EFS

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5/ THE DRIVER: FUNCTIONAL DESCRIPTION

GND

G1

G2

Preheat

Select

Vcc

Shunt

State

tube

Minimum

Power supply

State tube detection

(Striked / Off)

0 current synchro

ISO synchro

350mA

Pre-heat

period

counter

1,5s

or

2.5s

Current generator

30mA

8 attempts

Strikes counter

UVLO

Clock 1/8

EFS2A DRIVER Internal block diagram (50Hz operation)

ALGORITHM

1. At switch on:

At switch on, an integrated Under Voltage Lock Out function (UVLO) resets the driver as long as the supply

voltage stays below a safety level.

2. Preheat:

The ignition sequence begins with the preheat

phase. Two different duration’s can be selected with

PIN 2 (see table EFS STARLIGHT-KIT PARTS

SELECTION page 2).

During this phase, the driver maintains the ASD

™ in

a full ON-state making the starter equivalent to a

bi-directional conducting switch.

3. Ignition of the fluorescent tube:

At the end of the preheat period, the starter strikes

the fluorescent lamp.

For that, the driver reads continuously the current

through the starter. When the current reaches the

the ASD

™. This induces a high voltage pulse across

the lamp. This pulse amplitude is limited by the

ASD

™ (′1350V).

4. If the lamp fails to strike:

The driver detects the state of the tube (lit or off). If it

stays off during 8 mains cycles (loop 1), a new

preheat period, shorter than the first one, starts

again (loop 3), followed by a new ignition attempt.

The driver will try to fire the tube 8 times. If none of

the 8 attempts succeeds in striking the lamp, the driver turns in standby mode, and the whole starter is fully

stopped until the next mains removal and power supply reset.

5. If the lamp is ignited:

If the lamp is ignited, the driver stays in standby mode while monitoring the state of the lamp (loop 2).

During normal operation of the tube, this short pulse is masked by the lamp conduction. If the mains

interruption is really long enough to turn off completely the lamp, a new ignition sequence starts again (loop

3) with 8 other new possible attempts.

AC MAINS ON

UVLO

RESET

Preheat *

1.5s or 2.5s

Strike

Attempt = Attempt + 1

Preheat *

0.75s or 1.25s

Attempt <8

YES

YES

YES

NO

NO

NO

Loop 3

Loop 2

Tube

Ignited?

Fail = Fail + 1

Fail = 8

Fail = 0

Autosupply

Autosupply

Fail = 0

Attempt = 0

* see the preheat duration table § 6

Loop 1