ml4833 Microsemi Corporation, ml4833 Datasheet - Page 10

• Manufacturer Part Number: ml4833
• Description: Electronic Dimming Ballast Controller
• Manufacturer: Microsemi Corporation

ML4833
LFB OUT is ignored by the oscillator until C
6.8V threshold. The lamps are therefore driven to full
power and then dimmed. The C
about 7.5V.
10
R
X
DIMMING
LOCKOUT
INHIBIT
C
X
Figure 8. Lamp Preheat and Interrupt Timers
R
HEAT
X
INT
/C
>1.25
X
R
6.8
4.8
1.2
.65
X
9
/C
0
8
INTERRUPT
X
1.25V
6.8
–
+
0.625
R
1.2/4.8
1.2/6.8
SET
X
pin is clamped to
+
+
–
–
Figure 9. Lamp Starting and Restart Timing
X
reaches
R
S
Q
HEAT
DIMMING
LOCKOUT
INHIBIT
A summary of the operating frequencies in the various
operating modes is shown below.
TYPICAL APPLICATIONS
Figure 10 shows a schematic for a dimming power-factor
corrected 60W ballast, designed to operate two F32T8
fluorescent lamps connected in series.
Operating Mode
Dimming
Dimming
Lock-out
Preheat
Control
Operating Frequency
[F(MAX) to F(MIN)]
F(MIN) to F(MAX)
F(MIN)
2