LTC4091 datasheet(8/26 Pages) LINER

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LTC4091

4091fa

For more information www.linear.com/LTC4091

Charge time is increased if charge current is reduced due

to thermal regulation.

Shorting the TIMER pin to GND disables the battery

charging functions.

HVOUT (Pin 18): Voltage Output of the Switching Reg-

ulator. When sufficient voltage is present at HVOUT, the

HVPR pin will be pulled low to indicate that the primary

input has been detected. The LTC4091 switching regula-

tor will maintain just enough differential voltage between

HVOUT and BAT to keep the battery charger MOSFET out

of dropout (typically 100mV from OUT to BAT). HVOUT

should be bypassed with 3.3µF to GND.

BOOST (Pin 19): This pin is used to provide drive voltage,

higher than the input voltage, to the internal bipolar NPN

power switch. Place a 0.22µF to 1µF capacitor between

BOOST and SW as close as possible to the IC. See Appli-

cations section for more information.

SW (Pin 20): The SW pin is the output of the internal high

voltage power switch. Connect this pin to the inductor,

catch diode and a boost capacitor.

VIN (Pin 21): Switching Regulator Input. The VIN pin sup-

plies current to the internal high voltage regulator and to

the internal high voltage power switch. This pin must be

locally bypassed. See Applications Information section to

determine value.

RUN/SS(Pin22):HighVoltageRegulatorEnableInput.The

RUN/SS pin is used to enable the high voltage regulator.

Tie to ground to disable the high voltage input or tie to at

least 3V to enable the high voltage path. If this feature is

not used tie to the VIN pin. This pin can also be used to

soft-start the high voltage regulator; see the Applications

Information section for more information.

GND(ExposedPadPin23):Ground.Theexposedpackage

pad is ground and must be soldered to the PC board for

proper functionality and for maximum heat transfer (use

several vias directly under the LTC4091).

PIN FUNCTIONS

LTC4091 Datasheet(PDF) 8 Page - Linear Technology