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ML4821IP 参数 Datasheet PDF下载

ML4821IP图片预览
型号: ML4821IP
PDF下载: 下载PDF文件 查看货源
内容描述: 功率因数控制器 [Power Factor Controller]
分类和应用: 光电二极管控制器
文件页数/大小: 12 页 / 180 K
品牌: MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
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May 1997
Micro Linear
GENERAL DESCRIPTION
The ML4821 provides complete control for a “boost” type
power factor correction system using the average current
sensing method. Special care has been taken in the design
of the ML4821 to increase system noise immunity. The
circuit includes a precision reference, gain modulator,
average current error amplifier, output error amplifier,
over-voltage protection comparator, shutdown logic, as
well as a high current output. In addition, start-up is
simplified by an under-voltage lockout circuit.
In a typical application, the ML4821 controls the AC input
current by adjusting the pulse width of the output
MOSFET. This modulates the line current so that its shape
conforms to the shape of the input voltage. The reference
for the current regulator is a product of the sinusoidal line
voltage times the output of the error amplifier which is
regulating the output DC voltage. Average line voltage
compensation is provided in the gain modulator to ensure
constant loop gain over a wide input voltage range. This
compensation includes a special “brown-out” control
which reduces output power below 90V RMS input.
ML4821*
Power Factor Controller
FEATURES
s
s
s
s
s
s
s
s
s
Average current sensing for lowest possible
harmonic distortion
Average line compensation with brown-out control
Precision buffered 5V reference
1A peak current totem-pole output drive
Overvoltage comparator eliminates output “runaway”
due to load removal
Wide common mode range in current sense
comparators for better noise immunity
Large oscillator amplitude for better noise immunity
Output driver internally limited to 17V
“Sleep mode” shutdown input
* Some Packages Are Obsolete
BLOCK DIAGRAM
11
1
OVP
I
LIM
V
REF
+
0.7V
+
+
SLEEP
UNDER
VOLTAGE
LOCKOUT
V
REF
16
2
3
IA OUT
IA–
GND
18
+
R
S
Q
V
LIMIT
17V
V
CC
15
IA+
4
+
OUT
14
5
8
I
SINE
V
RMS
OUT
GAIN
MODULATOR
PGND
R
T
OSC
SYNC
C
T
V
REF
13
12
10
17
6
7
EA OUT
EA–
V
REF
SOFT START
+
9
Micro Linear
1