MP245136V, 2MHz, 0.6A, STEP-DOWN CONVERTER
MP2451 Rev. 1.33 www.MonolithicPower.com
4/29/2014 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
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FUNCTION BLOCK DIAGRAM
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EN
REFERENCE
UVLO
0.5ms SS
LOGIC
OSCILATOR
2MHz
SS
COMP
ISW
ISW
INTERNAL
REGULATOR
VIN
FB
GND
BST
SW
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0.8V
SS
Figure 1—Function Block Diagram
OPERATION
The MP2451 is a 2MHz, non-synchronous, step-
down switching regulator with integrated internal
high-side high voltage power MOSFET. It
provides internally compensated single 0.6A
highly efficient output with current mode control.
It features wide input voltage range, internal soft-
start control, and precision current limit. Its very
low operational quiescent current suits it for
battery powered applications.
PWM Control
At moderate to high output current, the MP2451
operates in a fixed frequency, peak current
control mode to regulate the output voltage. A
PWM cycle is initiated by the internal clock. The
power MOSFET is turned on and remains on
until its current reaches the value set by COMP
voltage. When the power switch is off, it remains
off for at least 100ns before the next cycle starts.
If, in one PWM period, the current in the power
MOSFET does not reach COMP set current
value, the power MOSFET remains on, saving a
turn-off operation.
Pulse Skipping Mode
At light load condition, the MP2451 goes into
pulse skipping mode to improve light load
efficiency. Pulse skipping decision is based on its
internal COMP voltage. If COMP is lower than
the internal sleep threshold, a PAUSE command
is generated to block the turn-on clock pulse so
the power MOSFET is not commanded ON
subsequently, saving gate driving and switching
losses. This PAUSE command also puts the
whole chip into sleep mode, consuming very low
quiescent current to further improve the light load
efficiency.
