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FEATURES

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Precision 4.1V Reference (1%)

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High Efficiency Battery Charger Solution

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Average Current Mode Control from

Trickle to Over Charge

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Resistor Programmable Charge Currents

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Internal State Logic Provides Four

Charge States

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Programmable Over Charge Time

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Fully Differential Switch Mode Current

Sensing

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CHG Pin Initiates Charging

Switch Mode Lithium-Ion Battery Charger Controller

BLOCK DIAGRAM

UDG-96197-1

UCC2956

UCC3956

PRELIMINARY

DESCRIPTION

The UCC3956 family of Switch Mode Lithium-Ion Battery Charger

Controllers accurately control lithium-ion battery charging with a

highly efficient average current control loop. This chip is designed to

work as a stand alone charger controller for a single cell or multiple

cell battery pack. This chip combines charge state logic and aver-

age current PWM control circuitry with a 14 bit counter to program

the over charge time. The charge state logic indicates current or

voltage control depending on the charge state. The chip includes

undervoltage lockout circuitry to insure sufficient supply voltage is

present before output switching starts. Additional circuit blocks in-

clude a differential current sense amplifier, a 1% voltage reference,

voltage and current error amplifiers, PWM latch, charge state de-

code bits, and a 500mA output driver.