6.2.5

Deep low consumption mode

This state is intended to reduce the IC consumption to the minimum level in order to reduce the input power

consumption during burst-mode condition (FB or OPTO driven).

When the deep low consumption mode condition is removed, the system evolves to the relevant next state

without turning on the high-voltage startup unit.

6.2.6

Auto-restart time and check state

These are auxiliary states. Auto-restart time is intended to maintain the device supplied for a time equal to TART

until a new restart procedure is automatically generated.

If VCC drops below VCC-OFF, the timers are frozen, while if VCC drops below VCC-SHD the internal logic of the

device is reset and all automatic procedures are also interrupted.

The check state is a logic state that is invoked after VCC-ON trigger to check the status of all protections and take

the proper actions according to protection logic.

6.3

Control loop

The HVLED101 IC is optimized to operate as high power factor peak current mode quasi-resonant (QR) flyback

(Figure 7). In order to realize this operating scheme, it embeds a multiplier that creates the threshold for the PWM

comparator that turns off the main switch when the current measured across a shunt resistor, placed between the

source of said switch and GND, reaches the above-mentioned threshold.

During QR operation, the turn-on command is given by an internal logic that detects the falling edge subsequent

to the transformer demagnetization and applies the delay time programmed by the resistance connected to

DLY/CFG pin.

A minimum off-time (TBLANK) is provided to ignore the falling edges that could be associated with spurious

oscillations of leakage inductance.

Figure 7. QR operating scheme

GD

TBLANK

ZCD

TDLY

CS

VCS

VTRIG

VARM

GD

ZCD

CS

unarmed

already triggered

VTRIG

VARM

VCS

TBLANK

TDLY

TWAIT

The IC operates in quasi-resonant mode, but one or more resonance valley can be skipped to slow down the

operating frequency and improve the system efficiency. The VL pin can be used to adjust the valley skipping

levels as described in the relevant paragraph.

During fixed frequency operation, the turn-on command is given by an internal logic.

HVLED101

Control loop

DS14143 - Rev 2

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