MP5026

– 16V, 20A, 2.8mΩ RDS(ON), HOT-SWAP INTELLI-FUSE SOLUTION

MP5026 Rev. 1.0

MonolithicPower.com

17

7/5/2023

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ILIMIT_SS (A)

0A

ILIMIT (A)

20A

20A

Figure 5: Start-Up and Normal Current Limit

The MP5026 exits start-up when VOUT exceeds

the larger value between VIN - 0.5V and 80% of

VIN, and the power MOSFET gate voltage is

close to the internal charge pump voltage.

Once the MP5026 detects that start-up has

finished, the internal 20A current limit clamp is

disabled.

The

current

limit

during

normal

operation (IOC_NOR) is determined by ILIMIT only.

When the device reaches its current limit

threshold, the internal circuit regulates the gate

voltage to hold constant current in the power

MOSFET. The typical response time is about

20µs.

Intelli-Fuse Over-Current Protection (OCP)

during Start-Up

During start-up, if the current through the

MP5026 is regulated by the SS current limit

(ILIMIT_SS) for the soft-start over-current (OC)

regulation

time

(tOC_REG),

the

gate

stops

regulating and pulls low. Then the soft-start OC

fault is triggered, the power MOSFET shuts

down, and the FLTB and SS pins are pulled low

(see Figure 6).

VOUT

IOUT

FLTB

TIMER

1.21V

4µA

VIN

SS Over-Current Limit

Insertion Delay Time

Figure 6: Soft-Start OCP Behavior

The typical tOC_REG is 1.5ms, where the actual

regulation time depends on the

device’s safe

operating area (SOA). If OTP is triggered during

tOC_REG

,

the

power

MOSFET

shuts

down

immediately.

Over-Current

Protection

(OCP)

during

Normal Operation

Once soft start completes, the MP5026 enters

normal operation. If ILIMIT is triggered, the fault

timer starts. If IOUT drops below ILIMIT before the

fault

timeout

period

completes,

then

the

MP5026 resumes normal operation. Otherwise,

if the OC fault remains longer than the fault

timeout period, the power MOSFET latches off.

The OCP fault time (tOC) can be determined

with Equation (5):

=

OC

TMR

1.21

t

(ms)

C

(nF)

40

(5)

For example, a 10nF capacitor requires a

0.3ms tOC.

If the MP5026 reaches ILIMIT, FLTB is pulled low

with an 8

μs propagation delay to indicate a fault

(see Figure 7).

Normal Over-Current Limit

VOUT

IOUT

FLTB

TIMER

1.21V

40µA

tFAULT

OC Fault Time

Figure 7: Normal OCP Behavior

Short-Circuit Protection (SCP)

If the load current (ILOAD) increases rapidly due

to a short circuit, then the current may exceed

ILIMIT significantly before the hot-swap control

loop can respond. If the Intelli-Fuse current

reaches the short-circuit current limit (ILIMIT_SC)

(typically 50A), then a fast turn-off circuit in the

Intelli-Fuse is activated to turn the power

MOSFET off. This limits the peak current

through the MOSFET to limit the VIN drop. The

total short-circuit response time is about 200ns.