EFS

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In order to reduce the number of components, an

auxiliary power supply is integrated in the ASD

™.

This active power supply works directly on the

mains and requires only a low voltage capacitor

16V - 22

µF. The operating mode of this supply

varies with the starter operating phase:

4/ AUXILIARY POWER SUPPLY:

DRIVER

ASD

VCC

G1

GND

TUBE

C SUPPLY

7.57

7.68

D1

R1

R2

R6

POWER SUPPLY SCHEMATIC

Supply operation during preheat phase:

During preheat phase, the driver manages alone the supply function (neither the driver nor D1 and R6 are

involved). A part of the current flowing through the ASD

™ is used, at the beginning and at the end of each

positive mains half cycle, to charge the output capacitor.

Supply operation during standby phase:

When the lamp is lit, the monitors its supply voltage (Vcc). At the beginning of each positive mains half

cycle, when Vcc is lower than 7.57V, the driver closes the ASD

™ supply switch. The capacitor is charged

to provide the standby current of the driver. During this phase the tube lamp is short circuited by the

ASD

™. When the supply voltage reaches 7.68V, the driver opens the ASD™ supply switch. Since this

current is also flowing in the ballast, the supply turn off provides across the lamp an additional voltage

spike. After running few minutes the lamp becomes warm and this spike voltage naturally decreases.

SUPPLY DURING PREHEAT PHASE

Starter current

Starter voltage

at the ignition

5min after

ignition

SUPPLY DURING STANDBY PHASE

(Without E.M.I. Capacitor nor R6 nor D1)

To reduce dramatically this repetitive voltage spikes across the lamp, the R6 resistor with the diode D1

provide a part of the supply current. Thus, the ripple voltage of the supply voltage is reduced, as well as the

level of the switched off current. On the other hand, this increases the safety margin of the RF noise

(versus the IEC 55015 limits)