MPQ4560 – 2A, 2MHz, 55V STEP-DOWN CONVERTER
for high duty-cycle operation (when VOUT/VIN >
65%).
The bootstrap diode can be a low cost one such
as IN4148 or BAT54.
Figure 2: External Bootstrap Diode
At no-load or light-load, the converter may
operate in pulse-skipping mode in order to
maintain output-voltage regulation. Thus there is
less time to refresh the BS voltage. For sufficient
gate voltage during pulse-skipping, VIN–VOUT>3V.
For example, if the VOUT=3.3V, VIN must be
exceed 3.3V+3V=6.3V to maintain sufficient BST
voltage at no-load or light-load. To meet this
requirement, the EN pin can program the input
UVLO voltage to VOUT+3V.
MPQ4560 Rev. 1.1
3/29/2013
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