UB2016 datasheet(7/13 Pages) UTC

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UB2016

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

7 of 13

www.unisonic.com.tw

QW-R502-869.a

OPERATION(Cont.)

4. Charge Status Indicator (CHRG)

The charge status output has three different states: strong pull-down (~10mA), weak pull-down (~20μA) and high

impedance. The strong pull-down state indicates that the UTC UB2016 is in a charge cycle. Once the charge cycle

has terminated, the pin state is determined by undervoltage lockout conditions. A weak pull-down indicates that VCC

meets the UVLO conditions and the UTC UB2016 is ready to charge. High impedance indicates that the UTC

UB2016

is in undervoltage lockout mode: either VCC is less than 100mV above the BAT pin voltage or insufficient

voltage is applied to the VCC pin.

5. Thermal Limiting

An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise

above a preset value of approximately 120°С. This feature protects the UTC UB2016 from excessive temperature

and allows the user to push the limits of the power handling capability of a given circuit board without risk of

damaging the UTC UB2016. The charge current can be set according to typical (not worst-case) ambient

temperature with the assurance that the charger will automatically reduce the current in worst-case conditions.

6. Undervoltage Lockout (UVLO)

An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until

VCC rises above the undervoltage lockout threshold. The UVLO circuit has a built-in hysteresis of 120mV.

Furthermore, to protect against reverse current in the power MOSFET, the UVLO circuit keeps the charger in

shutdown mode if VCC falls to within 30mV of the battery voltage. If the UVLO comparator is tripped, the charger will

not come out of shutdown mode until VCC rise 100mV above the battery voltage.

UB2016 데이터시트(PDF) 7 Page - Unisonic Technologies