LP3918 Datasheet, PDF (4/39 Pages) National Semiconductor (TI) – Battery Charge Management and Regulator Unit

LP3918
SNVS476D – AUGUST 2007 – REVISED MAY 2013
www.ti.com
• Thermal regulation
• Charge Current Monitor Output
• Programmable charge current 50mA - 950mA with 50mA steps
• Default CC mode current 100mA
• Pre-charge current fixed 50mA
• Termination voltage 4.1V, 4.2V (default), 4.3V, and 4.4V, accuracy better than +/- 0.5% (typ)
• Restart level 50mV, 100mV, 150mV (default) and 200mV below Termination voltage
• End of Charge 0.1C (default), 0.15C, 0.2C and 0.25C
• Programmable Enable Control
• Safety timer
• Input voltage operating range 4.5V - 6.0V
• LDO mode on LP3918TL-L option.
REGULATORS
7 Low dropout linear regulators provide programmable voltage outputs with current capabilities of 80mA, 150mA
and 300mA 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. During power up LDO1 and LDO2 must reach their regulation voltage detection point 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 and 3) may be programmed to enable/disable once PS_HOLD has been asserted.
Default voltages for the LDOs are shown in Table 1 and Table 2 shows the voltages that may be programmed
via the Serial Interface.
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
mA
CORE
300
DIGI
300
ANA
80
TCXO
80
RX
150
TX
150
GP
150
Table 1. LDO Default Voltages
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
4
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