MB3885PFV FUJITSU [Fujitsu Component Limited.], MB3885PFV Datasheet - Page 17

• Manufacturer Part Number: MB3885PFV
• Description: 1-channel DC/DC Converter IC with Synchronous Rectifier
• Manufacturer: FUJITSU [Fujitsu Component Limited.]

SOFT START TIME SETTING
The soft start function prevents rush current events when the IC power is turned on, by connecting soft start
capacitors (Cs) to the CS terminal (pin 6) .
When the IC is activated (Vcc
externally connected soft start capacitors (Cs) at 10 A.
Because the error Amp. output (FB) is determined by the ratio of the lower of the two non-inverted input terminals
(1.25 V, CS terminal voltage) to the inverted input terminal voltage ( INE) , the soft start interval (when CS
terminal voltage
Thus the DC/DC converter output voltage is in proportion to the rise in the CS terminal voltage as the soft start
capacitor connected to the CS terminal charges. The soft start time is determined by the following formula.
Soft start time (time to output 100 )
ts (s) : = 0.125
1.25 V
2.3 V
0 V
Cs ( F)
1.25 V) FB is determined by the ratio of the INE terminal voltage and CS terminal voltage.
Soft start time ts
UVLO threshold voltage) , Q2 is off and the CS terminals begin charging the
CS terminal voltage
Error. amp block comparison voltage
to
INE voltage
MB3885
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