ml4836 Microsemi Corporation, ml4836 Datasheet - Page 9

• Manufacturer Part Number: ml4836
• Description: Compact Fluorescent Electronic Dimming Ballast Controller
• Manufacturer: Microsemi Corporation

FUNCTIONAL DESCRIPTION
and
The oscillator’s minimum frequency is set when I
where:
The oscillator's start frequency can be expressed by:
Both equations assume that t
When LFB OUT is high, I
frequency occurs. The charging current varies according to
two control inputs to the oscillator:
t
CHG
1. The output of the preheat timer
F
F
F
OSC
=
START
MIN
R C In
T
=
Figure 8. Typical V
t
T
0 54
CHG
.
0 54
.

 
1
+
1
V
V
R C
REF
t
REF
T
2
DIS
R R
T
T
+
+
1
II
I
CHG
CHG
T
CHG
the Rectified AC Line and Bootstrapped from an Auxiliary Winding.
2
7
CC
CHG
´
´
= 0 and the minimum
C
R
R
T
and I
T
V
T
I
CC
CC
>> t
-
-
0.34mA
V(OFF)
V(ON)
5.5mA
V
V
V CC Z
CC
TL
TH
DIS
Waveforms when the ML4836 is Started with a Bleed Resistor from
.
(Continued)
CHG
= 0
(5a)
(3)
(4)
(5)
In preheat condition, charging current is fixed at
In running mode, charging current decreases as the
voltage rises from 0V to V
The charging current behavior can be expressed as:
The highest frequency is attained when I
which is attained when voltage at LFB OUT is at 0V:
Highest lamp power, and lowest output frequency are
attained when voltage at LFB OUT is at its maximum
output voltage (V
2. The voltage at LFB OUT (lamp feedback amplifier
output)
I
I
CHG
CHG
I
( ) 0
CHG PREHEAT
=
=
R
5
(
SET
R
V
SET
5
t
t
-
OH
8
k
)
).
LEAO
=
±
R
25%
25
SET
.
OH
at the LAMP FB amplifier.
(6)
CHG
ML4836
is highest,
(7)
(8)
9