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參數(shù)資料
| 型號(hào)： | 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)： | 15/24頁 |
| 文件大?。?/td> | 405K |
| 代理商： | MC44603AP |
MC44603A
15
MOTOROLA ANALOG IC DEVICE DATA
So, as fS = 1 /(Tcharge + Tdischarge) when the Regul
arrangement is not activated, the operating frequency can be
obtained from the graph in Figure 1.
NOTE:
The output is disabled by the signal VOSC prot when
VCT is lower than 1.0 V (refer to Figure 30).
Synchronization and Demagnetization Blocks
To enable the output, the LOSC latch complementary
output must be low. Reset is activated by the Ldisch output
during the discharge phase. To restart, the LOSC has to be set
(refer to Figure 34). To perform this, the demagnetization
signal and the synchronization must be low.
Synchronization:
The synchronization block consists of two comparators
that compare the synchronization signal (external) to 0.7 and
3.7 V (typical values). The comparators’ outputs are
connected to the input of an AND gate so that the final output
of the block should be :
– high when 0.7 < SYNC < 3.7 V
– low in the other cases.
As a low level is necessary to enable the output,
synchronized low level pulses have to be generated on the
output of the synchronization block. If synchronization is not
required, the Pin 9 must be connected to the ground.
Figure 36. Synchronization
Oscillator
Output Buffer
3.7 V
0.7 V
9
Sync
Demagnetization:
In flyback applications, a good means to detect magnetic
saturation of the transformer core, or demagnetization,
consists in using the auxiliary winding voltage. This voltage is:
– negative during the on–time,
– positive during the off–time,
– equal to zero for the dead–time with generally some
–
ringing (refer to Figure 37).
That is why, the MC44603A demagnetization detection
consists of a comparator that can compare the auxiliary
winding voltage to a reference that is typically equal to
65 mV.
Figure 37. Demagnetization Detection
VPin 8
0.75 V
65 mV
–0.33 V
Zero Current
Detection
On–Time
Off–Time
Dead–Time
A diode D has been incorporated to clamp the positive
applied voltages while an active clamping system limits the
negative voltages to typically –0.33 V. This negative clamp
level is sufficient to avoid the substrate diode switching on.
In addition to the comparator, a latch system has been
incorporated in order to keep the demagnetization block
output level low as soon as a voltage lower than 65 mV is
detected and as long as a new restart is produced (high level
on the output) (refer to Figure 38). This process prevents
ringing on the signal at Pin 8 from disrupting the
demagnetization detection. This results in a very accurate
demagnetization detection.
The demagnetization block output is also directly
connected to the output, disabling it during the
demagnetization phase (refer to Figure 33).
NOTE:
The demagnetization detection can be inhibited by
connecting Pin 8 to the ground.
Figure 38. Demagnetization Block
C Dem
Oscillator
Output
Buffer
R
Demag
S
Q
VCC
Negative Active
Clamping System
8
D
65 mV
VDemag Out
Standby
Power Losses in a Classical Flyback Structure
Figure 39. Power Losses in a Classical
Flyback Structure
Vin
RICL
AC Line
+
Rstartup
VCC
Clamping
Network
Snubber
MC44603A
RS
+
In a classical flyback (as depicted in Figure 39), the
standby losses mainly consist of the energy waste due to:
– the startup resistor Rstartup
– the consumption of the IC and
–
the power switch control
– the inrush current limitation resistor RICL
– the switching losses in the power switch
– the snubber and clamping network
Pstartup is nearly constant and is equal to:
(Vin–VCC)2Rstartup
Pstartup
Pcontrol
PICL
PSW
PSN–CLN
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(fēng)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(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(fēng)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(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(fēng)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(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(fēng)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(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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