MP4462 – 3.5A, 4MHz, 36V STEP-DOWN CONVERTER
This diode is also recommended for high duty
cycle operation (when VOUT /VIN >65%) or low
VIN (<5Vin) applications.
External Bootstrap Diode
It is recommended that an external bootstrap
diode be added when the input voltage is no
greater than 5V or the 5V rail is available in the
system. This helps improve the efficiency of the
regulator. The bootstrap diode can be a low
cost one such as IN4148 or BAT54.
At no load or light load, the converter may
operate in pulse skipping mode in order to
maintain the output voltage in regulation. Thus
there is less time to refresh the BS voltage. In
order to have enough gate voltage under such
operating conditions, the difference of VIN –VOUT
should be greater than 3V. For example, if the
VOUT is set to 3.3V, the VIN needs to be higher
than 3.3V+3V=6.3V to maintain enough BS
voltage at no load or light load. To meet this
requirement, EN pin can be used to program
the input UVLO voltage to Vout+3V.
5V
BS
MP4462
SW
Figure 3—External Bootstrap Diode
MP4462 Rev. 1.02
3/4/2013
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