LTC3557EUF-1#TRPBF Linear Technology, LTC3557EUF-1#TRPBF Datasheet - Page 10

• Manufacturer Part Number: LTC3557EUF-1#TRPBF
• Description: IC USB POWER MANAGE 28-QFN
• Manufacturer: Linear Technology

Specifications of LTC3557EUF-1#TRPBF

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

LTC3557/LTC3557-1
PIN FUNCTIONS
V
lators 2 and 3. This pin will generally be connected to V
SW3 (Pin 17): Power Transmission (Switch) Pin for
Step-Down Switching Regulator 3.
V
this pin to the NTC pin will bias the NTC thermistor.
NTC (Pin 19): The NTC pin connects to a battery’s thermistor
to determine if the battery is too hot or too cold to charge. If
the battery’s temperature is out of range, charging is paused
until it drops back into range. A low drift bias resistor is
required from V
NTC to ground. If the NTC function is not desired, the NTC
pin should be grounded.
PROG (Pin 20): Charge Current Program and Charge
Current Monitor Pin. Connecting a resistor from PROG to
ground programs the charge current:
If suffi cient input power is available in constant current
mode, this pin servos to 1V. The voltage on this pin always
represents the actual charge current.
GATE (Pin 21): Ideal Diode Gate Connection. This pin
controls the gate of an optional external P-channel MOSFET
transistor used to supplement the internal ideal diode. The
source of the P-channel MOSFET should be connected
to V
important to maintain high impedance on this pin and
minimize all leakage paths.
BAT (Pin 22): Single Cell Li-Ion Battery Pin. Depending on
available power and load, a Li-Ion battery on BAT will either
deliver system power to V
charged from the battery charger.
V
and Input Voltage of the Battery Charger. The majority of
the portable product should be powered from V
LTC3557/LTC3557-1 will partition the available power
between the external load on V
charger. Priority is given to the external load and any extra
power is used to charge the battery. An ideal diode from
BAT to V
10
IN2
NTC
OUT
I
CHG
OUT
(Pin 16): Power Input for Step-Down Switching Regu-
(Pin 18): Output Bias Voltage for NTC. A resistor from
(Pin 23): Output Voltage of the PowerPath Controller
(A) =
and the drain should be connected to BAT. It is
OUT
ensures that V
1000V
R
NTC
PROG
to NTC and a thermistor is required from
OUT
OUT
through the ideal diode or be
OUT
is powered even if the load
and the internal battery
OUT
. The
OUT
.
exceeds the allotted input current from V
power source is removed. V
a low impedance multilayer ceramic capacitor. The total
capacitance on V
over operating voltage and temperature.
V
connected to the USB port of a computer or a DC output wall
adapter. V
multilayer ceramic capacitor.
ACPR (Pin 25): Wall Adapter Present Output (Active
Low). A low on this pin indicates that the wall adapter
input comparator has had its input pulled above its input
threshold (typically 4.3V). This pin can be used to drive the
gate of an external P-channel MOSFET to provide power to
V
V
pin can be used to drive the V
high voltage buck switching regulator. An external P-channel
MOSFET is required to provide power to V
tied to the ACPR pin. The V
LT
CLPROG (Pin 27): Input Current Program and Input Current
Monitor Pin. A resistor from CLPROG to ground determines
the upper limit of the current drawn from the V
(i.e., the input current limit). A precise fraction of the input
current, h
PowerPath delivers current until the CLPROG pin reaches
2.0V (10x Mode), 1.0V (5x Mode) or 0.2V (1x Mode).
Therefore, the current drawn from V
amount given by h
the resistor R
CHRG (Pin 28): Open-Drain Charge Status Output. The
CHRG pin indicates the status of the battery charger.
Four possible states are represented by CHRG: charging,
not charging (i.e., fl oat charge current less than 1/10th
programmed charge current), unresponsive battery (i.e., its
voltage remains below 2.8V after 1/2 hour of charging) and
battery temperature out of range. CHRG requires a pull-up
resistor and/or LED to provide indication.
Exposed Pad (Pin 29): Ground. The exposed package pad
is ground and must be soldered to the PC board for proper
functionality and for maximum heat transfer.
BUS
OUT
C
®
(Pin 26): High Voltage Buck Regulator Control Pin. This
3480, LT3481 and LT3505.
from a power source other than a USB port.
(Pin 24): USB Input Voltage. V
BUS
CLPROG
CLPROG
should be bypassed with a low impedance
OUT
, is sent to the CLPROG pin. The input
CLPROG
should be set to no less than 2.1k.
should maintain a minimum of 5μF
and R
C
pin is designed to work with the
OUT
C
pin of an approved external
CLPROG
should be bypassed with
BUS
. In USB applications
BUS
will be limited to an
BUS
OUT
will usually be
or if the V
with its gate
BUS
35571fc
BUS
pin