MP5048

– 60V, 15A, 7mΩ RDS(ON) HOT-SWAP INTELLI-FUSE SOLUTION

MP5048 Rev. 1.1

www.MonolithicPower.com

15

4/30/2021

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© 2021 MPS. All Rights Reserved.

If the ON voltage exceeds the rising threshold

when the insertion delay time ends, the power

FET charges up via the internal 26

μA current

source. The power FET turns on when VGS

reaches VGSTH, and then the output voltage rises

(see Figure 8).

t

VIN

FAULT

VOUT

VCC

MP5048 UVLO

ON

SS Limit

Insertion Delay

VCLREF

VGS

VCLREF_NORM

VCS

Figure 8: Start-Up when the MP5048 Operates in

Standalone Mode

Soft Start (SS)

A capacitor connected to the SS pin determines

the soft-start (SS) time. When the ON pin is

pulled high and the insertion delay time ends, a

constant current source proportional to the input

voltage charges up the SS voltage. The output

voltage rises at a similar slew rate to the SS

voltage.

The SS capacitor value can be calculated with

Equation (1):

SS

SS

SS

R

t

15

C





(1)

Where tSS is the soft-start time (ms), CSS is the

soft-start capacitor (nF), and RSS is 3.6MΩ.

For example, a 100nF capacitor provides a soft-

start time of 24ms. If the load capacitance is

extremely large, the current required to maintain

the preset SS time exceeds the start-up current

limit. In this case, the rise time is controlled by

the load capacitor and the start-up current limit.

Float SS to generate a fast ramp-up voltage.

A 26

μA current source pulls up the power FET

gate. The gate charge current controls the output

voltage rise time. The approximate soft-start time

is 1.5ms, which is the minimum output voltage

soft start time.

When the MP5048 is used in multi-phases

application, all SS pins should be connected

together, which ensures all devices have the

same SS time.

If a fault condition occurs, the fault and SS pins

are pulled low. If the MP5048 is configured for

auto-retry mode, the SS pin is held low until the

retry time has expired. When the retry time ends,

the MP5048 can re-enable the FET, then enter

the soft start turn-on sequence.

TIMER Pin

The TIMER pin serves 4 functions:

1. Insertion delay

2. Turns on the short-circuit protection (SCP)

timer

3. Over-current protection (OCP) timer

4. Sets the retry time

When the MP5048 passes internal power-on

reset (POR), the insertion delay begins by

charging the capacitor with a 2

μA current source.

When the voltage reaches the threshold, the

TIMER pin is pulled up by the internal 4V source

for 3.5

μs (the actual pull-up voltage depends on

the external timer capacitor), then resets quickly

to GND for 7.5

μs. The timer repeats this, and

then the insertion delay time is completed (see

Figure 9).

t

VOUT

Insertion Delay

TIMER

4V

2.4V

3.5µs Hold

7.5µs

Hold

VCC

MP5048 UVLO

2µA

ON

FAULT

Figure 9: MP5048 Insertion Delay Time