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參數資料
| 型號： | ML4832 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Electronic Dimming Ballast Controller(電子調光整流器控制器) |
| 中文描述： | 電子調光鎮(zhèn)流器控制器（電子調光整流器控制器） |
| 文件頁數： | 9/15頁 |
| 文件大?。?/td> | 151K |
| 代理商： | ML4832 |
ML4832
REV. 1.0 10/12/2000
9
In running mode, charging current decreases as the V
PIN6
rises from 0V to V
OH
of the LAMP FB amplifier. The
highest frequency will be attained when I
CHG
is highest,
which is attained when LFB OUT is at 0V:
I
R
CHG
SET
( )
5
=
(7)
Highest lamp power, and lowest output frequency are
attained when LFB OUT is at its maximum output voltage
(V
OH
).
In this condition, the minimum operating frequency of the
ballast is set per (5) above.
For the IC to be used effectively in dimming ballasts with
higher Q output networks a larger C
T
value and lower R
T
value can be used, to yield a smaller frequency excursion
over the control range (V
LFB OUT
). The discharge current is
set to 5.5mA. Assuming that I
DIS
>> I
RT
:
t
C
DIS VCO
(
T
)
×
600
(8)
IC BIAS, UNDER-VOLTAGE LOCKOUT AND THERMAL
SHUTDOWN
The IC includes a shunt regulator which will limit the
voltage at V
CC
to 15V (V
CCZ
). The IC should be fed with
a current limited source, typically derived from the ballast
transformer auxiliary winding. When V
CC
is below
V
CCZ
– 1.1V, the IC draws less than 0.48mA of quiescent
current and the outputs are off. This allows the IC to start
using a “bleed resistor” from the rectified AC line.
To help reduce ballast cost, the ML4832 includes a
temperature sensor which will inhibit ballast operation if
the IC’s junction temperature exceeds 120°C. In order to
use this sensor in lieu of an external sensor, care should be
taken when placing the IC to ensure that it is sensing
temperature at the physically appropriate point in the
ballast. The ML4832’s die temperature can be estimated
with the following equation:
T
T
P
C
W
J
A
D
×
×
°
65
/
(9)
STARTING, RE-START, PREHEAT AND INTERRUPT
The lamp starting scenario implemented in the ML4832
is designed to maximize lamp life and minimize ballast
heating during lamp out conditions.
The circuit in Figure 7 controls the lamp starting scenarios:
Filament preheat and lamp out interrupt. C
X
is charged
with a current of I
RSET
/4 and discharged through R
X
. The
voltage at C
X
is initialized to 0.7V (V
BE
) at power up. The
time for C
X
to rise to 4.8V is the filament preheat time.
During that time, the oscillator charging current (I
CHG
) is
2.5/R
SET
. This will produce a high frequency for filament
preheat, but will not produce sufficient voltage to ignite
the lamp.
After cathode heating, the inverter frequency drops to
F
MIN
causing a high voltage to appear to ignite the lamp.
If the voltage does not drop when the lamp is supposed to
have ignited, the lamp voltage feedback coming into pin 9
rises to above V
REF
, the C
X
charging current is shut off and
the inverter is inhibited until C
X
is discharged by R
X
to the
1.2V threshold. Shutting off the inverter in this manner
prevents the inverter from generating excessive heat when
Figure 6. Typical VCC and ICC Waveforms when
the ML4832 is Started with a Bleed Resistor from
the Rectified AC Line and Bootstrapped from an
Auxiliary Winding.
Figure 7. Lamp Preheat and Interrupt Timers
FUNCTIONAL DESCRIPTION
(Continued)
VCCZ
V
ON
V
OFF
5.5mA
0.34mA
V
CC
I
CC
t
t
10
9
R
X
C
X
6.8
+
–
1.2/4.8
HEAT
INHIBIT
0.625
R
SET
+
–
1.2/6.8
–
+
V
REF
DIMMING
LOCKOUT
R
X
/C
X
INT
Q
R
S
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ML4832CP | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML4832CS | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Electronic Dimming Ballast Controller |
| ML4833 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:帶功率因數校正的調光電子鎮(zhèn)流器控制器ML4833 |
| ML4833CP | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Electronic Dimming Ballast Controller |
| ML4833CS | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Electronic Dimming Ballast Controller |
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