L6382D(2005) データシートの表示（PDF） - STMicroelectronics

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L6382D
(Rev.:2005)

POWER MANAGEMENT UNIT FOR MICROCONTROLLED BALLAST

STMicroelectronics 

L6382D

4 APPLICATION INFORMATION

4.1 POWER MANAGEMENT

The L6382D has two stable states (save mode and operating mode) and two additional states that man-

age the Start-up and fault conditions (fig. 5): the Over Current Protection is a parallel asynchronous pro-

cess enabled when in operating mode.

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

Figure 5.

START-UP

VCC<VREF(OFF)

VCC>VCC(ON)

VCC<VREF(OFF)

SAVE MODE

VCC<VCC(ON)

SHUT DOWN

VREF>3V

&

TDE>10ms

LGI low

for more

than 100ms

OPERATING

MODE

VCC < VCC(OFF)

or

VREF<2V

4.1.1 START-UP mode

With reference to the timing diagram of figure 6, 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 cur-

rent, diminished by the IC consumption (less than 150µA), charges the bypass capacitor connected be-

tween 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.

Summarizing:

■ the high-voltage start-up generator is active;

■ VREF is disabled with additional sinking circuit on pin VREF is enabled;

■ TPR is disabled;

■ OCP is disabled;

■ the drivers are disabled.

4.1.2 SAVE Mode

This mode is entered after the Vcc voltage reaches the turn-on threshold; the VREF is enabled in low cur-

rent source mode to supply the µC connected to it, whose wake-up required current must be less than

10mA: if no switching activity is detected at LGI input, the high voltage start-up generator cycles ON-OFF

keeping the Vcc voltage between VccON and VccSM.

8/14

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