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

MP1593 Rev. 1.8

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4

1/6/2006

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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)

MP1593_TPC09

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)

MP1593_TPC08

Efficiency vs

Load Current

1A/Div.

10mV/Div.

10V/Div.

100mV/Div.

MP1593-TPC07

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 the power to the IC, as well as the step-down converter switches. 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 section.

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 on backside to Pin 4).

5

FB

Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive

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

Output Voltage section.

6

COMP

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

RC network from COMP to GND to compensate the regulation control loop. In some cases, an

additional capacitor from COMP to GND is required. See Compensation section.

7

EN

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

regulator, drive EN low to turn it off. An Under Voltage Lockout (UVLO) function can be

shutdown its needs to be less than 0.7V. For automatic startup, leave EN unconnected.

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 unconnected.