MB39A119 Datasheet, PDF (16/53 Pages) Fujitsu Component Limited. – DC/DC Converter IC of Synchronous Rectification for charging Li-ion battery

MB39A119
and turns off on the synchronous rectification side output transistor, during the interval in which the triangular
wave voltage is lower than the error amplifier output voltage.
(9) Output block (Drv-1, 2)
The output circuit uses a CMOS configuration capable of driving an external N-ch MOS FET both main side and
synchronous rectification side.
(10) Control block (CTL)
Setting the CTL terminal (pin 21) “L” level places in the standby mode.
CTL function table
CTL
Power
OUTD
L
OFF (Standby)
Hi-Z
H
ON (Active)
L
(11) Bias voltage block (VB)
Bias voltage block outputs 5 V (Typ) for the power supply of the output circuit and for setting the bootstrap voltage.
(12) Off time control block (Off time Control)
When MB39A119 operates by high on-duty, voltage difference of both ends of boot strap capacitor CB is
decreasing gradually. In such the case, off time control block charges with CB by compulsorily generating off
time (0.3 µs Typ) .
(13) Overcurrent detection block (Over Current Det.)
Overcurrent detection block detects the 0.2 V (Typ) or more potential difference between +INC2 terminal (pin
10) and -INC2 terminal (pin 11) . When excessive current flows to the charge direction due to load-sudden
change, it determines the overcurrent, makes CS terminal (pin 17) “L” level, and makes the on duty 0 %. After
finishing the overcurrent, MB39A119 restarts with the soft-start operation.
(14) Synchronous rectification control block (Synchronous Cnt.)
CS terminal (pin 17) and 2.6 V (Typ) are compared. Output OUT-2 terminal (pin 24) for synchronous rectification
side FET drive in the soft-start is fixed at “L” level.
Output OUTC2 terminal of current detection amplifier block (Current Amp2) (pin 9) and 0.3 V (Typ) are compared,
and output OUT-2 terminal (pin 24) for synchronous rectification side FET drive is fixed at “L” level at light-load.
16