MP5991

– 16V, 50A, 1mΩ RDS(ON), HOT-SWAP INTELLI-FUSE SOLUTION

MP5991 Rev. 1.0

MonolithicPower.com

27

4/27/2022

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the device attempts to retry automatically, and

GOK is pulled high after tRETRY. FLT_TYPE

continues to indicate an OV fault during tRETRY.

FLT_TYPE is reset to 0.1V after tRETRY.

Damaged Intelli-Fuse MOSFET Detection

The MP5991 can detect a shorted pass

MOSFET during start-up. Once VDD33 exceeds

its UVLO rising threshold and VON exceeds its

rising threshold (1.4V), the device treat output

voltages that exceed 90% of VIN during the

tON_DELAY as a short. This is called a drain-to-

source (DS) short. GOK is pulled low once the

device detects that VOUT has exceeded 90% of

VIN during start-up, and FLT_TYPE outputs

0.6V to indicate a DS short. The DS short is

non-latch fault, regardless of the operation

mode. GOK is pulled high once the DS short is

removed and the device detects that VOUT is

below 70% of VIN. Then FLT_TYPE is reset to

0.1V. The MP5991 initiates a soft start and

resumes normal operation.

Power MOSFET is Not Fully On

If the following conditions are met once the part

starts up and VOUT starts to ramp up, it means

the power MOSFET is not fully on:

• V

SS exceeds VDD33 - 0.7V

• V

GS is below VCP - 0.7V

• No OC faults have occurred

• No SC faults have occurred

The MP5991 stops regulating and the MOSFET

turns off after 250ms. The GOK and SS pins

are pulled low, and FLT_TYPE outputs 0.6V to

indicate a GS short has occurred (see Figure

15).

t

VIN

VGS

VDD33

VDD33 UVLO

VGOK

VON

tON_DELAY

1.4V

VSS

250ms

VCP

VOUT

(e.g. 2.7V)

Below VCP - 0.7V

Figure 15: Power MOSFET is Not Fully On in

Latch-Off Mode

In latch-off mode, cycle the power on VIN,

VDD33, or ON to reset FLT_TYPE to 0.1V. This

initiates a soft start, and then MOSFET turns on.

In hiccup mode, the device attempts to retry

automatically, and GOK is pulled high after

tRETRY ends. FLT_TYPE continues to indicate a

GS short fault during tRETRY. FLT_TYPE is reset

to 0.1V after tRETRY.

GOK Fault

The MP5991 provides a comparator on the

GOK pin to control the MOSFET. If VGOK drops

below 1.16V, then the system sees this as a

fault, and the MOSFET turns off after a delay

time (10µs). FLT_TYPE outputs 0.3V to indicate

a GOK fault.

The GOK fault is non-latch fault. Once VGOK

exceeds 2.06V, the device initiates a soft start

and resumes normal operation. FLT_TYPE

resets to 0.1V.

For standalone operation, GOK has an internal

pull-up

resistor

(370k

Ω) to avoid falsely

triggering a GOK fault when there is not an

external pull-up resistor.

Under-Voltage Lockout (UVLO) Protection

The MP5991 has two under-voltage lockout

(UVLO) protections: VDD33 UVLO with a 2.7V

rising threshold, and VIN UVLO with a 3.2V

rising threshold. The device starts up once both

VDD33 and VIN exceed their respective rising

thresholds. The MP5991 shuts down if either

VDD33 or VIN drops below its UVLO (2.3V and

2.7V, respectively). VDD33 UVLO and VIN UVLO

are non-latch protections.

Input and Output Transient Protection

Parasitic inductance in the input circuitry can

cause the hot-swap system to experience

positive transients on the input during a hot plug

or during rapid shutdown with a high current. To

reduce input transients, a transient voltage

suppressor (TVS) diode may be required on the

input to limit transient voltages below the

absolute maximum ratings.

Inductance in the output circuitry can cause the

output to experience negative transients during

rapid turn-off with a high current. If a transient

causes the output to drop further, then the

MOSFET may not turn off properly.