MB3886PFV FUJITSU [Fujitsu Component Limited.], MB3886PFV Datasheet - Page 17

• Manufacturer Part Number: MB3886PFV
• Description: 2-Channel DC/DC Converter IC with Overcurrent Protection Symmetrical-Phase Type
• Manufacturer: FUJITSU [Fujitsu Component Limited.]

SETTING THE OVERCURRENT DETECTION CURRENT
The overcurrent protection circuit is actuated upon completion of the soft-start period. If an overcurrent flows,
the circuit detects the increase in the voltage between the main-side FET’s drain and source by the main-side
FET ON resistor (RON) and sets the latch to fix the main and synchronous rectification outputs of the relevant
channel at the “L” level. At the same time, the circuit fixes the PSIG1 terminal (pin 1) at the “L” level when the
overcurrent is detected on CH1 or the PSIG2 terminal (pin 30) at the “L” level when it is detected on CH2. The
detection current value can be set by the resistors (R
drain and the ILIM1 terminal (pin 3) /ILIM2 terminal (pin 28) , respectively. Note that the overcurrent protection
circuit works for each channel separately.
Detection current value : I
RON : Main-side FET ON resistor, Vin : Input voltage, Vo : DC/DC converter output voltage
f
TREATMENT OF UNUSED ILIM PINS
When the overcurrent protection circuit is not used, the ILIM1 terminal (pin 3) and ILIM2 terminal (pin 28) should
be shorted to the SGND terminal (pin 6) using the shortest possible connection.
OSC
I
OCP
: Oscillation frequency, L : Coil inductance
(A) : =
I
LIM
(A)
Ron ( )
R
LIM
OCP
( )
< Operation Without Using the ILIM Terminals >
2
(Vin (V)
3
6
Vin (V)
ILIM1
SGND
Vo (V) )
f
OSC
LIM1
(Hz)
and R
Vo (V)
L (H)
ILIM2
LIM2
) connected between the main-side FET’s
28
MB3886
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