MP5075L

MP5075L Rev 1.0

www.MonolithicPower.com

10

2/3/2017

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2017 MPS. All Rights Reserved.

OPERATION

The MP5075L is designed to limit the inrush

current to the load when a circuit card is

inserted into a live backplane power source,

thereby limiting the backplane’s voltage drop

and the slew rate of the voltage to the load. The

MP5075L provides an integrated solution to

monitor the input voltage, output voltage, and

output current to eliminate the need for an

external current power MOSFET and current

switch device.

Enable (EN)

When the input voltage is greater than the

under-voltage

lockout

(UVLO)

threshold

(typically 2.6V), the MP5075L can be enabled

by pulling EN above 1.5V. Pull EN down to

ground to disable the MP5075L.

Current Limit

The MP5075L provides an internal, fixed, 1.4A,

constant current limit. Once the device reaches

its current limit threshold, the internal circuit

regulates the gate voltage to hold the current in

the power MOSFET constant. The typical

response time is about 20µs. The output current

may have a small overshoot during this time

period.

If the current limit block starts to regulate the

output current, the power loss on the power

MOSFET causes the IC temperature to rise. If

the junction temperature rises high enough,

thermal shutdown is triggered. After thermal

shutdown occurs, the output is disabled until

the over-temperature fault is removed. The

over-temperature

threshold

is

150°C,

and

hysteresis is 30°C.

Short-Circuit Protection (SCP)

If the load current increases rapidly due to a

short circuit, the current may exceed the current

limit threshold greatly before the control loop

can respond. If the current reaches an internal

secondary current limit level (typically 7A), a

fast turn-off circuit activates to turn off the

power MOSFET. This limits the peak current

through the switch to limit the input voltage drop.

The total short-circuit response time is about

200ns. If fast turn-off is effective, the power

MOSFET remains off

for 80μs. Afterward, the

power MOSFET is turned on again. If the part is

still in the short-circuit condition, the MP5075L

enters current limit until the part is hot enough

to trigger thermal shutdown. After the short-

circuit condition is removed, the MP5075L auto-

retries after the silicon temperature drops.

Output Discharge

The

MP5075L

has

an

output

discharge

function. This function can discharge VOUT by

the internal pull-down resistance when the IC is

disabled and the load is very light.

Soft Start (SS)

Soft start prevents large inrush current. The

soft-start time is set to 450

μs internally.

PCB Layout Guidelines

Efficient

PCB

layout

is

critical

for

stable

operation. For best results, refer to Figure 2 and

follow the guidelines below.

1. Place an input capacitor close to VIN.

2. Connect NC to GND for an easier layout.

3. Place enough vias around the IC and

enough copper area near VIN and VOUT to

achieve better thermal performance.

Figure 2: Recommended Layout