參數(shù)資料
型號： ML4803CP1
廠商： Fairchild Semiconductor Corporation
元件分類： 基準電壓源/電流源
英文描述： 8-Pin PFC and PWM Controller Combo
中文描述： 8引腳PFC和PWM組合控制器
文件頁數(shù)： 7/13頁
文件大?。?/td> 195K
代理商： ML4803CP1
ML4803
7
February 1999
REF
EA
–
+
–
+
OSC
DFF
R
D
Q
Q
CLK
U1
RAMP
CLK
U4
U3
C1
RL
I4
SW2
SW1
+
DC
I1
I2
I3
VIN
L1
VEAO
CMP
U2
RAMP
VEAO
TIME
VSW1
TIME
Figure 3. Typical Leading Edge Control Scheme.
current will ramp up. The effective duty cycle of the
trailing edge modulation is determined during the ON
time of the switch. Figure 2 shows a typical trailing edge
control scheme.
In the case of leading edge modulation, the switch is
turned OFF right at the leading edge of the system clock.
When the modulating ramp reaches the level of the error
amplifier output voltage, the switch will be turned ON.
The effective duty-cycle of the leading edge modulation is
determined during the OFF time of the switch. Figure 3
shows a leading edge control scheme.
One of the advantages of this control technique is that it
requires only one system clock. Switch 1 (SW1) turns OFF
and Switch 2 (SW2) turns ON at the same instant to
minimize the momentary
“
no-load
”
period, thus lowering
ripple voltage generated by the switching action. With
such synchronized switching, the ripple voltage of the first
stage is reduced. Calculation and evaluation have shown
that the 120Hz component of the PFC
’
s output ripple
voltage can be reduced by as much as 30% using this
method, substantially reducing dissipation in the high-
voltage PFC capacitor.
TYPICAL APPLICATIONS
ONE PIN ERROR AMP
The ML4803 utilizes a one pin voltage error amplifier in
the PFC section (VEAO). The error amplifier is in reality a
current sink which forces 35μA through the output
programming resistor. The nominal voltage at the VEAO
pin is 5V. The VEAO voltage range is 4 to 6V. For a
11.3M resistor chain to the boost output voltage and 5V
steady state at the VEAO, the boost output voltage would
be 400V.
PROGRAMMING RESISTOR VALUE
Equation 1 calculates the required programming resistor
value.
Rp
V
V
I
V
35
V
A
M
BOOST
EAO
PGM
=
=
μ
=
400
50
.
113
.
(1)
PFC VOLTAGE LOOP COMPENSATION
The voltage-loop bandwidth must be set to less than
120Hz to limit the amount of line current harmonic
distortion. A typical crossover frequency is 30Hz.
Equation 1, for simplicity, assumes that the pole capacitor
dominates the error amplifier gain at the loop unity-gain
frequency. Equation 2 places a pole at the crossover
frequency, providing 45 degrees of phase margin.
Equation 3 places a zero one decade prior to the pole.
Bode plots showing the overall gain and phase are shown
in Figures 5 and 6. Figure 4 displays a simplified model of
the voltage loop.
C
Pin
R
V
VEAO
C
f
COMP
p
BOOST
OUT
=
×
×
×
×
×
×
2
2
π
(2)
C
W
220
M
V
V
F
Hz
COMP
=
′
′
′
′
′
′
300
113
400
05
.
2
30
2
.
W
m
p
C
nF
COMP
=
16
LEADING/TRAILING MODULATION
(Continued)
相關PDF資料
PDF描述
ML4824IS-1 Power Factor Correction and PWM Controller Combo
ML4824IS-2 Power Factor Correction and PWM Controller Combo
ML4824CS1 Power Factor Correction and PWM Controller Combo
ML4824CS-2 Power Factor Correction and PWM Controller Combo
ML4824IP-1 Power Factor Correction and PWM Controller Combo
相關代理商/技術參數(shù)
參數(shù)描述
ML4803CP-1 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:8-Pin PFC and PWM Controller Combo
ML4803CP2 功能描述:功率因數(shù)校正 IC PFC Controller PWM Combo RoHS:否 制造商:Fairchild Semiconductor 開關頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
ML4803CP-2 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:8-Pin PFC and PWM Controller Combo
ML4803CS1 功能描述:功率因數(shù)校正 IC PFC Controller PWM Combo RoHS:否 制造商:Fairchild Semiconductor 開關頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
ML4803CS-1 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:8-Pin PFC and PWM Controller Combo
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