MP44019

– CRM/DCM MULTI-MODE PFC CONTROLLER WITH SECOND OVP

MP44019 Rev. 1.0

MonolithicPower.com

19

4/30/2021

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© 2021 MPS. All Rights Reserved.

An LEB time (tOCL_LEB) of 300ns is applied during

OCL to avoid mistriggering OCL due to a spike

current raised by discharging the drain-source

capacitor of the MOSFET.

CS

LEB Time =

300ns

0.5V

+

-

OCL

Gate

0.75V

+

-

LEB Time =

250ns

R

S Q

Consecutive

Count = 3

OCP

OCP

Timer =

80ms

UVLO

OCP

Figure 12: OCL and OCP

Over-Current Protection (OCP)

A second over-current protection (OCP) is also

integrated in the CS pin with a shorter LEB time

(tOCP_LEB) of 250ns. If the CS voltage exceeds

VOCP (typically 0.75V) for two consecutive 180µs

restart switching cycles, the OCP flag is

triggered, and the IC stops switching. OCP is

reset by an auto-recovery timer (tOCP_R) of 80ms,

as well as the following events: brownin,

brownout, and VCC UVLO. OCP only protects the

device from certain faults, such as an inductor

short or a bypass diode short.

Under-Voltage Protection (UVP) and Over-

Voltage Protection (OVP)

The scaled-down voltage is connected to FB,

which is the input of the under-voltage protection

(UVP)

and

over-voltage

protection

(OVP)

comparators, as well as the error amplifier.

Figure 13 shows that if the FB voltage (VFB)

exceeds the OVP trigger threshold (typically

2.7V), the OVP comparator shuts down the

output of the gate drive circuit after a blanking

time (tBL_OVP) of 22µs. Switching resumes when

VFB drops to 2.62V.

The UVP comparator shuts down if VFB drops

below 0.36V for a blanking time (tBL_UVP) of 55µs.

The UVP comparator

’s hysteresis is 40mV.

If UVP is triggered, COMP is discharged to zero,

and the

device’s supply current is reduced to a

minimum.

The UVP function can disable switching if FB is

open, or if the FB feedback loop is open.

The UVP and OVP comparators values are

described below:

 OVP: V

FB rises above 108% of VREF. Normal

operation resumes when VFB drops below

104% of VREF.

 UVP: V

FB falls below 12% of VREF. Normal

operation resumes when VFB rises above 16%

of VREF.

Second Over-Voltage Protection (OVP2)

The scaled-down voltage is connected to the

OVP2 pin. A second over-voltage protection

(OVP2) is used for applications with a high ripple,

or for a redundant protection for open loops on

the

FB pin. The comparator’s threshold for OVP2

is 108% of VREF, with a hysteresis of 4%.

The second OVP comparator shuts down the

output of the gate drive circuit after a blanking

time of tBL_OVP2 (typically 23μs), see Figure 13.

COMP

FB

CZ

RZ

CP

R1

R2

VOUT

2.5V

UVP

GM

OVP

+

-

+

-

0.3V/0.4V

+

-

60mV

120mV

+

-

FAULT

+

-

2.35V/2.05V

UVLO

PFOKc

2R

R

0.8V

1

Burst

Burst

Blanking

22µs

Blanking

55µs

2.7V/2.6V

OVP2

+

-

Blanking

22µs

2.7V/2.6V

OVP2

Figure 13: FB Functional Block

Gate Driver

The IC includes a push-pull gate driver that can

directly drive the MOSFET. The peak source

current is 600mA, and the peak sink current

capability is 1A.