LTC4099 Linear Technology Corporation, LTC4099 Datasheet - Page 10

• Manufacturer Part Number: LTC4099
• Description: I2C Controlled USB Power Manager/Charger
• Manufacturer: Linear Technology Corporation

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LTC4099
PIN FUNCTIONS
OVGATE (Pin 1): Overvoltage Protection Gate Output.
Connect OVGATE to the gate pin of an external N-channel
MOSFET pass transistor. The source of the transistor should
be connected to V
to the product’s DC input connector. In the absence of an
overvoltage condition, this pin is driven from an internal
charge pump capable of creating suffi cient overdrive to
fully enhance the pass transistor. If an overvoltage condition
is detected, OVGATE is brought rapidly to GND to prevent
damage to the LTC4099. OVGATE works in conjunction
with OVSENS to provide this protection.
NTC (Pin 2): Input to the Negative Temperature Coeffi cient
Thermistor Monitoring Circuit. The NTC pin connects to
a negative temperature coeffi cient thermistor which is
typically copackaged with the battery 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 the
battery temperature re-enters the valid range. A low drift
bias resistor is required from NTCBIAS to NTC and a
thermistor is required from NTC to ground.
NTCBIAS (Pin 3): NTC Thermistor Bias Output. Connect a
bias resistor between NTCBIAS and NTC, and a thermistor
between NTC and GND.
V
Output. This pin drives the V
Technology step-down switching regulator. In conjunction
with WALL and ACPR, it will regulate V
battery charger effi ciency.
WALL (Pin 5): Auxiliary Power Source Sense Input. WALL
is used to determine when power is available from an
auxiliary power source. When power is detected, ACPR is
driven low and the USB input is automatically disabled.
BATSENS (Pin 6): Battery Voltage Sense Input. For proper
operation, this pin must always be connected to BAT. For
best operation, connect BATSENS to BAT physically close
to the Li-Ion cell.
PROG (Pin 7): 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 one of eight possible I
10
C
(Pin 4): Bat-Track Auxiliary Switching Regulator Control
BUS
and the drain should be connected
2
C controllable voltages (see
C
pin of an external Linear
OUT
to maximize
Table 3). The voltage on this pin always represents the
actual charge current by using the following formula:
IRQ (Pin 8): Open-Drain Interrupt Output. The IRQ pin
can be used to generate an interrupt due to a multitude
of maskable status change events within the LTC4099.
See Table 1.
GND (Pin 9): Ground.
IDGATE (Pin 10): Ideal Diode Amplifi er Output. This pin
controls the gate of an external P-channel MOSFET tran-
sistor used to supplement the internal ideal diode. The
source of the P-channel MOSFET should be connected to
V
BAT (Pin 11): 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
diode or be charged from the battery charger.
V
Controller and Input Voltage of the Battery Charger. The
majority of the portable product should be powered from
V
tween 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
exceeds the allotted power from V
source is removed. V
impedance multilayer ceramic capacitor.
V
Controller. V
of a computer or a DC output wall adapter. V
be bypassed with a low impedance multilayer ceramic
capacitor.
SW (Pin 14): Switching Regulator Power Transmission
Pin. The SW pin delivers power from V
step-down switching regulator. An inductor should be con-
nected from SW to V
section for a discussion of inductance value.
OUT
OUT
OUT
BUS
I
BAT
. The LTC4099 will partition the available power be-
(Pin 12): Output Voltage of the Switching PowerPath
(Pin 13): Input Voltage for the Switching PowerPath
and the drain should be connected to BAT.
OUT
R
V
PROG
PROG
BUS
ensures that V
will usually be connected to the USB port
• 1030
OUT
OUT
. See the Applications Information
should be bypassed with a low
OUT
OUT
is powered even if the load
and the internal battery
BUS
OUT
or if the V
BUS
through the ideal
to V
BUS
OUT
BUS
should
via the
power
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