MP5016 – 2.7 - 15V, 0.7 - 5A, PROGRAMMABLE, CURRENT-LIMITED SWITCH

MP5016 Rev.1.1

www.MonolithicPower.com

11

6/14/2019

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© 2019 MPS. All Rights Reserved.

OPERATION

The MP5016 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 dV/dt of the voltage to the load. The

MP5016 offers an integrated solution that

monitors the input voltage, output voltage,

output current, and die temperature, which

eliminates the requirement of an external

current sense power resistor, power MOSFET,

and thermal sense device.

Under-Voltage Lockout (UVLO)

The MP5016 can be used in the 2.7V to 15V

input supply system. There are high-energy

transients during normal operation or hot swaps.

These transients depend on the parasitic

inductance and resistance of the wire and the

capacitor at the VCC node. If a power clamp

(TVS, Tranzorb) diode is not used, the E-fuse

must be able to withstand this transient voltage.

The

MP5016

integrates

a

high-voltage

MOSFET with up to 15V of continuous voltage

and 26V of maximum transient input voltage.

The MP5016 also uses a high-voltage circuit for

the VCC node to guarantee safe operation.

MODE

MODE is used to select the output over-voltage

protection (OVP) threshold.

Three digital inputs are provided for MODE.

Drive MODE high to VCC to set the output OVP

clamp voltage at 15.2V. Drive MODE low to

GND to set the output OVP clamp voltage at

5.75V. Float MODE for no OVP clamp

protection. The OVP threshold can be set by

connecting a resistor from MODE to ground.

For more details, refer to the Application

Information section on page 14.

Soft Start (SS)

The soft-start time is related to the dV/dt slew

rate and input voltage and can be calculated

with Equation (1):

(V/ms)

dv/dt

Vin(V)

t_ss(ms)



(1)

The dV/dt slew rate is controlled by an external

DV/DT capacitor setting and the MODE setting.

Fast Output and Input OVP

To protect the downstream load when there is a

surge voltage at the input, the MP5016 provides

an output OVP function. An accurate and fast

comparator monitors the over-voltage condition

of the output. If the output voltage rises above

the threshold set by MODE, the gate of the

internal MOSFETs is pulled down quickly and is

regulated to a certain value to keep the output

voltage clamped at the OVP threshold. The fast

loop response speed keeps the over-voltage

overshoot small.

Current Limit

The MP5016 provides a constant current limit,

and the current limit can be programmed by an

external resistor.

The desired current limit is a function of the

external current limit resistor and can be

approximated with Equation (2):

LIMIT

LIMIT

0.55(V)

I

(A)

3870

R(Ω



）

(2)

Where 3870 is the current sense ratio.

Once the current limit threshold is reached, the

internal circuit regulates the gate voltage to hold

the current in the power MOSFET constant. To

limit the current, the gate to the source voltage

must be regulated from 5V to around 1V. The

typical response time is about 15µs. During this

period, the output current may have a small

overshoot.

If the current limit condition lasts longer than

2ms, the IC enters hiccup mode with 2ms of on

time and 700ms of off time.

The MP5016 allows ILIMIT to be floated during

operation. If ILIMIT is floating, the current limit

is set at a fixed 2.5A internally.

When shorting ILIMIT to GND, the normal

current limit is disabled, but the secondary

current limit still works. The secondary current

limit is set to 8A internally. When the secondary

current limit is triggered, the IC shuts down the

power MOSFET.