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參數(shù)資料
| 型號： | KA7541 |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Simple Ballast Controller |
| 中文描述： | 0.3 A FLUORESCENT LIGHT CONTROLLER, 56 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | DIP-8 |
| 文件頁數(shù)： | 5/14頁 |
| 文件大小： | 95K |
| 代理商： | KA7541 |
KA7541
5
Start-up Circuit
Start up current is supplied to the IC through the start up resistor (Rst). In order to reduce the power dissipation in Rst, the Rst
is connected to the full wave rectified output voltage.
The following equation can be used to calculate the size of Rst
The size of start up capacitor (Cst) is normally decided in terms of the start up time and operating current build up time with
auxiliary operating current source.
The turn off snubber capacitor (Cq2) and two diodes (D1, D2) constitute the auxiliary operating current source for the IC. The
charging current through the Cq2 flows into the IC and also charges the start-up capacitor. If the size of Cq2 is increased, the
V
CC
voltage of the Cst is also increased.
Figure 1. Start up circuit
Oscillator
The gate drive output frequency is as half as that of the triangular waveform in timing capacitor (Ct) at pin #2. In normal
operating mode, the timing capacitor charging current is 50
μ
A. The discharging current is seven times of the charging current
(7
×
50
μ
A). The charging period of the timing capacitor is the on duty of the gate drive. The discharging period is the off duty
of the gate drive.
The rising slope and falling slope of the triangular waveform are as following.
Rising slope: dv / dt = i / C = 50
μ
A / Ct
Falling slope: dv / dt = i / C = 7
×
50
μ
A / Ct
For example, when the timing capacitor is 180pF,
Tch = 6.69
μ
Tdis = 0.956
μ
Rst
-----------------------------------–
Ist max
,
<
----------------------–
×
10
0.25
3
–
440k
=
=
P
RSt
---------------------------------------------------–
(
)
2
R
St
0.5W
≤
=
R
St
2
Vin ac_max
)
2
Vcc
–
(
)
2
×
≥
R
St
260K
≥
260K
R
St
440K
≤
≤
∴
Q1
Q2
Cq2
D1
D2
Rectifier
Output
Rst
Cst
+
To V
CC
(Pin 8)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| KA7541D | Simple Ballast Controller |
| KA75420Z | Voltage Detector |
| KA75290M | Voltage Detector |
| KA75290Z | Voltage Detector |
| KA75310M | Voltage Detector |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| KA7541D | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Ballast Controller Electronic RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| KA7541DTF | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Ballast Controller Electronic RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| KA75420 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Voltage Detector |
| KA75420M | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Voltage Detector |
| KA75420MTF | 功能描述:監(jiān)控電路 Voltage Detector 4.2V RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
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