BL8305A

BL8305A

BL8305A

BALLAST CONTROL IC

BALLAST CONTROL IC

BALLAST CONTROL IC

http://www.belling.com.cn

- 4 -

8/28/2006

Total 8 Pages

FUNCTION DESCRIPTION

FUNCTION DESCRIPTION

FUNCTION DESCRIPTION

FUNCTION DESCRIPTION

Start

Start

Start

Start-

--

-up and Power Supply

up and Power Supply

up and Power Supply

up and Power Supply

When the VCC is below the turn-on threshold of the IC, the BL8305A is in the

low power consumption mode, oscillator and half-bridge are shut off. The start-up

capacitor (C1) is charged by 400V DC-BUS

through resistor (Rstart). The charge current

(Icharge) is the current through Rstart minus

the start-up current (IQstart) drawn by the

IC. So the choice basis of starting resistance

Rstart is: In most abominable cases, the

current guaranteeing to pass Rstart is

IQStart of twice at least.

Once the capacitor voltage on VCC reaches the start-up threshold, the IC turns

on and the output turns on. The rectified current charges the capacitor at about

15V. The recommended capacitor value is 22uF.

Preheat Mode, Ignition Mode and Run Mode

Preheat Mode, Ignition Mode and Run Mode

Preheat Mode, Ignition Mode and Run Mode

Preheat Mode, Ignition Mode and Run Mode

The Preheat frequency, preheat time and run mode frequency of BL8305A are all

programmable by external components. The typical frequency vs. time curve is as

the picture shows.

The preheat time is set by the external capacitor Cp. An internal current source

ICpreCharge charges Cp when the IC

started. The frequency remains at

eh preheat frequency until the

voltage on Cp over the threshold

voltage. After preheat the BL8305A

begins to igniting the lamp. The

total

preheat

time

is: