UB10803G-SH2-R datasheet(6/10 Pages) UTC

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UB10803

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 10

www.unisonic.com.tw

QW-R502-A26.b



OPERATION(Cont.)

6. IMIN Indication

The IMIN pin can be used to program the End-of-Charge (EOC) current by connecting a resistor between this pin

and the GND pin. The programming is defined by the following equation:

MIN

IMIN

800

I(mA) =

Where RIMIN is usually in kΩ.

7. IREF Pin

The IREF pin is for fast charge-current programming. By connecting a resistor between this pin and the GND pin,

the fast charge current limit is determined by the following equation:

CHG

IREF

4000

I(mA) =

Where RIREF is in kΩ. The actual charge current is guaranteed to have 10% accuracy of ICHG with the charge

current set at 150mA.

8. BAT pin

Always connect the BAT pin to a single-cell Li-ion/Polymer battery in parallel with a 1μF (or larger) X5R ceramic

capacitor for decoupling and guaranteeing system stability. When the EN pin is pulled to logic HIGH, the BAT output

is disabled. The UTC UB10803 relies on a battery for stability and is not guaranteed to be stable if the battery is not

connected.

9. Dropout Voltage

When the input voltage is low while the battery voltage is high, the charging current may not be maintained

according to the equation ICHG (mA) = 4000/RIREF due to a limited internal on-resistance (RDS(ON)) of the internal pass

element. The worst resistance of the pass FET is about 1.2Ω at the maximum operating temperature, thus if tested

with 500mA current and 4.2V battery voltage, constant current could still be maintained when the input voltage is as

low as 4.62V.

10. Thermal Foldback

The bottom big exposed pads in both HSOP-8 and DFN-8(2x3) packages are used for thermal foldback. For

reducing the chip ambient temperature as much as possible, it is recommended to connect as much copper as

possible to this pad either on the component layer or other layers through thermal vias. The thermal regulation

function starts to reduce the charge current when the internal temperature reaches a typical value of 115°C.

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