MP5991

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

MP5991 Rev. 1.0

MonolithicPower.com

22

4/27/2022

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© 2022 MPS. All Rights Reserved.

Then the rise time is controlled by the load

capacitor and ILIMIT. Float the SS pin to generate

a fast ramp-up voltage. A current source (

12μA)

pulls up the MOSFET gate. The gate charge

current controls the VOUT rise time, and tSS is

about 1.5ms, which is the minimum VOUT tSS.

If multiple MP5991s are operating in parallel,

then their SS pins should be connected. This

controls the soft-start slew rate for all of the

devices in parallel during soft start.

Start-Up Sequence

For hot-swap applications where VIN rises

immediately, VGATE should be pulled low during

VIN plug-in with high dv/dt. The MP5991 has two

operation modes: standalone mode and slave

mode.

Standalone Mode

In standalone mode, connect an

external

capacitor (CON) between the ON and GND pins

for automatic start-up. Figure 8 shows a typical

application circuit of the MP5991 in standalone

mode.

VIN

VOUT

VIN

VOUT

CS

IMON

GOK

SS

OCREF

VTEMP

VDD33

GND

FLT_TYPE

D_OC

TVS

SCREF_

OCWREF

MP5991

MODE

ON

Fault Type Indication

ROCREF

RSCREF

RCS

CON

RIMON

CSS

RMODE

CVDD33

RVTEMP

CVTEMP

COCREF

Figure 8: MP5991 Typical Application Circuit in

Standalone Mode

The internal current source (4.2µA) charges

CON once the VDD33 voltage (VDD33) exceeds

its UVLO rising threshold. ON can also be

pulled up to VDD33 externally. The OCREF

current (IOCREF) (10µA) determines the over-

current (OC) limit (ILIMIT_OC) level via the OCREF

resistor (ROCREF). The SCREF current (ISCREF)

(10µA) determines ILIMIT_SC level via the SCREF

resistor (RSCREF).

Once VON exceeds 1.4V and tON_DELAY finishes,

the MOSFET is charged by the internal

12μA

charge pump. The MOSFET turns on once the

gate-to-source (GS) voltage (VGS) exceeds its

threshold (VGS_TH), and VOUT rises. If the

external current-limit reference voltage (VOCREF)

exceeds the internal VSS_CLAMP, then the actual

current-limit reference is clamped internally at

VSS_CLAMP (see Figure 9). If the external VOCREF

is below VOCREF_CLAMP, then the current-limit

reference is determined by VOCREF.

t

VIN

VGS

VOUT

VCP = 3.3V

VDD33

VDD33 UVLO

VGOK

VON

VOCREF

tON_DELAY

1.4V

VSS_CLAMP

80% of VIN

VCS

VSCREF_

OCWREF

(e.g. 1.4V)

Figure 9: Start-Up in Standalone Mode

Slave Mode

If the MP5991 is controlled by a hot-swap

master or controller (e.g. design with the

MP5990), then the part should be configured to

operate in slave mode. In slave mode, VOCREF,

VSCREF, and the OCWREF voltage (VOCWREF) are

configured via the controller.

The MOSFET remains off until VON is pulled

high. If VON goes high and tON_DELAY finishes,

then the MOSFET is charged by the internal

12μA charge pump. VOUT rises once VGS

exceeds VGS_TH (see Figure 10).

t

VIN

VGS

VOUT

VCP = 3.3 V

VDD33 UVLO

VGOK

VON

VOCREF

VSS_CLAMP

tON_DELAY

The on delay is determined

by the controller

>1.4V

VCS

VSCREF_

OCWREF

VSCREF

VOCWREF

VDD33

(e.g. 1.4V)

Figure 10: Start-Up while the MP5991 is

Controlled via a Hot-Swap Controller