MP1542 – 700KHz/1.3MHz BOOST CONVERTER WITH A 2A SWITCH
PIN FUNCTIONS
Pin # Name Description
1
2
COMP Compensation Pin. Connect a capacitor and resistor in series to ground for loop stability.
FB
Feedback Input. Reference voltage is 1.25V. Connect a resistor divider to this pin.
Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns
it off. When not used, connect EN to the input source (through a 100kΩ pull-up resistor if VIN >
6V) for automatic startup. EN cannot be left floating.
3
EN
4
5
6
7
GND Ground.
Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power
inductor and output rectifier to SW. SW can swing between GND and 25V.
SW
IN
Input Supply Pin. IN must be locally bypassed.
Frequency Select Pin. Tie to IN (through a 100kΩ resistor if VIN > 6V) for 1.3MHz operation or to
GND for 700KHz operation.
FSEL
Soft-Start Control Pin. Connect a soft-start capacitor to this pin. The soft-start capacitor is
charged with a constant current of 6µA.
8
SS
OPERATION
The MP1542 uses a constant frequency, peak
current mode boost regulation architecture to
regulate the feedback voltage.
The operation of the MP1542 can be
understood by referring to the block diagram of
Figure 1.
IN
6
INTERNAL REGULATOR
AND ENABLE CIRCUITRY
EN
3
7
OSCILLATOR
FSEL
5
SW
+
--
PWM
CONTROL
LOGIC
CURRENT
SENSE
AMP
+
--
4
2
GND
FB
--
GM
+
1.25V
SS
8
1
COMP
MP1542_BD01
Figure 1—Functional Block Diagram
MP1542 Rev. 1.2
12/14/2005
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5
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