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www.semtech.com
SC805
Miniature Integrated High Current
Lithium-Ion Battery Charger
POWER MANAGEMENT
Final
C 1
1 uF
B A TTE R Y
R 7
1 k
S C 80 5
1
7
9
4
5
1 0
2
8
3
6
V C C
E N /N TC
R TI M E
I P R G M
I TE R M
C H R G B
V C C IL
N O B A T
V O U T
G N D
R 4
3 .0 1k
t
R T1
The rm is t o r
D 2
L E D
C 1
2 .2 uF
Charging
Indicator
D 3
L E D
R 5
3 .0 1k
R 2
3 .0 1k
R 1
3 .0 1k
SC805 typical Application Circuit
D 1
L E D
C H A R G E R V I N
R 3
3 .0 1k
Adapter
Present
Indicator
Charge
Complete
Indicator
R 6
1 k
Revision 4, March 2004
Description
Features
Applications
Typical Application Circuit
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Fully integrated charger with FET pass transistor,
reverse-blocking diode, sense resistor and thermal
protection
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High Accuracy Charge Current*
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Tiny 3mm x 3mm 10 lead MLP package
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Programmable precharge, fastcharge & termination
current
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Battery voltage controlled to 1% accuracy
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Built in timer for protection and complete charging
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NTC interface with battery detection
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Soft-start for step load and adaptor plug-in
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Up to 1A continuous charge current
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Input voltage range from 3V to 6V allows seamless
charging from current limited adapter
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Provides buffered adapter voltage VCCIL to power
external accessories
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Battery Present detection and output indicator
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Operates in charger or LDO-mode without battery
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0.1
A battery drain current in shutdown and
monitor modes
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Over current protection in all charging modes
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CHRGB output communicates charging and end of
charge cycle
*Patent Pending
The SC805 is a fully integrated, single cell, constant-cur-
rent (cc)/constant-voltage (cv) Lithium-Ion battery charger
in a tiny 3x3 mm thermally enhanced lead free MLP pack-
age. The SC805 can operate as a stand-alone charger or
in conjunction with a Power Management Controller
(PMIC).
The SC805 has a pre-charge function for trickle charging
deeply discharged batteries. The fast charge current is
enabled automatically when the battery voltage reaches
the required threshold. When the battery reaches the
constant voltage or CV portion of the charge curve the
SC805 switches to CV regulation mode. In this mode
the output current decays until the termination current is
reached. At this point the SC805 signals the charge cycle
is complete. The charger can be configured to continue
charging for a predetermined time or turn off when the
termination current is reached. After the charger turns
off the output device, the SC805 enters monitor mode.
If the battery voltage drops by 100mV from the CV volt-
age a new charge cycle will begin. The timer function
also protects against charging faulty batteries by turning
off if the pre-charge time exceeds 1/4 of the total pro-
grammed charge duration.
The SC805 also provides battery detection, NTC inter-
face, and a buffered output for driving system loads from
the adapter input supply.
The SC805 can also function as a general purpose cur-
rent source or as a current source for charging nickel-
cadmium (NiCd) and nickel-metal-hydride (NiMH) batter-
ies.
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Cellular phones
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PDAs
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Handheld meters
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Charging stations
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USB chargers
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Digital cameras
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Programmable current source