Application information

HVLED001A

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7.3.2

High voltage startup

The high voltage startup (HVSU) circuitry is primarily intended to provide the startup 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

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 the Vcc,su threshold.

pin.

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 7 summarizes the HVSU behavior in all IC conditions.

7.4

Auto-restart timer (ART)

The auto-restart timer unit is responsible for the generation of the protection intervals and of

the restart times after the low consumption mode. A summary of all possible combinations

of times is described in Section 7.5.

Table 7. HVSU operating modes

Operating condition (see Figure 7)

VCC range

OFF Icharge,su Icharge

All states if VIN < VHVSU,ON

-

X

Startup (logic startup)

0 V … Vcc,su

X

Startup (IC startup)

Vcc,su … Vcc,on

X

Active mode

Vcc,su … VCC,MAX

X

Stop mode

Vcc,su … VCC,MAX

X

Low consumption mode

Vcc,su Vcc,on (rising)

X

Low consumption mode

(after the end of entering conditions)

Vcc,su … Vcc,on

X