MP2357

– 0.5A, 24V, 1.4MHz STEP-DOWN CONVERTER IN A TSOT23-6

MP2357 Rev. 1.0

www.MonolithicPower.com

3

6/13/2013

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© 2013 MPS. All Rights Reserved.

ELECTRICAL CHARACTERISTICS

Parameters

Symbol

Condition

Min

Typ

Max

Units

Feedback Voltage

4.5V

 V

0.790

0.810

0.830

V

Feedback Current

10

nA

Switch-On Resistance

(5)

0.35

Ω

Switch Leakage

10

μA

Current Limit

(5)

0.8

A

Oscillator Frequency

1.4

MHz

Fold-back Frequency

460

KHz

Maximum Duty Cycle

87

%

Minimum On-Time

(5)

100

ns

Under Voltage Lockout Threshold Rising

2.5

2.8

3.1

V

Under Voltage Lockout Threshold Hysteresis

150

mV

EN Input Low Voltage

0.4

V

EN Input High Voltage

1.2

V

EN Input Current

2.1

μA

0.01

Supply Current (Shutdown)

0.1

1.0

μA

Supply Current (Quiescent)

0.8

1.0

mA

Thermal Shutdown

(5)

150

°C

Note:

5) Guaranteed by design.

PIN FUNCTIONS

Pin #

Name Description

1

BST

Bootstrap. This capacitor is needed to drive the power switch’s gate above the supply voltage. It

is connected between SW and BS pins to form a floating supply across the power switch driver.

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 above 1.2V to turn the device on.

5

IN

Supply Voltage. The MP2357 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.