MP5016H

– 2.7 - 22V, 0.7 - 5A, PROGRAMMABLE, CURRENT-LIMITED SWITCH

MP5016H Rev.1.0

www.MonolithicPower.com

11

5/25/2017

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© 2017 MPS. All Rights Reserved.

OPERATION

The MP5016H 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

MP5016H 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 MP5016H can be used in a 2.7V to 22V

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

MP5016H

integrates

a

high-voltage

MOSFET with up to 22V of continuous voltage

and 26V of maximum transient input voltage.

The MP5016H 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 also be set

by connecting a resistor from MODE to ground.

For more details, refer to the Application

Information section on page 13.

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 MP5016H

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 (ILIMIT)

The MP5016H 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 MP5016H 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.