Application information

L6382D

12/22

6

Application information

6.1

Power management

The L6382D has two stable states (SAVE MODE and OPERATING MODE) and two

additional states that manage the Start-up and fault conditions (Figure 10): the Over Current

Protection is a parallel asynchronous process enabled when in operating mode.

Following paragraphs will describe each mode and the condition necessary to shift between

them.

Figure 10. State diagram

6.1.1

START-UP mode

With reference to the timing diagram of figure 11, when power is first applied to the

converter, the voltage on the bulk capacitor builds up and the HV generator is enabled to

operate drawing about 10mA. This current, diminished by the IC consumption (less than

150

µA), charges the bypass capacitor connected between pin Vcc and ground and makes

its voltage rise almost linear.

During this phase, all IC's functions are disabled except for:

●

the current sinking circuit on VREF pin that maintains low the voltage by keeping

disabled the microcontroller connected to this pin;

●

the High-Voltage Start-Up (HVSU) that is ON (conductive) to charge the external

capacitor on pin Vcc.

As the Vcc voltage reaches the start-up threshold (14V typ.) the chip starts operating and

the HV generator is switched off.

SAVE MODE

OPERATING

MODE

SHUT DOWN

V

V

V

&

T

LGI low

for more

than 100

µs

START-UP

V

or

V

V

V