UB2016 Datasheet, PDF (7/13 Pages) Unisonic Technologies – ONE-CELL STANDALONE LINEAR LITHIUM BATTERY CHARGER

UB2016
Preliminary
CMOS IC
„ 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 V_CC
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 V_CC is less than 100mV above the BAT pin voltage or insufficient
voltage is applied to the V_CC 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
V_CC 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 V_CC falls to within 30mV of the battery voltage. If the UVLO comparator is tripped, the charger will
not come out of shutdown mode until V_CC rise 100mV above the battery voltage.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
7 of 13
QW-R502-869.a