MP4560 – 2A, 2MHz, 55V STEP-DOWN CONVERTER
BLOCK DIAGRAM
VIN
REFERENCE
UVLO
INTERNAL
REGULATORS
EN
BST
--
+
ISW
LOGIC
0.5ms SS
SS
SW
--
+
FB
COMP
SS
0V8
OSCILLATOR
FREQ
COMP
GND
Figure 1—Functional Block Diagram
the power MOSFET does not reach the COMP
set current value, the power MOSFET remains
on, saving a turn-off operation.
OPERATION
The MP4560 is a programmable frequency,
non-synchronous, step-down switching regulator
with an integrated high-side high voltage power
MOSFET. It provides a single highly efficient
solution with current mode control for fast loop
response and easy compensation. It features a
wide input voltage range, internal soft-start
control and precision current limiting. Its very low
operational quiescent current makes it suitable
for battery powered applications.
Pulse Skipping Mode
Under light load condition the switching
frequency stretches down zero to reduce the
switching loss and driving loss.
Error Amplifier
The error amplifier compares the FB pin voltage
with the internal reference (REF) and outputs a
current proportional to the difference between the
two. This output current is then used to charge
the external compensation network to form the
COMP voltage, which is used to control the
power MOSFET current.
PWM Control Mode
At moderate to high output current, the MP4560
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 the
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
During operation, the minimum COMP voltage is
clamped to 0.9V and its maximum is clamped to
2.0V. COMP is internally pulled down to GND in
shutdown mode. COMP should not be pulled up
beyond 2.6V.
MP4560 Rev. 1.0
11/5/2012
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