参数资料
型号: MC7808BDTRK
厂商: ON SEMICONDUCTOR
元件分类: 固定正电压单路输出标准稳压器
英文描述: THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS
中文描述: 8 V FIXED POSITIVE REGULATOR, PSSO2
封装: DPAK-3
文件页数: 14/33页
文件大小: 289K
代理商: MC7808BDTRK
MC7800, MC7800A, MC7800AE, NCV7800
http://onsemi.com
21
APPLICATIONS INFORMATION
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
SafeArea 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
highfrequency characteristics to insure stable operation
under all load conditions. A 0.33
mF 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.
I
O +
5.0V
R
) I
B
Figure 9. Current Regulator
Figure 10. Adjustable Output Regulator
Figure 11. Current Boost Regulator
Figure 12. 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
W,
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
mF
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
mF
10 k
MC1741G
7
6
4
1.0 k
VO = 7.0 V to 20 V
VIN = VO ≥ 2.0 V
0.1
mF
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
mF
MJ2955 or Equiv.
1.0
mF
The circuit of Figure 11 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
mF
MC78XX
MJ2955
or Equiv.
Output
RSC
R
2N6049
or Equiv.
≥ 10
mF
RSource
0.33
mF
Input
RSource
0.33
mF
≥ 10
mF
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相关代理商/技术参数
参数描述
MC7808BDTRKG 功能描述:线性稳压器 - 标准 8V 1A Postive RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L
MC7808BDTRKG 制造商:ON Semiconductor 功能描述:Linear Voltage Regulator IC
MC7808BT 功能描述:线性稳压器 - 标准 8V 1A Postive RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L
MC7808BTG 功能描述:线性稳压器 - 标准 8V 1A Postive RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L
MC7808C 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:THREE TERMINAL POSITIVE FIXED VOLTAGE REGULATORS