MP5017 – 3V-5.5V, 1A-5A PROGRAMMABLE CURRENT LIMIT SWITCH

MP5017 Rev.1.0

www.MonolithicPower.com

13

10/15/2015

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blocked, and this state continues until VCC >

VOUT-2mV. When VCC > VOUT-2mV, the part

restarts. If the input voltage drops below the

UVLO threshold, the back-to-back MOSFETs

are turned off, eliminating any reverse current.

Fault

current is detected, Fault reports a fail mode

(low level) after a 5ms deglitch timeout. There is

a 10µs deglitch timeout when the output over

voltage is triggered. This ensures that no false

fault signals are reported. The internal deglitch

circuit

eliminates

the

need

for

external

components.

Fault does not deglitch during an

over-temperature condition (see Table 1).

Table 1: Fault Function Truth Table

Description

Fault

E-Fuse State

Latch

Output Discharge

Under-voltage lockout

High

Off

No

No

EN low

High

Off

No

Yes

SAS/OV high

High

Off

No

Yes

Low

(10μs deglitch time)

High Z

No

No

Thermal shutdown

Low

Off

No

No

Current limit

Low

(5ms deglitch time)

High Z

No

No

Fast current limit

Low

Off

No

No

Reverse current protection

High

Off

No

No

SAS/OV floating

High

On

No

No

SAS/OV low

High

On

No

No

Short-Circuit Protection

If the load current increases too rapidly due to a

short-circuit event, the current may exceed the

current limit threshold before the control loop is

able to respond. If the current reaches 7.5A, a

secondary current limit level from a fast turn-off

circuit is activated. The power FET turns off

with a 100mA pull-down gate discharge current.

This helps limit the peak current through the

switch, keeping the input voltage from dropping

excessively. After the FET is switched off, the

part restarts. If the short remains during the

restart process, the MP5017 regulates the gate

voltage to hold the current at a normal current

limit level.

Output Discharge

The MP5017 uses a discharge function to

provide a resistive discharge path for the

external output capacitor. The function is active

when the part is disabled (EN low or SAS high).

and is done in a very limited amount of time.

EN Control

EN enables the part when it is high and

disables the part when it is low. Floating EN

automatically starts the part up because an

internal current source pulls EN up to the

internal supply. The maximum internal pull-up

voltage source is about 5V.

Thermal Shutdown (OTP Auto-Retry)

Thermal shutdown prevents the chip from

operating at exceedingly high temperatures.

When the silicon die reaches temperatures that

exceed 175°C, the entire chip shuts down and

Fault

reports

a

fail

mode.

When

the

temperature drops below its lower threshold,

typically 125°C, the chip is enable again after a

76ms delay.