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參數(shù)資料
| 型號： | MC33260D |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)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(shù)： | 11/22頁 |
| 文件大小： | 232K |
| 代理商： | MC33260D |
MC33260
http://onsemi.com
11
Pin Numbers are Relevant to the PDIP8 Version
This equation shows that the maximum ontime is inversely
proportional to the squared output voltage. This property is
used for follower boost operation (refer to
Follower Boost
section).
CURRENT SENSE BLOCK
The inductor current is converted into a voltage by
inserting a ground referenced resistor (R
cs
) in series with the
input diodes bridge (and the input filtering capacitor).
Therefore a negative voltage proportional to the inductor
current is built:
Vcs
Rcs
IL
where:
I
L
is the inductor current,
R
cs
is the current sense resistor,
V
cs
is the measured R
cs
voltage.
Figure 27. Current Sensing
V
OCP
60 mV
Zero Current Detection
P
I
R
P
Time
V
OCP
= R
OCP
I
OCP
An overcurrent is detected if V
crosses the threshold (60 mV)
during the Power Switch on state
The negative signal V
cs
is applied to the current sense
through a resistor R
OCP
. The pin is internally protected by a
negative clamp (0.7 V) that prevents substrate injection.
As long as the Pin 4 voltage is lower than (60 mV), the
Current Sense comparator resets the PWM latch to force the
gate drive signal low state. In that condition, the power
MOSFET cannot be on.
During the ontime, the Pin 4 information is used for the
overcurrent limitation while it serves the zero current
detection during the off time.
Zero Current Detection
The Zero Current Detection function guarantees that the
MOSFET cannot turn on as long as the inductor current
hasn’t reached zero (discontinuous mode).
The Pin 4 voltage is simply compared to the (60 mV)
threshold so that as long as V
cs
is lower than this threshold,
the circuit gate drive signal is kept in low state.
Consequently, no power MOSFET turn on is possible until
the inductor current is measured as smaller than (60 mV/R
cs
)
that is, the inductor current nearly equals zero.
Figure 28. Current Sense Block
1
0
I
ocp
(205 A)
Output_Ctrl
LEB
+
60 mV
PWM
Latch
R
R
S
Q
Output_Ctrl
4
To Output Buffer
(Output_Ctrl Low <=> Gate Drive in Low State)
R
OCP
V
OCP
R
cs
D1...D4
Overcurrent Protection
During the power switch conduction (i.e. when the Gate
Drive Pin voltage is high), a current source is applied to the
Pin 4. A voltage drop V
OCP
is then generated across the
resistor R
OCP
that is connected between the sense resistor
and the Current Sense Pin (refer to Figure 28). So, instead of
V
cs
, the sum (V
cs
+ V
OCP
) is compared to (60 mV) and the
maximum permissible current is the solution of the
following equation:
Rcs
Ipkmax
VOCP
60 mV
where:
Ipk
max
is maximum allowed current,
R
cs
is the sensing resistor.
The overcurrent threshold is then:
Ipkmax
ROCP
IOCP
60
103
Rcs
where:
R
OCP
is the resistor connected between the pin and the
sensing resistor (R
cs
),
I
OCP
is the current supplied by the Current Sense Pin
when the gate drive signal is high (power switch
conduction phase). I
OCP
equals 205 A typically.
Practically, the V
OCP
offset is high compared to 60 mV
and the precedent equation can be simplified. The maximum
current is then given by the following equation:
ROCP(k )
Rcs( )
Consequently, the R
OCP
resistor can program the OCP level
whatever the R
cs
value is. This gives a high freedom in the
choice of R
cs
. In particular, the inrush resistor can be utilized.
Ipkmax
0.205 (A)
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| MC33260DG | 功能描述:功率因數(shù)校正 IC Critical Conduction Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33260DR2 | 功能描述:功率因數(shù)校正 IC Critical Conduction RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33260DR2G | 功能描述:功率因數(shù)校正 IC Critical Conduction Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33260P | 功能描述:功率因數(shù)校正 IC Critical Conduction RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33260PG | 功能描述:功率因數(shù)校正 IC Critical Conduction Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
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