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參數資料
| 型號： | MC78T08ABT |
| 廠商： | Motorola, Inc. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| 中文描述： | 三端固定電壓調節器 |
| 文件頁數： | 9/12頁 |
| 文件大小： | 162K |
| 代理商： | MC78T08ABT |
MC78T00 Series
APPLICATIONS INFORMATION
9
MOTOROLA ANALOG IC DEVICE DATA
Design Considerations
The MC78T00 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 regulator’s
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.
Figure 14. Current Regulator
Figure 15. Adjustable Output Regulator
Figure 16. Current Boost Regulator
Figure 17. Current Boost With
Short Circuit Protection
5.0 V
R
Input
0.33
μ
F
MC78T05
R
IO
The MC78T05 regulator can also be used as a current source when
connected as above. In order to minimize dissipation the MC78T05 is
chosen in this application. Resistor R determines the current
as follows:
IO =
+ IB
IB
IB
0.7 mA over line, load and Temperature changes
3.5 mA
For example, a 2.0 A current source would require R to be a 2.5
,
10 W resistor and the output voltage compliance would be the input
voltage less 7.0 V.
Constant
Current to
Grounded Load
Input
Output
1.0k
4
6
7
2
3
–
+
0.1
μ
F
10k
MC1741
VO, 8.0 V to 20 V
Vin – VO
≥
2.5 V
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 3.0 V greater
than the regulator voltage.
0.33
μ
F
R
0.1
μ
F
Output
1.0
μ
F
The MC78T00 series can be current boosted with a PNP transistor. The
2N4398 provides current to 15 A. Resistor R in conjuction 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 the VBE of the pass transistor.
2N4398 or Equiv
MC78TXX
MC78TXX
Input
Rsc
2N4398
or Equiv.
Output
R
MJ2955
or Equiv.
1.0
μ
F
The circuit of Figure 17 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, an eight–ampere power transistor is specified.
MC78T05
XX = 2 digits of type number indicating voltage.
XX = 2 digits of type number indicating voltage.
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| MC78T05 | 5.0 AMP POSITIVE VOLTAGE REGULATOR |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MC78T08CT | 制造商:ON Semiconductor 功能描述:IC, LDO VOLT REG, 8V, 3A, TO-220, Primary Input Voltage:23V, Output Voltage Fixe |
| MC78T12ACT | 功能描述:IC REG LDO 12V 3A TO220AB RoHS:否 類別:集成電路 (IC) >> PMIC - 穩壓器 - 線性 系列:- 產品變化通告:Heatsink Pkg Change 09/Oct/2007 標準包裝:50 系列:- 穩壓器拓撲結構:正，固定式 輸出電壓:24V 輸入電壓:最高 40 V 電壓 - 壓降（標準）:2V @ 1A 穩壓器數量:1 電流 - 輸出:1A 電流 - 限制（最小）:- 工作溫度:0°C ~ 125°C 安裝類型:通孔 封裝/外殼:TO-220-3 供應商設備封裝:TO-220-3 包裝:管件 |
| MC78T12BT | 制造商:ON Semiconductor 功能描述:IC, LDO VOLT REG, 12V, 3A, TO-220, Primary Input Voltage:22V, Output Voltage Fix |
| MC78T12CK | 制造商:MOTOROLA 功能描述:TO-3 VOLTAGE REGULATOR |
| MC78T12CT | 功能描述:線性穩壓器 - 標準 Positive Voltage Reg 3Terminal 3a 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: 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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