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HVLED001

Application information

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7.4.1

VCC supply management

The IC is designed to operate with a range of supply voltage to ensure an optimum gate

driving. An active limiting device is embedded to prevent low energy fluctuations to bring the

VCC voltage above the technological constraints.

Both the active mode and the low consumption mode exhibits very low supply currents in

order to meet energy saving regulation.

The VCC pin can be driven independently from the HVSU pin's connection, for example

when auxiliary supply voltage is present. In this case the HVSU pin will be used solely to

monitor input voltage.

A bulk capacitor, having a capacitance of around 10 µF, followed by a ceramic capacitor,

necessary to properly sustain the Vcc voltage during all operating phases.

7.4.2

High voltage start-up

High voltage start-up (HVSU) circuitry is primarily intended to provide the start-up current to

the VCC pin and maintain the IC responsive during low consumption modes.

This structure is able to sustain at least 800 V to avoid any damage in case of a surge or

a burst on the stage's input.

The overall structure is off until input voltage reaches the VHVSU, start threshold, after that

it sources a minimum current (Icharge,su) to charge the VCC pin up to Vcc,su threshold.

This condition prevents the IC from severe damaging effects in case of a short-circuit on the

threshold. At this occurrence the active mode is invoked and the HVSU is turned off.

During other active mode's phases and the stop mode the HVSU is off.

If the low consumption mode is entered, the HVSU unit is turned on.

Table 6 summarizes the HVSU behavior in all IC conditions.

Table 6. HVSU operating modes

Operating condition (see Figure 7)

VCC range

OFF Icharge,su Icharge

All states if VIN < VHVSU,ON

-

X

Start-up (logic start-up)

0 V

X

Start-up (IC start-up)

Vcc,su

X

Active mode (no switching period)

Vcc,su

X

Active mode (switching period)

Vcc,su

X

Stop mode

Vcc,su

X

Low consumption mode

Vcc,su Vcc,on (rising)

X

Low consumption mode (after the end of entering conditions)

Vcc,su

X