Datasheet
9
LTC4011
4011fa
V
CDIV
(Pin 9): Average Cell Voltage Resistor Divider Ter-
mination. The LTC4011 connects this pin to GND provided
the charger is not in shutdown. V
CDIV
is an open-drain
output to GND with an operating voltage range of GND to
BAT.
TIMER (Pin 10): Charge Timer Input. A resistor connected
between TIMER and GND programs charge cycle timing
limits. Refer to the Applications Information section for
complete details. Operating voltage range is GND to 1V.
SENSE (Pin 11): Charge Current Sense Input. An external
resistor between this input and BAT is used to program
charge current. Refer to the Applications Information
section for complete details on programming charge
current. Operating voltage ranges from (BAT – 50mV) to
(BAT + 200mV).
BAT (Pin 12): Battery Pack Connection. The LTC4011 uses
the voltage on this pin to control current sourced from V
CC
to the battery during charging. Allowable operating volt-
age range is GND to V
CC
.
TOC (Pin 13): Active-Low Top-Off Charge Indicator Out-
put. The LTC4011 indicates the top-off charge state for
NiMH batteries by connecting this pin to GND. Refer to the
Operation and Applications Information sections for fur-
ther details. This output is capable of driving an LED and
should be left floating if not used. TOC is an open-drain
output to GND with an operating voltage range of GND to
V
CC
.
INTV
DD
(Pin 14): Internal 5V Regulator Output. This pin
provides a means of bypassing the internal 5V regulator
used to power the BGATE output driver. Typically, power
should not be drawn from this pin by the application
circuit. Refer to the Application Information section for
additional details.
BGATE (Pin 15): External Synchronous N-channel MOSFET
Gate Control Output. This output provides gate drive to an
optional external NMOS power transistor switch used for
synchronous rectification to increase efficiency in the
step-down DC/DC converter. Operating voltage is GND to
INTV
DD
. BGATE should be left floating if not used.
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PGND (Pin 16): Power Ground. This pin provides a return
for switching currents generated by internal LTC4011
circuits. Externally, PGND and GND should be wired
together using a very low impedance connection. Refer to
PCB Layout Considerations in the Applications Informa-
tion section for additional grounding details.
TGATE (Pin 17): External P-channel MOSFET Gate Control
Output. This output provides gate drive to an external
PMOS power transistor switch used in the DC/DC con-
verter. Operating voltage range varies as a function of V
CC
.
Refer to the Electrical Characteristics table for specific
voltages.
V
CC
(Pin 18): Power Input. External PowerPath control
circuits normally connect either the DC input power supply
or the battery to this pin. Refer to the Applications Infor-
mation section for further details. Suggested applied
voltage range is GND to 34V.
READY (Pin 19): Active-Low Ready-to-Charge Output.
The LTC4011 connects this pin to GND if proper operating
voltages for charging are present. Refer to the Operation
section for complete details on charge qualification. This
output is capable of driving an LED and should be left
floating if not used. READY is an open-drain output to GND
with an operating voltage range of GND to V
CC
.
INFET (Pin 20): PowerPath Control Output. For very low
dropout applications, this output may be used to drive the
gate of an input PMOS pass transistor connected between
the DC input (DCIN) and the raw system supply rail (V
CC
).
INFET is internally clamped about 6V below V
CC
. Maxi-
mum operating voltage is V
CC
. INFET should be left
floating if not used.
Exposed Pad (Pin 21): This pin provides enhanced
thermal properties for the TSSOP. It must be soldered to
the PCB copper ground to obtain optimum thermal
performance.