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參數(shù)資料
| 型號： | MC44603AP |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| 中文描述： | 0.75 A SWITCHING CONTROLLER, 250 kHz SWITCHING FREQ-MAX, PDIP16 |
| 封裝： | PLASTIC, DIP-16 |
| 文件頁數(shù)： | 16/24頁 |
| 文件大?。?/td> | 405K |
| 代理商： | MC44603AP |
MC44603A
16
MOTOROLA ANALOG IC DEVICE DATA
PICL only depends on the current drawn from the mains.
Losses can be considered constant. This waste of energy
decreases when the standby losses are reduced.
Pcontrol increases when the oscillator frequency is
increased (each switching requires some energy to turn on
the power switch).
PSW and PSN–CLN are proportional to the switching
frequency.
Consequently, standby losses can be minimized by
decreasing the switching frequency as much as possible.
The MC44603A was designed to operate at a standby
frequency lower than the normal working one.
Standby Power Calculations with MC44603A
During a switching period, the energy drawn by the
transformer during the on–time to be transferred to the output
during the off–time, is equal to:
1
where:
E
– L is the transformer primary inductor,
– lpk is the inductor peak current.
Input power is labelled Pin:
Pin
0.5 x L x Ipk2x fS
where fS is the normal working switching frequency.
Also,
Ipk
VCS
RS
where RS is the resistor used to measure the power switch
current.
Thus, the input power is proportional to VCS2
(
VCS being
the internal current sense comparator input).
That is why the standby detection is performed by creating
a VCS threshold. An internal current source (0.4 x Iref) sets
the threshold level by connecting a resistor to Pin 12.
As depicted in Figure 40, the standby comparator
noninverting input voltage is typically equal to (3.0 x VCS + VF)
while the inverter input value is (VR P Stby + VF).
Figure 40. Standby
CStby
Current Mirror X2
RP Stby
12
ERAmpOut
0.4 Iref
0.6 Iref
0
1
2R
1R
C. S. Comparator
0.8 Iref
0.25
IF Stby
VrefVref
VrefVref
Vref
0.2 Iref
Oscillator
Discharge
Current
1
0
IDischarge/2
IDischarge
13
The VCS threshold level is typically equal to
[(VR P Stby)/3] and if the corresponding power threshold is
labelled PthL:
VR P Stby
PthL
0.5 x L x
3.0 RS
2x fS
And as:
VR P Stby
RP Stbyx 0.4 x Iref
RR P Stbyx 0.4 xRref
RP Stby
10.6 x RSx Rref
Vref
x
PthL
L x fS
Thus, when the power drawn by the converter decreases,
VCS decreases and when VCS becomes lower than [VCS–th
x (VR P Stby)/3], the standby mode is activated. This results in
an oscillator discharge current reduction in order to increase
the oscillator period and to diminish the switching frequency.
As it is represented in Figure 40, the (0.8 x Iref) current
source is disconnected and is replaced by a lower value one
(0.25 x IF Stby).
Where: IF Stby = Vref/RF Stby
In order to prevent undesired mode switching when power
is close to the threshold value, a hysteresis that is
proportional to VR P Stby is incorporated creating a second
VCS threshold level that is equal to [2.5 x (VR P Stby)/3]. When
the standby comparator output is high, a second current
source (0.6 x Iref) is connected to Pin 12.
Finally, the standby mode function can be shown
graphically in Figure 41.
Figure 41. Dynamic Mode Change
PthL
PthH
Pin
[(VR P Stby)/3]
2.5 x [(VR P Stby)/3]
1
VCS
fStby
fS
Normal
Working
Standby
This curve shows that there are two power threshold
levels:
– the low one:
PthL fixed by VR P Stby
PthH
(2.5)2x PthLx
fStby
fS
fStby
fS
– the high one:
PthH
6.25 x PthLx
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相關代理商/技術參數(shù) |
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|---|---|
| MC44603APG | 功能描述:電流型 PWM 控制器 Voltage/Current PWM w/Bust Mode Standby RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44603DW | 功能描述:電流型 PWM 控制器 Voltage/Current PWM RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44603DWR2 | 功能描述:電流型 PWM 控制器 Voltage/Current PWM RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44603DWR2G | 功能描述:電流型 PWM 控制器 Voltage/Current PWM w/Bust Mode Standby RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44603P | 功能描述:電流型 PWM 控制器 Voltage/Current PWM RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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