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ML4802IS 参数 Datasheet PDF下载

ML4802IS图片预览
型号: ML4802IS
PDF下载: 下载PDF文件 查看货源
内容描述: PFC / PWM控制器组合与绿色模式 [PFC/PWM Controller Combo with Green Mode]
分类和应用: 功率因数校正光电二极管控制器
文件页数/大小: 15 页 / 300 K
品牌: MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
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August 2000
PRELIMINARY
ML4802
PFC/PWM Controller Combo with Green Mode
GENERAL DESCRIPTION
The ML 4802 is a controller for power factor corrected,
switched mode power supplies that offers Green Mode
operation and reduced start-up and operating currents.
Green Mode is an efficiency improving circuit feature
which operates automatically in low power situations.
This feature helps meet the demands of Energy Star™
programs.
Power Factor Correction (PFC) offers the use of lower cost
bulk capacitors, reduces power line loading and stress on
the switching FETs. The ML4802 includes circuits for the
implementation of a leading edge, average current,
“boost” type power factor corrector and a trailing edge
Pulse Width Modulator (PWM).
The PFC frequency of the ML4802 is automatically
synchronized to be one half that of the PWM. This
technique allows the user to design with smaller PWM
components while maintaining the optimum operating
frequency for the PFC. An over-voltage comparator shuts
down the PFC section in the event of a sudden decrease
in load. The PFC section also includes peak current
limiting and brown-out protection.
s
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FEATURES
Internally synchronized PFC and PWM in one IC
Green Mode maximizes efficiency during low power
standby operation
Low supply current
(Start-up 200µA typ., operating 5.5mA typ.)
Average current continuous boost leading edge PFC
High efficiency trailing edge PWM can be configured
for current mode operation
Reduced ripple current in the storage capacitor
between the PFC and PWM sections
PFC overvoltage comparator eliminates output
“runaway” due to load removal
Current fed gain modulator for improved noise
immunity
Overvoltage protection, UVLO, and soft start
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s
s
s
s
s
s
BLOCK DIAGRAM
VEAO
16
IEAO
1
POWER FACTOR CORRECTOR
+
VCC
13
VEA
VFB
15
2.5V
IAC
VRMS
ISENSE
RAMP 1
2
4
3
8
GAIN
MODULATOR
1.8kΩ
-
+
1.8kΩ
+
IEA
PFC
CONTROLLER
8V
2.75V
-
OVP
7.5V
REFERENCE
14 VREF
-1V
+
-
PFC ILIMIT
PFC
OUTPUT
DRIVER
12 PFC OUT
÷2
VFB
OSCILLATOR
DC LIMIT
VDC
GREEN
MODE
CONTROLLER
RT/CT 7
RAMP 2
9
8V
VLS
1.25V
-
GREEN
MODE
VDC
6
VCC
25µA
+
VIN OK
-
+
DC ILIMIT
+
VFB
2.43V
-
+
SS
5
8V
1.5V
-
PWM
OUTPUT
DRIVER
11 PWM OUT
PULSE WIDTH MODULATOR
1