MP2363 – 3A, 27V, 365KHz STEP-DOWN CONVERTER
OPERATION
The MP2363 is a current-mode step-down
regulator. It regulates an input voltage between
4.75V to 27V down to an output voltage as low as
0.92V, and is able to supply up to 3A of load
current.
The MP2363 uses current-mode control to
regulate the output voltage. The output voltage
is measured at the FB pin through a resistive
voltage divider and amplified through the internal
error amplifier. The output current of the
transconductance error amplifier is presented at
COMP where a network compensates the
regulation control system. The voltage at COMP
is compared to the switch current measured
internally to control the output voltage.
The converter uses an internal N-Channel
MOSFET switch to step-down the input voltage
to the regulated output voltage. Since the
MOSFET requires a gate voltage greater than
the input voltage, a boost capacitor connected
between SW and BS drives the gate. The
capacitor is charged by an internal 5V supply
while SW is low.
An internal 10Ω switch from SW to GND is used
to insure that SW is pulled to GND when SW is
low to fully charge the boost.capacitor.
IN 2
INTERNAL
REGULATORS
OSCILLATOR
35KHz/
365KHz
+
SLOPE
COMP
CLK
CURRENT
SENSE
AMPLIFIER
+
--
5V
1
Q
Q
3
BS
+
S
R
1.2V
EN 7
--
SHUTDOWN
COMPARATOR
LOCKOUT
COMPARATOR
--
CURRENT
COMPARATOR
SW
--
2.54V/
2.33V
+
+
--
1.8V
4
GND
FREQUENCY
FOLDBACK
COMPARATOR
--
0.35V
5
0.92V
FB
SS
8
+
ERROR
AMPLIFIER
6
COMP
Figure 1—Functional Block Diagram
MP2363 Rev. 1.0
6/15/2006
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