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MP1430

3A, 28V, 385KHz Step-Down Converter

Monolithic Power Systems 

MP1430 – 3A, 28V, 385KHz STEP-DOWN CONVERTER

OPERATION

IN 2

EN 7

INTERNAL

REGULATORS

OSCILLATOR

SLOPE

COMP

40/385KHz

CLK

+

0.7V --

--

SHUTDOWN

COMPARATOR

LOCKOUT

COMPARATOR

2.3V/

2.6V

+

+

--

CURRENT

SENSE

AMPLIFIER

+

--

+

SQ

RQ

--

CURRENT

COMPARATOR

1.8V

FREQUENCY

FOLDBACK

COMPARATOR

-- 0.7V 1.22V + ERROR

AMPLIFIER

5 FB

6 COMP 8 SS

Figure 1—Functional Block Diagram

5V

1 BS

M1

3 SW

M2

4 GND

MP1430_BD01

The MP1430 is a current-mode step-down

regulator. It regulates input voltages from 6V to

28V down to an output voltage as low as 1.22V,

and is able to supply up to 3A of load current.

The MP1430 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 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 internally charged 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 BS.capacitor.

MP1430 Rev. 1.0

11/1/2005

www.MonolithicPower.com

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Free Datasheet http://www.datasheet4u.com/

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