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參數(shù)資料
| 型號： | KA7540D |
| 廠商： | SAMSUNG SEMICONDUCTOR CO. LTD. |
| 英文描述： | Simple Dimming Ballast Control IC |
| 中文描述： | 簡單的調(diào)光鎮(zhèn)流器控制IC |
| 文件頁數(shù)： | 6/14頁 |
| 文件大小： | 104K |
| 代理商： | KA7540D |
KA7540
6
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 AC line voltage.
The following equation can be used to calculate the value of Rst.
The value of start-up capacitor (Cst) is normally determined in terms of the start-up time and operating current build up time
with the 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 value of Cq2 is increased, the
V
CC
voltage of the Cst is also increased.
Figure 1. Start-up circuit
Oscillator
The frequency of the gate drive output 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). During the charging period, one of the two MOSFETs remains ON state. On the contrary both of MOSFETs are
OFF during the discharging period.
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 470pF,
V(Vhigh - Vlow) = (2.86V - 1.0V) = 1.86V,
Tch = 17.5
μ
s,
Tdis = 2.5
μ
s
Rst
-----------------------------------–
≤
----------------------–
–
0.3
103
×
356K
=
=
PRst
Vin ac_max
---------------------------------------------------------------------------
)
2
–
(
)
2
Rst
1W
≤
=
Rst
Vin ac_max
)
2
VCC
–
(
)
2
≥
Rst
130K
≥
130K
Rst
356K
≤
≤
∴
Q1
Q2
Cq2
D1
D2
Rectifier
Output
Rst
Cst
+
To V
CC
(Pin 8)
相關PDF資料 |
PDF描述 |
|---|---|
| KA7541 | Simple Ballast Controller |
| KA7541D | Simple Ballast Controller |
| KA75420Z | Voltage Detector |
| KA75290M | Voltage Detector |
| KA75290Z | Voltage Detector |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| KA7540DTF | 功能描述:開關變換器、穩(wěn)壓器與控制器 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 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| KA7541 | 功能描述:開關變換器、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 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| KA7541D | 功能描述:開關變換器、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 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| KA7541DTF | 功能描述:開關變換器、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 開關頻率:1 MHz 工作溫度范圍: 安裝風格: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 |
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