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參數(shù)資料
| 型號： | ML4827CS-2 |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Fault-Protected PFC and PWM Controller Combo |
| 中文描述： | 0.5 A POWER FACTOR CONTROLLER WITH POST REGULATOR, PDSO16 |
| 封裝： | PLASTIC, SOIC-16 |
| 文件頁數(shù)： | 13/16頁 |
| 文件大小： | 256K |
| 代理商： | ML4827CS-2 |
ML4827
13
The ML4827 should be locally bypassed with a 10nF and
a 1
μ
F ceramic capacitor. In most applications, an
electrolytic capacitor of between 100
μ
F and 330
μ
F is also
required across the part, both for filtering and as part of
the start-up bootstrap circuitry.
LEADING/TRAILING MODULATION
Conventional Pulse Width Modulation (PWM) techniques
employ trailing edge modulation in which the switch will
turn on right after the trailing edge of the system clock.
The error amplifier output voltage is then compared with
the modulating ramp. When the modulating ramp reaches
the level of the error amplifier output voltage, the switch
will be turned OFF. When the switch is ON, the inductor
current will ramp up. The effective duty cycle of the
trailing edge modulation is determined during the ON
time of the switch. Figure 5 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 6
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
Figure 6. Typical Leading Edge Control Scheme.
Figure 5. Typical Trailing Edge Control Scheme.
RAMP
VEAO
TIME
VSW1
TIME
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
U2
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
FUNCTIONAL DESCRIPTION
(Continued)
相關PDF資料 |
PDF描述 |
|---|---|
| ML4827CS-1 | Fault-Protected PFC and PWM Controller Combo |
| ML4827 | Fault-Protected PFC and PWM Controller Combo |
| ML4851CS-3 | Low Current, Voltage Boost Regulator |
| ML4861CS-3 | Low Voltage Boost Regulator |
| ML4861ES-6 | Low Voltage Boost Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ML4827IP1 | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML4827IP-1 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Fault-Protected PFC and PWM Controller Combo |
| ML4827IP-2 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Fault-Protected PFC and PWM Controller Combo |
| ML4827IS-1 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Fault-Protected PFC and PWM Controller Combo |
| ML4827IS-2 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Fault-Protected PFC and PWM Controller Combo |
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