ltc4096 Linear Technology Corporation, ltc4096 Datasheet - Page 9

• Manufacturer Part Number: ltc4096
• Description: Dual Input Standalone Li-ion Battery Chargers
• Manufacturer: Linear Technology Corporation

OPERATION
The LTC4096 is designed to effi ciently manage charging a
single-cell lithium-ion battery from two separate voltage
sources: a wall adapter and USB power bus. Using the
constant-current/constant-voltage algorithm, the charger
can deliver up to 1.2A of charge current from the wall
adapter supply or up to 1A of charge current from the
USB supply with a fi nal fl oat voltage accuracy of ±0.6%.
The LTC4096 has two internal P-channel power MOSFETs,
thermal regulation and shut down circuitry. No blocking
diodes or external sense resistors are required.
Power Source Selection
The LTC4096 can charge a battery from either the wall
adapter input or the USB port input. The LTC4096 automati-
cally senses the presence of voltage at each input. If both
voltage sources are present, the LTC4096 defaults to the
wall adapter source provided suffi cient voltage is present
at the DCIN input. “Suffi cient voltage” is defi ned as:
The power present output pin (PWR) indicates that suf-
fi cient input voltage is available. Table 1 describes the
behavior of this status output.
• Supply voltage is greater than the UVLO threshold.
• Supply voltage is greater than the battery voltage by
30mV (100mV or 150mV rising, 30mV falling).
Table 1. Power Source Selection
V
V
V
V
DCIN
DCIN
DCIN
DCIN
> 4.2V and
> BAT + 30mV
< 4.2V or
< BAT + 30mV
V
V
Charger powered from wall adapter source;
V
USBIN current < 25µA
Charger powered from USB source;
V
USBIN
USBIN
PWR
PWR
= V
= V
> 4V and
> BAT + 30mV
DCIN
USBIN
– R
– R
DC-PWR
USB-PWR
Programming and Monitoring Charge Current
The charge current delivered to the battery from the wall
adapter supply is programmed using a single resistor from
the IDC pin to ground.
Similarly, the charge current from the USB supply is
programmed using a single resistor from the IUSB pin
to ground.
Charge current out of the BAT pin can be determined at
any time by monitoring the IDC or IUSB pin voltage and
applying the following equations:
• I
PWR
• I
I
I
R
R
BAT
BAT
PWR
IDC
IUSB
=
=
=
=
R
R
V
V
I
CHRG DC
IDC
IUSB
IDC
IUSB
1000
I
CHRG USB
1000
•
V
V
Charger powered from wall adapter source
V
No charging
PWR: Hi-Z
(
•
USBIN
USBIN
PWR
1000
(
V
LTC4096/LTC4096X
1000
)
V
,
= V
< 4V or
< BAT + 30mV
)
I
CHRG DC
, ( arg
,
DCIN
, ( arg
I
ch
CHRG USB
ch
– R
(
DC-PWR
(
)
ing from wall adapter
ing from USB
=
)
1000
• I
R
=
PWR
IDC
1000
R
V
IUS
B B
V
sup
p
l l y)
4096xf
) )
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