LP3921 Datasheet, PDF (5/41 Pages) National Semiconductor (TI) – Battery Charger Management and Regulator Unit with Integrated Boomer® Audio Amplifier

LP3921
www.ti.com
SNVS580A – AUGUST 2008 – REVISED MAY 2013
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 regulation 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 respective control inputs.
LDO7 (and LDO1, LDO3) may be programmed to enable/disable 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 current, and also the charging mode.
This device internal logic is powered from LDO2.
LDO
1
2
3
4
5
6
7
Function
CORE
DIGI
ANA
TCXO
RX
TX
GP
Table 1. LDO Default Voltages
mA
Default Voltage (V)
Startup Default
300
1.8
ON
300
3.0
ON
80
3.0
ON
80
3.0
OFF
150
3.0
OFF
150
3.0
OFF
150
3.0
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 + +
+
+++++++++++++
Pin#
1
2
3
Name
LDO6
TX_EN
LDO5
Type ⁽¹⁾
A
DI
A
LP3921 Pin Descriptions⁽¹⁾
Description
LDO6 Output (TX)
Enable control for LDO6 (TX). HIGH = Enable, LOW = Disable
A LDO5 Output (RX)
(1) Key: A=Analog; D=Digital; I=Input; DI/O=Digital-Input/Output; G=Ground; O=Output; P=Power
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