MP5018 –5V, 1A-5A CURRENT LIMIT SWITCH WITH REVERSE CURRENT BLOCKING

AND OUTPUT OVER-VOLTAGE CLAMP

MP5018 Rev. 1.02

www.MonolithicPower.com

12

3/23/2016

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© 2016 MPS. All Rights Reserved.

EN Control/Fault Indication

The EN Pin enables the part when high and

disables the part when low. Floating the EN pin

will set the part auto startup because there is

internal current source pull up EN to internal

supply. The maximum internal pull up voltage

source is about 5V. EN/Fault pin is also a bi-

directional function node. When the part

entersthermal shutdown, EN/Fault pin outputs

middle level voltage ~1.3V to indicate fault

or the SAS pin is high, the EN pin will be pulled

to GND through an internal resistor.

Table 1: Enable/Fault Function

Description

Enable/Fault

EFuse State

Latch

Under Voltage Lock Out

Low

Off

No

SAS = High

Low

Off

No

Thermal Shutdown

Mid

Off

Yes

Reverse Current Protection

Mid

Off

No (part restarts when

SAS Floating

High

On

N/A

SAS = Low

High

On

N/A

SAS Control

The SAS pin also can control the part startup

and shutdown. When floating this pin or pull it

low, it enables the part and disables the part

when pull high.

Soft-Start

Floating SS pin can get 13ms soft start time.

While a capacitor connected to the SS pin can

set the soft start time. A constant current source

charges the SS capacitor and results in a linear

ramping voltage on the SS pin. The output

voltage rises at a similar slew rate to the SS

voltage.

The soft-start time can be calculated as follows:

ss

ss

1V C (nF)

t(ms)

6.5 A

×

=

μ

Where:

For example, a 22nF capacitor gives a soft start

time of ~3.4ms.

If the load capacitance is extremely large, the

current required to maintain the preset soft start

time will exceed the current limit. In this case

the rise time is controlled by the load capacitor

and the current limit.

Thermal Shutdown – Latch Off

Thermal shutdown prevents the chip from

operating at exceedingly high temperature.

When the silicon die reaches temperature that

exceeds 175°C, it shuts down the whole chip,

and drives the Enable/Fault line to the middle

(MID) level. The chip is latched off after trigger

the thermal protection and it restarts when

toggle the EN or SAS or recycle the input

supply.