MB39A132QN-G-ERE1 Datasheet, PDF (27/56 Pages) Fujitsu Component Limited. – ASSP For Power Management Applications (Rechargeable Battery) Synchronous Rectification DC/DC Converter IC for Charging Li-ion Battery

MB39A132
■ TRANSIT RESPONSE AT STEP LOAD CHANGE
The constant voltage control loop and the constant current control loop are independent of each other .
When a load changes suddenly, a control loop is replaced by the other.
Overshoot of the battery voltage and current is generated by the delay occurring in a control loop at a mode
change.
The delay time is determined by the phase compensation components values.
When the constant current control changes to the constant voltage control after the battery is removed, the
control period with higher duty than the setting charge voltage occurs, resulting in a voltage overshoot.
However, since the battery is removed, no excessive voltage is to be applied to the battery.
When the constant voltage control changes to the constant current control after the battery is inserted, the
control period with higher duty than the rated charge current occurs, resulting in current overshoot.
In MB39A132, a current overshoot lasting less than 10 ms is not deemed to be a current overshoot.
Error Amp3 output
Error Amp2 output
Error Amp2 output
Constant current
Error Amp3 output
Constant voltage
Constant current
Battery voltage
Battery current
When the charge control switches
from the constant current control to
the constant voltage control, the
control period with higher duty than
the rated charge voltage occurs,
resulting in a voltage overshoot.
10 ms
In MB39A132, a current overshoot
lasting less than 10 ms is not
deemed to be a current overshoot.
DS04–27265–3E
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