BL8305A

BL8305A

BL8305A

BALLAST CONTROL IC

BALLAST CONTROL IC

BALLAST CONTROL IC

http://www.belling.com.cn

- 6 -

8/28/2006

Total 8 Pages

Driving MHF the output connection is shows as the figure above. The driving

voltage is coupled from out1 by a 1:2 transformer in order to separate the IC

form high voltage. In MHF driving configuration, HV is connect to GND directly,

hence whether the BL8305A in preheat, ignition or run mode the output of BL8305A

is fixed.

Fault Protection

Fault Protection

Fault Protection

Fault Protection

The BL8305A provides 3 leads to sensing fault: Pro (PIN9), FD (PIN10) and LD

(PIN11).

The Pro PIN is enabled at the IC turns on. Once the voltage at this pin exceeds

Vpro (0.55V), the IC enters fault mode and both outputs are latched in the ‘low’

state.

The FD PIN is used for filament detection; the IC will be restart when FD received

a pulse.

LD is a window discriminator. The high threshold

is 4.3V, and the low threshold is 2.0V. LD has a pull

up resistor 200K to Vdc, and a pull down resistor 200K

to GND, in order to get a bias voltage 3.2V for the LD

PIN. At the end of ignition mode, LD will become

effective after 1s delay(1s delay is used for avoid

ignition’s burr).

Once the BL8305A enters the fault mode, the IC will

lock the state until VCC recycles back below the shut

down threshold or the filament detection PIN, SD, receives a pulse.