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參數(shù)資料
| 型號： | MC7808CDT |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | 2.25 A, 4.5-V to 18-V Input Wide Adjust Miniature Power Module 5-DIP MODULE -40 to 85 |
| 中文描述： | 8 V FIXED POSITIVE REGULATOR, PSSO2 |
| 封裝： | DPAK-3 |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 278K |
| 代理商： | MC7808CDT |
MC7800, MC7800A, LM340, LM340A Series
APPLICATIONS INFORMATION
14
MOTOROLA ANALOG IC DEVICE DATA
Design Considerations
The MC7800 Series of fixed voltage regulators are
designed with Thermal Overload Protection that shuts down
the circuit when subjected to an excessive power overload
condition, Internal Short Circuit Protection that limits the
maximum current the circuit will pass, and Output Transistor
Safe–Area Compensation that reduces the output short
circuit current as the voltage across the pass transistor is
increased.
In many low current applications, compensation
capacitors are not required. However, it is recommended
that the regulator input be bypassed with a capacitor if the
regulator is connected to the power supply filter with long
wire lengths, or if the output load capacitance is large. An
input bypass capacitor should be selected to provide good
high–frequency characteristics to insure stable operation
under all load conditions. A 0.33
μ
F or larger tantalum,
mylar, or other capacitor having low internal impedance at
high frequencies should be chosen. The bypass capacitor
should be mounted with the shortest possible leads directly
across the regulators input terminals. Normally good
construction techniques should be used to minimize ground
loops and lead resistance drops since the regulator has no
external sense lead.
IO
5.0 V
R
IB
Figure 7. Current Regulator
Figure 8. Adjustable Output Regulator
Figure 9. Current Boost Regulator
Figure 10. Short Circuit Protection
The MC7800 regulators can also be used as a current source when
connected as above. In order to minimize dissipation the MC7805C is
chosen in this application. Resistor R determines the current as follows:
For example, a 1.0 A current source would require R to be a 5.0
,
10 W resistor and the output voltage compliance would be the input
voltage less 7.0 V.
IB
3.2 mA over line and load changes.
Input
0.33
μ
F
R
IO
MC7805
Constant
Current to
Grounded
Load
The addition of an operational amplifier allows adjustment to higher or
intermediate values while retaining regulation characteristics. The
minimum voltage obtainable with this arrangement is 2.0 V greater than the
regulator voltage.
Input
MC7805
Output
0.33
μ
F
10 k
MC1741G
7
6
4
1.0 k
VO = 7.0 V to 20 V
VIN = VO
≥
2.0 V
0.1
μ
F
3
2
The MC7800 series can be current boosted with a PNP transistor. The
MJ2955 provides current to 5.0 A. Resistor R in conjunction with the VBE
of the PNP determines when the pass transistor begins conducting; this
circuit is not short circuit proof. Input/output differential voltage minimum is
increased by VBE of the pass transistor.
XX = 2 digits of type number indicating voltage.
MC78XX
Input
Output
R
1.0
μ
F
MJ2955 or Equiv.
1.0
μ
F
The circuit of Figure 9 can be modified to provide supply protection against
short circuits by adding a short circuit sense resistor, RSC, and an
additional PNP transistor. The current sensing PNP must be able to handle
the short circuit current of the three–terminal regulator. Therefore, a
four–ampere plastic power transistor is specified.
XX = 2 digits of type number indicating voltage.
1.0
μ
F
MC78XX
MJ2955
or Equiv.
Output
RSC
R
2N6049
or Equiv.
≥
10
μ
F
RSource
0.33
μ
F
Input
RSource
0.33
μ
F
≥
10
μ
F
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MC7808CDTG | 功能描述:線性穩(wěn)壓器 - 標準 8V 1A Postive RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調節(jié): 最大輸入電壓:5.5 V 線路調整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MC7808CDTRK | 功能描述:線性穩(wěn)壓器 - 標準 8V 1A Postive RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調節(jié): 最大輸入電壓:5.5 V 線路調整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MC7808CDTRKG | 功能描述:線性穩(wěn)壓器 - 標準 8V 1A Postive RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調節(jié): 最大輸入電壓:5.5 V 線路調整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MC7808CDTT5 | 功能描述:IC REG LDO 8V 1A DPAK RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標準包裝:3,000 系列:- 穩(wěn)壓器拓撲結構:正，固定式和可調式 輸出電壓:3.3V，1.25 V ~ 5.7 V 輸入電壓:4.5 V ~ 7 V 電壓 - 壓降（標準）:1.1V @ 1A 穩(wěn)壓器數(shù)量:2 電流 - 輸出:1A 電流 - 限制（最?。?1A 工作溫度:0°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:TO-252-5，DPak（4 引線 + 接片），TO-252AD 供應商設備封裝:PPAK 包裝:管件 其它名稱:497-3576-5 |
| MC7808CDTT5G | 功能描述:線性穩(wěn)壓器 - 標準 ANA 1A 8V VREG RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調節(jié): 最大輸入電壓:5.5 V 線路調整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
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