You can also check on 78 series for positive voltage regulators. When you are designing an analog circuit, the circuit might need negative voltage either as a power source or as a reference voltage. In both cases will be an ideal choice when you need a negative 12V. The output current of this IC is upto 1A, however with appropriate heat sink the datasheet says that a peak current of 2.

Author:Mezitilar Kajicage
Country:Sao Tome and Principe
Language:English (Spanish)
Published (Last):17 September 2013
PDF File Size:9.22 Mb
ePub File Size:15.14 Mb
Price:Free* [*Free Regsitration Required]

The ground pin is connected to the ground of the circuit. The range of input signal is 5V to 24V. Safe area protection is provided for output transistors.

It has a high power supply rejection ratio and low noise. The output current is 1. It has a low quiescent current which ensures good regulation.

Where to use it? LM IC is used in designing analog circuits which require negative voltages. You can use this IC to get volts. Microcontrollers need a smooth and regulated voltage at the input to function smoothly. Therefore, LM IC is used for generating smooth voltage. It is also useful in designing split power supplies and sensors. Moreover, it is suitable for use in fixed voltage applications. A basic circuit of this IC is mentioned below.

It requires only two capacitors in performing a stable operation. One capacitor is connected at the input and the other at the output. They are used to filter noise. To avoid excessive power dissipation, they have a thermal overload protection system incorporated inside the IC. Short circuit protection is provided to keep the current in limits otherwise it can damage the IC.

Pin 2 is supplied with a negative input signal in a range of — 5V to — 24V. LM consists of a pass transistor. The output current decreases when the voltage across this transistor increases. Therefore, safe area compensation is provided in order to compensate for the losses.

The life of this device can be increased using heat sink which increases its power dissipation capability. Negative voltage regulator using LM In this circuit, we apply a 14 volts dc at the input of Capacitors C1 and C2 are filter capacitors.

These capacitors avoid voltage fluctuations at the input and output terminals. Greater the capacitor values less will be voltage fluctuations. But we always use optimum and easily available capacitor values. We connect a voltmeter at the output to measure output voltage.

As you can see from the circuit diagram that output is negative 12 volts. The positive voltage regulator LM and negative voltage regulator LM is used in this project. The circuit diagram is given below.


LM7905 Fairchild Semiconductor, LM7905 Datasheet



LM7912 Negative 12 Volts Voltage Regulator




Related Articles