MB39A214APFT-G-JNERE1 Datasheet, PDF (17/56 Pages) Fujitsu Component Limited. – 2ch DC/DC converter IC with PFM/ PWM synchronous rectification

MB39A214A
(7) Over Current Limitation (ILIM)
This function limits the output current when it has increased, and protects devices connected to the output.
This function detects the inductor current I_L from the electromotive force of the low-side FET on-resistance
R_ON, and compares this voltage with the 1/5-time value of the voltage V_ILIM of the ILIM1 pin (pin 20) and
ILIM2 pin (pin 16) on a cyclically, using ILIM Comp. Until this voltage falls below the over current limit
value, the high-side FET is held in the off state. After the voltage has fallen below the limit value, the
high-side FET is placed into the on state. This limits the lower bound of the inductor current and also
restricts the over current. As a result, it becomes operation that the output voltage droops.
The over current limit value is set by connecting the resistor to the ILIM pin. The ILIM pin supplies the
constant current of 5 µA (Typ) . However, the current value has a temperature slope up to 4500 ppm/°C to
compensate the temperature dependence characteristics of the low-side FET on-resistance.
IL
(IOUT1
)
VOUT
DRVH
DRVL
Normal operation
ILIM detection value (RON × IL = ^VILIM )
5
Keep the off state of the high-side FET
until the detection value is gained.
Output voltage setting value
Over current limit operation
DS405-00007-1v0-E
17