MP163 – 700V, NON-ISOLATED, OFFLINE REGULATOR WITH INTEGRATED LDO

MP163 Rev. 1.01

www.MonolithicPower.com

15

8/11/2017

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Open-Loop Detection

If

switching

soft start, the open-loop detection is blanked.

Leading-Edge Blanking (LEB

)

An internal leading-edge blanking (LEB) unit

avoids premature switching pulse termination

due to a turn-on spike. A turn-on spike is

caused by parasitic capacitance and reverse

recovery of the freewheeling diode. During the

blanking time, the current comparator is

disabled and cannot turn off the external

MOSFET. Figure 5 shows the leading-edge

blanking.

350ns

t

Figure 5: Leading-Edge Blanking

Integrated LDO

The continuous output current of the integrated

LDO is up to 150mA but is also limited by the

thermal performance. The peak output current

is limited to 270mA in OLP.

When the input of the integrated LDO (usually

the high-side buck output of the MP163) is

much higher than its output, there is a large

power dissipation on the MP163, which

worsens the thermal performance. An external

resistor connected to IN can help with the LDO

thermal by sharing part of the total voltage drop.