LTC4156IUFD View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC4156IUFD

Dual-Input Power Manager/3.5A LiFePO4 Battery Charger with I2C Control and USB OTG

Linear Technology 

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LTC4156

PIN FUNCTIONS

PROG (Pin 18): Charge Current Program and Monitor Pin. A

resistor from PROG to GND programs the maximum battery

charge rate. The LTC4156 features I2C programmability

enabling software selection of fifteen charge currents

that are inversely proportional to a single user-supplied

programming resistor.

CHGSNS (Pins 19, 20): Battery Charger Current Sense

Pin. An internal current sense resistor between VOUT

and CHGSNS monitors battery charge current. CHGSNS

should be connected to the source of an external P-channel

MOSFET transistor.

VOUT (Pins 21, 22): Output Voltage of the Switching

PowerPath Controller and Input Voltage of the Battery

Charging System. The majority of the portable product

should be powered from VOUT. The LTC4156 will partition

the available power between the external load on VOUT and

the battery charger. Priority is given to the external load

and any extra power is used to charge the battery. An

ideal diode control function from BATSNS to VOUT ensures

that VOUT is powered even if the load exceeds the allotted

power from VBUS or if the VBUS power source is removed.

VOUT should be bypassed with a low impedance multilayer

ceramic capacitor of at least 22µF.

VBUS (Pins 23, 24, 25): Input Voltage for the PowerPath

Step-Down Switching Regulator and Output Voltage for

the USB On-The-Go Step-Up Switching Regulator. VBUS

may be connected to the USB port of a computer or a DC

output wall adapter or to one or both optional overvolt-

age protection/multiplexer compound transistors. VBUS

should be bypassed with a low impedance multilayer

ceramic capacitor.

SW (Pins 26, 27): Switching Regulator Power Transmis-

sion Pin. The SW pin delivers power from VBUS to VOUT

via the step-down switching regulator and from VOUT to

VBUS via the step-up switching regulator. A 1μH inductor

should be connected from SW to VOUT. See the Applica-

tions Information section for a discussion of current rating.

SCL (Pin 28): Clock Input for the I2C Serial Port. The

I2C input levels are scaled with respect to DVCC for I2C

compliance.

GND (Exposed Pad Pin 29): The exposed pad must be

soldered to the PCB to provide a low electrical and ther-

mal impedance connection to the printed circuit board’s

ground. A continuous ground plane on the second layer of

a multilayer printed circuit board is strongly recommended.

4156f

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