Device block description

AN993

12/27

Doc ID 5656 Rev 10

3.2

Control section

The L6574 has two control functions, EN1 and EN2. Both functions are active high. To fully

understand how these functions work, refer to Figure 9 and Figure 10.

●

EN1 (latched enable) is dedicated to stopping all device functions and is usually

activated when a strong fault is detected (for example, when the lamp is disconnected).

This status can be cancelled in two different ways: either by reducing the supply voltage

below its minimum threshold, or by activating the second control pin EN2 (EN2

overrides EN1). When the device restarts, the start-up sequence is reactivated.

●

EN2 (repeating startup) is dedicated to restarting the preheating and ignition

procedure; it is normally activated when the application fails to ignite the lamp. When

EN2 is activated the starting procedure restarts. The L6574 operates to the maximum

frequency all the while that EN2 remains active.

Figure 9.

Controls timing diagram

AM01318v1

LVG

EN1

VSupply

Time

Forced restart

HVG

Latched enable

EN2