable levels. Power levels are thermally
regulated to obtain optimum charge levels over the ambient
temperature range.
CHARGER FEATURES
• Pre-charge, CC, CV and Maintenance modes
• USB Charge 100 mA/450 mA
• Integrated FET
• Integrated Reverse Current Blocking Diode
• Integrated Sense Resistor
• Thermal regulation
• Charge Current Monitor Output
• Programmable charge current 50 mA - 950 mA with 50 mA
steps
• Default CC mode current 100 mA
• Pre-charge current fixed 50 mA
• Termination voltage 4.1V, 4.2V (default), 4.3V, and 4.4V,
accuracy better than +/- 0.35% (typ.)
• Restart level 100 mV, 150 mV (default) and 200 mV below
Termination voltage
• Programmable End of Charge 0.1C (default), 0.15C, 0.2C
and 0.25C
• Enable Control Input
• Safety timer
• Input voltage operating range 4.5V - 6.0V
REGULATORS
Seven low-dropout linear regulators provide programmable
voltage outputs with current capabilities of 80 mA, 150 mA
and 300 mA as given in the table below. LDO1, LDO2 and
LDO3 are powered up by default with LDO1 reaching regu-
lation before LDO2 and LDO3 are started. LDO1, LDO3 and
LDO7 can be disabled/enabled via the serial interface. LDO1
and LDO2, if enabled, must be in regulation for the device to
power up and remain powered. LDO4, LDO5 and LDO6 have
external enable pins and may power up following LDO2 as
determined by their respective enable. Under voltage lockout
oversees device start up with preset level of 2.85V (typ.).
POWER SUPPLY CONFIGURATIONS
At PMU start up, LDO1, LDO2 and LDO3 are always started
with their default voltages. The start up sequence of the LDO's
is given below.
Startup Sequence
LDO1 -> LDO2 -> LDO3
LDO's with external enable control (LDO4, LDO5, LDO6) start
immediately after LDO2 if enabled by logic high at their re-
spective control inputs.
LDO7 (and LDO1, LDO3) may be programmed to enable/dis-
able once PS_HOLD has been asserted.
DEVICE PROGRAMMABILITY
An I²C compatible Serial Interface is used to communicate
with the device to program a series of registers and also to
read status registers. These internal registers allow control
over LDO outputs and their levels. The charger functions may
also be programmed to alter termination voltage, end of
charge current, charger restart voltage, full rate charge cur-
rent, and also the charging mode.
This device internal logic is powered from LDO2.
TABLE 1. LDO Default Voltages
LDO
1
2
3
4
5
6
7
Function
mA
CORE
300
DIGI
300
ANA
80
TCXO
80
RX
150
TX
150
GP
150
Default Voltage (V)
1.8
3.0
3.0
3.0
3.0
3.0
3.0
Startup Default
ON
ON
ON
OFF
OFF
OFF
OFF
Enable Control
SI
-
SI
TCXO_EN
RX_EN
TX_EN
SI
LDO
1
CORE
2
DIGI
3
ANA
4
TCXO
5
RX
6
TX
7
GP
TABLE 2. LDO Output Voltages Selectable via Serial Interface
mA 1.5 1.8 1.85 2.5 2.6 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 3.2 3.3
300 + + + + + + + + + + + + + + + +
300
+++++++++++++
80
++++++++
80 + + + + + + + + + + + + + + + +
150
++++++++
150
++++++++
150 + + + + + + + + + + + + + + + +
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