L7805 datasheet(23/34 Pages) STMICROELECTRONICS

tên linh kiện	L7805

Giải thích chi tiết về linh kiện	POSITIVE VOLTAGE REGULATORS

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L7800 SERIES

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Figure 35: Adjustable Output Voltage with Temperature Compensation

NOTE: Q2 is connected as a diode in order to compensate the variation of the Q1 VBE with the temperature. C allows a slow rise time of the VO.

Figure 36: Light Controllers (VOmin = VXX + VBE)

Figure 37: Protection against Input Short-Circuit with High Capacitance Loads

Application with high capacitance loads and an output voltage greater than 6 volts need an external diode (see fig. 33) to protect the device

against input short circuit. In this case the input voltage falls rapidly while the output voltage decrease slowly. The capacitance discharges by

means of the Base-Emitter junction of the series pass transistor in the regulator. If the energy is sufficiently high, the transistor may be de-

stroyed. The external diode by-passes the current from the IC to ground.

VO = VXX (1+ ) + VBE

VO rises when the light goes up

VO falls when the light goes up

L7805 bảng dữ liệu(PDF) 23 Page - STMicroelectronics