PFS5176F datasheet(11/25 Pages) POWERINT

11 / 25 page

Rev. C 03/22

PFS5173-5178/5274

www.power.com

The low-line OCP (the greater of the two settings) is selected when

the peak of the input line voltage drops below 140 VAC for 3

consecutive half-cycles and the high-line OCP level (the lesser of the

two settings) is selected when the input line voltage rises above 170

VAC for 1 half-cycle, (except in follower mode, as described in the

subsequent sections).

The HiperPFS-5 IC implements a high input line OCP after detecting

the VOLTAGE MONITOR pin voltage being above the high-line

threshold, V

HIGH+. The controller reverts back to low-line OCP (as well

as low-line frequency slide) only after 3 consecutive half-line cycle

peak values that are below the low-line threshold V

HIGH-. In the event

of a line drop-out, the controller may revert from high-line to low-line

set-points if the drop-out exceeds 37 ms (nominal).

A follower-mode feature updates the controller to high-line status

rapidly, as soon as the input voltage exceeds V

HIGH+. This feature has

particular benefit for high-line hard-start conditions after a long AC

line drop-out where the peak detector may initially indicate a low

input line condition.

PI-7255-031022

~170 VAC

~140 VAC

OCP(LL)

OCP(HL)

Safe Operating (SOA) mode

Since the cycle-by-cycle OCP mechanism described above does not

prevent the possibility of inductor current ‘stair-casing’, and an SOA

mode is also featured.

Rapid build-up of the switch current can occur in the event of

inductor saturation or when the input and output voltage differential

is small resulting in too little inductor reset time.

The SOA mode is triggered whenever the switch current reaches

current limit (I

OCP) and the on-time is less than tSOA. The SOA mode

forces an off-time equal to t

OFF(SOA) and pulls the internal error-voltage

E) down by 1/2 of its maximum value in order to ensure the switch

remains within its SOA.

Fast Output Voltage Overvoltage Protection

The HiperPFS-5 features a voltage feedback threshold comparator on

the FEEDBACK pin which detects an output overvoltage condition to

allow rapid response, (independent of the COMPENSATION pin

response), to prevent hazardous voltage conditions from occurring.

The overvoltage protection is hysteretic – the voltage on the

FEEDBACK pin must drop by 0.1 V (equating to an output voltage

drop of 10 V) before switching is re-started.

FEEDBACK to COMPENSATION Pin Short Detection Safeguard

The PFC controller continuously monitors the FEEDBACK and

COMPENSATION pins to ensure that there are no potential short

conditions between the adjacent FEEDBACK and COMPENSATION

pins, which could result in output overvoltage conditions. In the

event a potential short is detected, a rapid short check is performed

and a shutdown is executed in the event that a suspected short is

validated.

Open FEEDBACK Pin Protection

The FEEDBACK pin continuously sinks a static current of I

FBPD

([VCC >VCC

UVLO+]) to protect against a fault related to an open

FEEDBACK pin or invalid feedback divider network. The internal

current sink introduces a small static offset to the output regulation

which can be accounted for in selecting the output feedback

regulation components (FEEDBACK pin divider).

Hysteretic Thermal Protection

The thermal shutdown circuit senses the controller die temperature

which is well coupled to the power switch through the exposed,

source pad and PCB copper cooling plane. The OTP (over-

temperature protection) threshold is set at 138 °C typical with 36 °C

hysteresis.

When the controller die temperature rises above this threshold (OTP),

the controller initiates a soft-shutdown and remains disabled until the

controller die temperature falls by ~36 °C, at which point the device

will re-initiate the start-up sequence.

Figure 13. Line Dependent OCP.

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