SC908 Datasheet, PDF (1/30 Pages) Semtech Corporation – Power Management IC for Single-Cell Li-Ion Devices

SC908
POWER MANAGEMENT
Power Management IC for
Single-Cell Li-Ion Devices
Features
„ Single Cell Li-Ion battery charger — CC/CV charging
with current soft start
„ Charger regulated output voltage — 4.2V ±1% over
temperature with Kelvin sense of battery voltage
„ Charger input protection withstands 28V indefinitely
„ Charger max constant current setting — 500mA
„ Adjustable charge termination current down to
10mA
„ Battery NTC interface disables charging if battery
temperature out of range
„ Programmable low battery detector threshold
„ Four status indicators
„ Programmable charge completion timer
„ Buck converter with enable — output programmable
from 1V to 3V, 150mA max output
„ Buck converter efficiency — 88% at 50mA
„ General purpose low noise LDO regulator with fast
enable, active shutdown
„ 4x4x0.9 (mm) MLPQ package
„ WEEE and RoHS compliant
Applications
„ Bluetooth headsets
„ MP3 players
„ Low cost mobile phones
Typical Application Circuit
Description
The SC908 is a complete power management system
designed for use in Bluetooth wireless headsets, portable
media players, and other battery-powered electronics
where size is critical. Included are a full featured stand-
alone Li-Ion battery charger with a programmable
low-battery monitor, a low noise LDO regulator, and a DC-
DC buck converter.
Battery charging features include programmable pre-
charge, fast-charge, and termination current settings.
Charge termination is controlled by a programmable
timer and by a resistor that sets the termination current.
The 28V max input voltage protects against hotplug over-
shoot and faulty adapters without additional protection
circuitry. The battery voltage Kelvin sense input elimi-
nates errors due to high charging currents. A battery
thermistor interface disables charging when the battery
temperature exceeds safe-to-charge limits.
The step-down switching regulator (buck converter)
improves system efficiency and extends battery life. The
LDO regulator can be powered directly from the battery
or from the buck converter output when efficiency is criti-
cal. The fast-starting low noise LDO regulator is suitable
for audio, RF, or general purpose regulation required by
peripheral devices, such as a vibrating alert motor. The
low battery detector warns when the battery level is
below 3.3V, and when the battery has discharged below
a lower programmable voltage limit.
Charging Adapter
CVAD
Charging
Charger
Present
RRLBAT
CVREF
RNPU
CVSYS
RNTC (Battery
Pack NTC
Thermistor)
VAD
VSYS
BAT
BSEN
RTIME
ITERM
IPRGM
EN_NTC
LEN
SC908 ^LVIN
LVOUT
CHRGB
CPB
FLTB
LFB
SEN
SLX
LBATB
RLBAT
VREF
AGND
SFB
DGND
PGND
RRTIME
RITERM
RIPRGM
LS
CSFB
RS1
CSFG
RS2
January 24, 2008
© 2008 Semtech Corporation
CBAT
Li-Ion
BATTERY
CLVIN
Can supply LDO
from battery or from
DC-DC converter
To Audio Circuits
or vibrator motor
SVOUT,
To Bluetooth
Processor
CSVOUT
RL1
CLVOUT
RL2
US Patent: 6,836,095
1