MP29368 – 1.2A, 24V, 1.4MHz STEP-DOWN CONVERTER IN A TSOT23-6

MP29368 Rev. 1.2

www.MonolithicPower.com

3

12/13/2007

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© 2007 MPS. All Rights Reserved.

TM

PIN FUNCTIONS

Pin #

Name Description

1

BST

Bootstrap. A capacitor is connected between SW and BS pins to form a floating supply across

the power switch driver. This capacitor is needed to drive the power switch’s gate above the

supply voltage.

2

GND

Ground. This pin is the voltage reference for the regulated output voltage. For this reason care

must be taken in its layout. This node should be placed outside of the D1 to C1 ground path to

prevent switching current spikes from inducing voltage noise into the part.

3

FB

Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets the

output voltage. To prevent current limit run away during a short circuit fault condition, the

frequency foldback comparator lowers the oscillator frequency when the FB voltage is below

250mV.

4

EN

On/Off Control Input. Pull EN above 1.2V to turn the device on.

5

IN

Supply Voltage. The MP29368 operates from a +4.5V to +24V unregulated input. C1 is needed

to prevent large voltage spikes from appearing at the input.

6

SW

Switch Output.

TYPICAL PERFORMANCE CHARACTERISTICS

Efficiency vs

Load Current

100

90

80

70

60

50

40

30

20

10

0

LOAD CURRENT (A)

100

90

80

70

60

50

40

30

20

10

0

0.01

0.1

1

10

LOAD CURRENT ( A)

Efficiency vs

Load Current

Feedback Voltage vs

Die Temperature

0.820

0.818

0.816

0.814

0.812

0.810

0.808

0.806

0.804

0.802

0.800

-50 -25 0 25

75 100 125

50

150

Switching Frequency vs

Die Temperature

1.50

1.48

1.46

1.44

1.42

1.40

1.38

1.36

1.34

1.32

1.30

-50 -25 0 25

75 100 125

50

150

0.01

0.1

1

10