PT8A2803 Datasheet, PDF (4/8 Pages) Pericom Semiconductor Corporation – 500mA Li-ion/Polymer Battery Charger

PT8A2803
500mA Li-ion/Polymer Battery Charger
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BAT pin
Always connect the BAT pin to a single-cell Li-ion/Polymer
battery in parallel with a 1µF (or larger) X5R ceramic
capacitor for decoupling and guaranteeing system stability.
When the EN pin is pulled to logic HIGH, the BAT output is
disabled. The PT8A2803 relies on a battery for stability and is
not guaranteed to be stable if the battery is not connected.
Dropout Voltage
When the input voltage is low while the battery voltage is high,
the charging current may not be maintained according to the
equation I_MIN (mA) = 4180/R_IMIN due to a limited internal on-
resistance (R_DS(ON)) of the internal pass element. The worst
resistance of the pass FET is about 1.2Ω at the maximum
operating temperature, thus if tested with 500mA current and
4.2V battery voltage, constant current could still be
maintained when the input voltage is below 4.62V.
Thermal Foldback
The bottom big exposed pad in 5DFN package is used for
thermal foldback. For reducing the chip ambient temperature
as much as possible, it is recommended to connect as much
copper as possible to this pad either on the component layer or
other layers through thermal vias. The thermal regulation
function starts to reduce the charge current when the internal
temperature reaches a typical value of 115°C.
V
4.2V
CC
Mode
CV
Mode
Added loading
Battery Voltage
2.55V
A
I_CHG
I_RECHG
I_PRE
I_MIN
Charging Current
CHG
12-03-0002
Charging
(LED ON)
EOC
(LED
OFF)
Recharge
(LED ON)
Figure 2 PT8A2803 Typical Charge Profile
4
PT0324-1
03/06/12