MP1593 – 3A, 28V, 385KHz STEP-DOWN CONVERTER

MP1593 Rev. 1.9

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4

9/14/2006

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Refer to Typical Application Schematic on Page 1

100

95

90

85

80

75

70

65

60

55

50

LOAD CURRENT (mA)

Efficiency vs

Load Current

0

500 1000 1500 2000 2500 3000 3500

100

95

90

85

80

75

70

65

60

55

50

0

500 1000 1500 2000 2500 3000 3500

LOAD CURRENT (mA)

Efficiency vs

Load Current

1A/Div.

10mV/Div.

10V/Div.

100mV/Div.

Switching

Waveforms

PIN FUNCTIONS

Pin #

Name Description

1

BS

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET

switch. Connect a 10nF or greater capacitor from SW to BS to power the high-side switch.

2

IN

Power Input. IN supplies power to the IC. Drive IN with a 4.75V to 28V power source. Bypass IN

to GND with a suitably large capacitor to eliminate noise on the input to the IC. See Input

Capacitor.

3

SW

Power Switching Output. SW is the switching node that supplies power to the output. Connect

the output LC filter from SW to the output load. Note that a capacitor is required from SW to BS

to power the high-side switch.

4

GND Ground. Note: Connect the exposed pad to Pin 4.

5

FB

Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage

divider from the output voltage to ground. The feedback threshold is 1.222V. See Setting the

Output Voltage.

6

COMP

Compensation Node. COMP is used to compensate the regulation control loop. Connect a series

RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is

required. See Compensation.

7

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the

regulator; low to turn it off. An Under-Voltage Lockout (UVLO) function can be implemented by

voltage needs to be less than 0.7V. For automatic startup leave EN disconnected.

8

SS

Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND

to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 10ms. To disable the

soft-start feature, leave SS disconnected.