MB39A214APFT-G-JNERE1 Datasheet, PDF (15/56 Pages) Fujitsu Component Limited. – 2ch DC/DC converter IC with PFM/ PWM synchronous rectification

MB39A214A
(4) Starting sequence
When the EN1 pin (pin 2) or EN2 pin (pin 11) is set to the “H” level, the bias voltage is supplied from the
VB pin. If the voltage of the VB pin exceeds the UVLO threshold voltage, the DC/DC converter starts
operations and carries out the soft start. The soft start is a function used to prevent a rush current when the
power is started.
Activating the soft start initiates charging of the capacitor connected to the CS1 pin (pin 5) and CS2 pin (pin
8) and inputs the lamp voltage to the error comparator (Error Comp.) of each channel. The DC/DC
converter generates the output voltage according to that lamp voltage. This results in the soft start operation
that does not depend on the output load. The over voltage protection (OVP) and under voltage protection
(UVP) functions are disabled while the soft start is active.
<Timing chart>
EN1
VB
CS1
DRVH1
DRVL1
VOUT1
EN2
CS2
DRVH2
DRVL2
VOUT2
UVLO release
UVLO VTLH
CH1 soft start completed
0.805 V
INTREF
1.6 V
CH2 soft start completed
INTREF
1.6 V
0.805 V
DS405-00007-1v0-E
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