L6567 datasheet(5/15 Pages) STMICROELECTRONICS

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L6567

(*) Before starting the first commutation; when switching 6V is guaranteed.

General operation

The L6567 uses a small amount of current from a supply resistor(s) to start the operation of the IC. Once start

up condition is achieved, the IC turns on the lower MOS transistor of the half bridge which allows the bootstrap

capacitor to charge. Once this is achieved, the oscillator begins to turn on the upper and lower MOS transistors

at high frequency, and immediately ramps down to a preheat frequency. During this stage, the IC preheats the

lamp and after a predetermined time ramps down again until it reaches the final operating frequency. The IC

monitors the current to determine if the circuit is operating in capacitive mode. If capacitive switching is detected,

the IC increases the output frequency until zero-voltage switching is resumed.

Startup and supply in normal operation

At start up the L6567 is powered via a resistor connected to the RHV pin (pin 13) from the rectified mains. The

current charges the CS capacitor connected to the VS pin (pin 5). When the VS voltage reaches the threshold

VSLOW1 (max 6V), the low side MOS transistor is turned on while the high side one is kept off. This condition

assures that the bootstrap capacitor is charged. When VS HIGH1 threshold is reached the oscillator starts, and

the RHV pin does not provide anymore the supply current for the IC (see fig.1).

G2DON

On Delay of G2 Output

1.05

1.4

1.75

µs

Ratio between Delay Time +

Conduction Time of G1 and G2

IRHV = 1mA; Cl = 5V

Cl = 0V

0.87

0.77

1.15

1.30

LOW SIDE DRIVER SECTION

Ron G2 so

G2 Source Output Resistance

VS = 12V, V = 3V

190

Ω

Ron G2 si

G2 Sink Output Resistance

VS = 12V, V = 3V

125

Ω

Ron G1 so

G1 Source Output Resistance

VS = 10V, V = 3V

190

Ω

Ron G1 si

G1 Sink Output Resistance

VS = 10V, V = 3V

125

Ω

HIGH SIDE DRIVER SECTION

IFSLK

Leakage Current of FS PIN to

GND

VFS = 568V; G1 = L

VFS = 568V; G1 = H

µA

IS1 LK

Leakage Current of S1 PIN to

GND

VS1 = 568V; G1 = L

VS1 = 568V; G1 = H

µA

BOOTSTRAP SECTION

Boot Th

BOOTSTRAP Threshold

VS = 10.6V before turn on

5 (*)

AVERAGE RESISTOR

RAVERAGE

Average Resistor

38.5

Ω

Symbol

Parameter

Test Conditio n

Min.

Typ.

Max.

Unit

DON

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ELECTRICAL CHARACTERISTCS (Continued)

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