MP2228 – SYNCHRONOUS STEP-DOWN CONVERTER

MP2228 Rev. 1.1

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10

8/20/2013

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exceeds 5V, U1 will regulate M1 to maintain a

5V BST voltage across C4. A 20Ω resistor

placed between SW and BST cap. is strongly

recommended to reduce SW spike voltage.

D1

5V

M1

U1

BST

C4

SW

L1

C2

R3

Figure 2: Internal Bootstrap Charging Circuit

Startup and Shutdown

The reference block starts first, generating

stable reference voltage and currents, and then

the internal regulator is enabled. The regulator

provides a stable supply for the remaining

circuitries.

and thermal shutdown. During the shutdown

procedure, the signaling path is first blocked to

avoid any fault triggering. The COMP voltage

and the internal supply rail are then pulled down.

The floating driver is not subject to this

shutdown command.