SC820 Datasheet, PDF (1/21 Pages) Semtech Corporation – Adapter/USB Dual Input Single-cell Li-ion Charger

POWER MANAGEMENT
Features
„ Dual input charger automatically selects adapter
input over USB
„ Constant voltage — 4.2V, 1% regulation
„ Fast-charge current regulation — 15% at 70mA,
9% at 700mA
„ Three mode charging (current regulation, voltage
regulation, thermal limiting)
„ Input voltage protection — 30V
„ Current-limited adapter charging support — reduces
power dissipation in charger
„ USB input limits charge current to prevent Vbus
overload
„ Instantaneous CC-to-CV transition for faster charging
„ Programmable battery-dependent currents (adapter-
sourced fast-charge & pre-charge, termination)
„ Programmable source-limited currents (USB-sourced
fast-charge & pre-charge)
„ Three termination options — float-charge, automatic
re-charge, or forced re-charge to keep the battery
topped-off after termination without float-charging
„ Soft-start reduces adapter or USB load transients
„ High operating voltage range permits use of
unregulated adapters
„ Complies with CCSA YD/T 1591-2006
„ Space saving 2x2x0.6 (mm) MLPD package
„ WEEE and RoHS compliant
Applications
„ Mobile phones
„ MP3 players
„ GPS handheld receivers
SC820
Adapter/USB Dual Input
Single-cell Li-ion Charger
Description
The SC820 is a dual input (adapter/USB) linear single-cell
Li-ion battery charger in an 8 lead 2x2 MLPD ultra-thin
package. Both inputs will survive sustained input voltage
up to 30V to protect against hot plug overshoot and faulty
charging adapters.
Charging begins automatically when a valid input source
is applied to either input. The adapter input is selected
when both input sources are present.
Thermal limiting protects the SC820 from excessive power
dissipation when charging from either source. The SC820
can be programmed to turn off when charging is complete
or to continue operating as an LDO regulator while float-
charging the battery.
The adapter input charges with an adapter operating in
voltage regulation or in current limit to obtain the lowest
possible power dissipation by pulling the VAD input
voltage down to the battery voltage. The VUSB input
automatically limits load current to prevent over-loading
the USB Vbus supply.
Charge current programming requires two resistors. One
determines battery-capacity dependent currents: adapter
input fast-charge current, pre-charge current, and charge
termination current. The other independently determines
input-limited USB charging currents: USB input fast-
charge and pre-charge current.
Typical Application Circuit
V_ADAPTER
USB Vbus
2.2 μF
2.2 μF
SC820
VAD
VUSB
STATB
GND
ENB
BAT
IPRGM
IPUSB
2.2 μF
Battery Device
Pack
Load
February 26, 2008
© 2008 Semtech Corporation
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