During the burst-mode sleep phase, the HS BOOT capacitor discharges. The burst packets always start with a

LVG pulse to recharge the bootstrap capacitor. A fast external bootstrap diode is necessary.

9.4

PFC control and fault management

9.4.1

PFC resources

Table 5. Related pins

Pin name

Description

Level

Function

PFC_CS

PFC MOSFET current sense

0 - 125 mV

6-bit ramp enhanced COT feature

500 mV

OCP1

900 mV

OCP2 fault

PFC_ZCD PFC auxiliary connection for ZCD detection

-

-

PFC_FB Reading for PFC Vout estimation

ADC, 10 bits

-

VAC

Mains line voltage reading

ADC, 10 bits

-

PFC_GD PFC MOSFET gate-driver

-

-

9.4.2

Vin reading

Input line voltage peak (Vin) reading on the VAC pin by the ADC at the AC line peak.

9.4.3

PFC output voltage feedback reading

PFC output voltage reading on the PFC_FB pin by the ADC.

9.4.4

PFC OVP comparator

The PFC OVP comparator sets the limit for the PFC output voltage. It monitors the PFC_FB pin with respect to a

fixed 2.3 V threshold.

9.4.5

PFC RECOT comparator

The PFC RECOT comparator implements the TON adjustment for the ramp enhanced constant on-time (RECOT)

control.

It monitors the PFC_CS pin with respect to a programmable threshold. Its output communicates to the PFC

SMED.

9.4.6

PFC OC1 comparator

The PFC OC1 comparator sets the limit for the operational maximum allowed peak current into the PFC

MOSFET. If the OC1 threshold is hit the PFC_GD is turned off. This protection works cycle by cycle.

It monitors the PFC_CS pin with respect to a fixed 500 mV threshold. Its output communicates to the PFC SMED.

9.4.7

PFC OC2 comparator

The PFC OC2 comparator sets an HW limit for the current flowing into the PFC MOSFET: it triggers the OCP

fault.

It monitors the PFC_CS pin with respect to a fixed 900 mV threshold.

9.4.8

PFC ZCD

The PFC ZCD comparator performs the zero cross detection to implement the soft switching of the PFC

MOSFET.

It monitors the PFC_ZCD pin with respect to two programmable rising and falling thresholds.

Its output communicates to the PFC SMED.

STNRG011

PFC control and fault management

DS12075 - Rev 4

page 16/31