LTC4055 Linear Technology, LTC4055 Datasheet - Page 8

• Manufacturer Part Number: LTC4055
• Description: USB Power Controller and Li-Ion Linear Charger
• Manufacturer: Linear Technology

PI FU CTIO S
LTC4055
BAT (Pin 2): Connect to a single cell Li-Ion battery. Used
as an output when charging the battery and as an input
when supplying power to OUT. When the OUT pin potential
drops below the BAT pin potential, an ideal diode function
connects BAT to OUT and prevents V
more than 100mV below V
tor divider sets the final float potential on this pin. The
internal resistor divider is disconnected when IN1/IN2 and
OUT are in UVLO.
OUT (Pin 3): Voltage Output. Used to provide controlled
power to a USB device from either USB V
the battery (BAT) when the USB is not present. Can also be
used as an input for battery charging when the USB is not
present and a wall adaptor is applied to this pin. Should be
bypassed with at least 10 F to GND.
IN1/IN2 (Pin 4/Pin 1): Input Supply. Connect to USB
supply, V
USB V
current is limited to either 20% or 100% of the current
programmed by the CLPROG pin as determined by the
state of the HPWR pin. Charge current (to BAT pin)
supplied through the inputs is set to the current pro-
grammed by the PROG pin but will be limited by the input
current limit if set greater than the current limit.
Connect IN2 to IN1 with a resistance no greater than
0.05 .
WALL (Pin 5): Wall Adapter Present Input. Pulling this pin
above 1V will disable charging from IN1/IN2 and discon-
nect the power path from IN1/IN2 to OUT. The ACPR pin
will also be pulled low to indicate that a wall adapter has
been detected. Requires the voltage on IN1/IN2 or OUT to
be 100mV greater than V
activate this function.
SHDN (Pin 6): Shutdown Input. Pulling this pin high will
disable the entire part and place it in a low supply current
mode of operation. All power paths will be disabled. A
weak pull-down current is internally applied to this pin to
ensure it is enabled at power up when the input is not being
driven externally.
8
U
BUS
BUS
U
for power control to a USB device. Input
. Used as main supply while connected to
U
BAT
BAT
. A precision internal resis-
and greater than V
OUT
BUS
from dropping
(IN1/IN2) or
UVLO
to
SUSP (Pin 7): Suspend Mode Input. Pulling this pin above
1.2V will disable charging from IN1/IN2 and disconnect
the power path from IN1/IN2 to OUT. The supply current
will be reduced to comply with the USB specification for
Suspend mode. The BAT to OUT ideal diode function will
remain active as well as the ability to charge the battery
from OUT. Suspend mode will reset the charge timer if
V
kept greater than V
present, the charge timer will not be reset when the part is
put in suspend. A weak pull-down current is internally
applied to this pin to ensure it is low at power up when the
input is not being driven externally.
HPWR (Pin 8): High Power Select. Used to control the
amount of current drawn from the USB port. A logic HI on
the pin will set the current limit to 100% of the current
programmed by the CLPROG pin and 100% of the charge
current programmed by the PROG pin. A logic low on the
pin will set the current limit to 20% of the current pro-
grammed by the CLPROG pin and decrease battery charge
current to 16% of the current programmed by the CLPROG
pin. A weak pull-down current is internally applied to this
pin to ensure it is low at power up when the input is not
being driven externally.
CLPROG (Pin 9): Current Limit Program. Connecting a
resistor, R
current limit. The current limit is programmed as follows:
In USB applications the resistor R
no less than 105k.
GND (Pin 10): Ground.
PROG (Pin 11): Charge Current Program. Connecting a
resistor, R
current. The battery charge current is programmed as
follows:
OUT
I
I
CL
CHG
is less than V
( )
A
( )
A
CLPROG
PROG
R
V
R
CLPROG
CLPROG
V
PROG
PROG
, to ground programs the battery charge
to ground, programs the input to output
BAT
BAT
•
•
50 000
while in suspend mode. If V
, such as when a wall adapter is
50 000
,
,
50 000
R
CLPROG
50 000
R
CLPROG
,
PROG
,
V
should be set to
V
OUT
4055p
is