MP2303DN Monolithic Power Systems, MP2303DN Datasheet - Page 7

• Manufacturer Part Number: MP2303DN
• Description: 3A, 28V, 340khz Synchronous Rectified Step-down Converter
• Manufacturer: Monolithic Power Systems

OPERATION
The MP2303 is a synchronous rectified,
current-mode, step-down regulator. It regulates
input voltages from 4.75V to 28V down to an
output voltage as low as 0.8V, and supplies up
to 3A of load current.
The MP2303 uses current-mode control to
regulate the output voltage. The output voltage
is measured at FB through a resistive voltage
divider and amplified through the internal
transconductance error amplifier. The voltage at
COMP pin is compared to the switch current
measured internally to control the output
voltage.
MP2303 Rev. 0.92
5/2/2006
COMP
EN
FB
SS
TM
0.95V
0.3V
0.8V
2.5V
1.5V
MP2303 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
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+
--
--
+
+
--
+
+
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MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
COMPARATOR
COMPARATOR
SHUTDOWN
AMPLIFIER
LOCKOUT
ERROR
EN OK
Figure 1—Functional Block Diagram
OVP
OSCILLATOR
340KHz
INITIAL RELEASE – SPECIFICATIONS SUBJECT TO CHANGE
© 2006 MPS. All Rights Reserved.
www.MonolithicPower.com
RAMP
CLK
1.2V
The
MOSFET switches to step-down the input
voltage to the regulated output voltage. Since
the high-side MOSFET requires a gate voltage
greater than the input voltage, a boost capacitor
connected between SW and BS is needed to
drive the high-side gate. The boost capacitor is
charged from the internal 5V rail when SW is low.
When the MP2303 FB pin exceeds 20% of the
nominal regulation voltage of 0.8V, the over
voltage comparator is tripped; the COMP pin
and the SS pin are discharged to GND, forcing
the high-side switch off.
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COMPARATOR
CURRENT
converter
R
S
AMPLIFIER
CURRENT
SENSE
Q
Q
uses
REGULATORS
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INTERNAL
internal
IN
OVP
IN < 4.05V
5V
N-Channel
MP2303_BD01
IN
BS
SW
GND
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