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參數資料
| 型號： | MC33260DR2 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩壓器 |
| 英文描述： | GreenLine TM Compact Power Factor Controller: Innovative Circuit for Cost Effective Solutions |
| 中文描述： | 0.5 A POWER FACTOR CONTROLLER, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數： | 14/22頁 |
| 文件大小： | 232K |
| 代理商： | MC33260DR2 |
MC33260
http://onsemi.com
14
Pin Numbers are Relevant to the PDIP8 Version
FOLLOWER BOOST
Traditional PFC preconverters provide the load with a fixed
and regulated voltage that generally equals 230 V or 400 V
according to the mains type (U.S., European, or universal).
In the “Follower Boost” operation, the preconverter
output regulation level is not fixed but varies linearly versus
the ac line amplitude at a given input power.
Figure 32. Follower Boost Characteristics
Traditional Output
V
o
(Follower Boost)
Load
V
ac
This technique aims at reducing the gap between the
output and the input voltages to minimize the boost
efficiency degradation.
Follower Boost Benefits
The boost presents two phases:
The ontime during which the power switch is on. The
inductor current grows up linearly according to a slope
(V
in
/L
p
), where V
in
is the instantaneous input voltage
and L
p
the inductor value.
The offtime during which the power switch is off.
The inductor current decreases linearly according the
slope (V
o
V
in
)/L
p
, where V
o
is the output voltage.
This sequence that terminates when the current equals
zero, has a duration that is inversely proportional to the
gap between the output and input voltages.
Consequently, the offtime duration becomes longer
in follower boost.
Consequently, for a given peak inductor current, the
longer the off time, the smaller power switch duty cycle and
then its conduction dissipation. This is the first benefit of this
technique: the MOSFET ontime losses are reduced.
The increase of the off time duration also results in a
switching frequency diminution (for a given inductor
value). Given that in practise, the boost inductor is selected
big enough to limit the switching frequency down to an
acceptable level, one can immediately see the second benefit
of the follower boost: it allows the use of smaller, lighter and
cheaper inductors compared to traditional systems.
Finally, this technique utilization brings a drastic system
cost reduction by lowering the size and then the cost of both
the inductor and the power switch.
the power switch is on
the power switch is off
IL
time
Ipk
Vout
traditional preconverter
follower boost preconverter
Vin
Vin
Vin
Vin
IL
IL
Figure 33. OffTime Duration Increase
Follower Boost Implementation
In the MC33260, the ontime is differently controlled
according to the feedback current level. Two areas can be
defined:
When the feedback current is higher than I
regL
(refer
to regulation section), the regulation block output
(V
control
) is modulated to force the output voltage to a
desired value.
On the other hand, when the feedback current is lower
than I
regL
, the regulation block output and therefore,
the ontime are maximum. As explained in
PWM
Latch Section,
the ontime is then inversely
proportional to the output voltage square. The
Follower Boost is active in these conditions in which
the ontime is simply limited by the output voltage
level. Note: In this equation, the Feedback Pin voltage
(V
pin1
) is neglected compared to the output voltage
(refer to the
PWM Latch Section).
ton
tonmax
Cpin3
Kosc
R2
o
V2
o
where:
C
pin3
is the total oscillator capacitor (sum of the
internal and external capacitors C
int
+ C
T
),
K
osc
is the ratio (oscillator swing over oscillator gain),
V
o
is the output voltage,
R
o
is the feedback resistor.
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相關代理商/技術參數 |
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|---|---|
| MC33260DR2G | 功能描述:功率因數校正 IC Critical Conduction Mode PFC 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 |
| MC33260P | 功能描述:功率因數校正 IC Critical Conduction 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 |
| MC33260PG | 功能描述:功率因數校正 IC Critical Conduction Mode PFC 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 |
| MC33261 | 制造商:SPC Multicomp 功能描述:HEATSINK TO220/218 16.7/W 制造商:SPC Multicomp 功能描述:HEATSINK TO220/218 16.7C/W 制造商:SPC Multicomp 功能描述:HEAT SINK; Packages Cooled:TO-218 / TO-220; Thermal Resistance:16.7C/W; External Height - Imperial:1"; External Height - Metric:25.4mm; External Width - Imperial:0.654"; External Width - Metric:16.6mm; Heat Sink Material:Aluminium ;RoHS Compliant: Yes |
| MC33261P | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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