6

Application information

6.1

Typical application

The HVLED101 high power factor flyback controller is suitable to operate either as a single-stage high power

factor (HPF) flyback controller or as a DC/DC flyback controller in a two-stage application with front-end PFC

converter. The control can be primary side (PSR) or secondary side (SSR). Application schematics of the two

control types are reported in Figure 2 and Figure 3.

6.2

Operating modes

The IC presents various operating modes, described in the following sections. Figure 5 shows the operation

during initial startup phase.

Figure 5. Initial startup phase

VHVSU

VCC-ON

ICHG-H

ICHG-L

VHV-START

ICC

ICC-START-UP

Start-up

Ramp-up

Low Cons.

ICC-LC

ICHG

VCC

ICC

VFLT-ON

FAULT

switching

activity

OPTO

VZCD S&H

PROG

Reading

VBM

VUVP

VCS-RU

FB, VL

Active mode

VCC-LOW

6.2.1

Startup phase

As soon as HVSU pin voltage reaches VHV-START, the high-voltage startup unit is turned on to charge the VCC

capacitor.

The charging current is limited to ICHG-L until VCC voltage reaches VCC-LOW threshold, and then it is toggled to a

higher charging current (ICHG-H) to minimize the startup time.

Once the VCC reaches VCC-ON threshold, the DLY/CFG pin is read to set the configuration of input voltage

protections and input voltage range.

HVLED101

Application information

DS14143 - Rev 2

page 13/36