MP62550/MP62551 –60mA-1.7A PROGRAMMABLE CURRENT-LIMITED POWER DISTRIBUTION SWITCHES

MP62550/MP62551 Rev. 1.21

www.MonolithicPower.com

12

6/27/2013

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2013 MPS. All Rights Reserved.

APPLICATION INFORMATION

Power-Supply Considerations

Over 10μF capacitor between IN and GND is

recommended. This precaution reduces power-

supply transients that may cause ringing on the

input and improves the immunity of the device

to short-circuit transients.

In order to achieve smaller output load transient

ripple, placing a high-value electrolytic capacitor

on the output pin is recommended when the

load is heavy.

A 0.01μF to 0.1μF ceramic bypassing capacitor

is recommended to improve the immunity of the

device to transient conditions and noise.

GND

IN

ILIM

EN

OUT

FLAG

GND

VIN

EN

VOUT

GND

MP62551

*

*

10k

FLAG

+

PAD

* EN is active low for MP62550

Figure 4—Application Circuit

Programming the Current-Limit

The current-limit is programmed via an external

resistor from ILIM to GND. The recommended

1%

resistor

range

of

is

connected to IN to set the current-limit at its

minimum level of 60mA (typ).

It’s important to consider the tolerance of

Some applications require that the minimum

current limit is above a certain current level,

while some applications require the maximum

current limit is below a certain current level.

Figure 5 can be used to calculate the current

limit value for a given ILIM resistor and also can

be used to select ILIM resistor for a certain

current limit.

that occurs 1) above a minimum load current or

2) below a maximum load current.

To determine above a minimum current limit,

find the maximum desired load current on the

this value. The resulting maximum current limit

To determine below a maximum current limit,

find the maximum desired load current on the

this value. The resulting minimum current limit

In theory, the result of current limit multiplied by

not linear at small programming resistor range.

The theoretical current limit calculation formula

is given as following:

OSnom

0.9248

ILIM

18.818V

I(A)

Rk

=

Ω

OS min

0.9342

ILIM

18.489V

I(A)

Rk

=

Ω

OS max

0.8944

ILIM

18.229V

I(A)

Rk

=

Ω

Where:

ILIM

12.4k

R

210k

Ω ≤≤

For better accuracy current limit setting, Table1

and Figure5 are highly recommended. Those

curve or data are provided basing on large

amount experimental test results.