The TL431 datasheet was created in the late 70s, but to this day it is widely used in amateur radio and industrial applications. This microcircuit is an integral adjustable stabilizer that has been widely used in various power supplies.
Work description
The TL431 datasheet has only three outputs, but ten transistors (a comparator) are hidden in its case. The functions of this device and a conventional stabilizer are similar. However, due to this complication, the chip has a higher level of thermal stability, as well as an increased slope of the characteristics. The main feature of such a device is the ability to use an external divider to change the stabilization voltage within 2.5-30 V. For some models, the lower threshold may be 1.25 V. The circuit of the comparator integrated into the datasheet TL431 product consists of the following components:
- built-in source (very stable) of the reference voltage of 2.5 V, which is connected to the inverse input of the comparator;
- one direct level input;
- at the output of the comparator, a transistor whose emitter and collector are combined with power contacts;
- diode for reverse polarity protection.
The transistor has a maximum load current of 100 mA, and a maximum voltage of 36 V. In order for the built-in comparator to work (accordingly, the transistor opens at the output of the microcircuit), it is necessary
o at its input, apply
voltage above the reference. At the input of the microcircuit,
a voltage divider is included
, consisting of two resistors, it divides the voltage value in half. This means that the comparator will open when it receives 5 V at the input of the circuit, but at the output of the divider we get 2.5 V. If you increase the resistance of the resistor, you must also increase the supply voltage. It turns out that this chip can work as a zener diode within 2.5-36 V.
Purpose and scope
There is not a single computer power supply unit that does not have a TL431 datasheet chip. It can also be found in almost all pulsed low-power sources, for example, in chargers for mobile phones. These microcircuits can be used not only for their intended purpose (zener diode for power supplies), but also create various light indicators and sound alarms on their basis. With the help of such devices, many different parameters are monitored (but the main one is still voltage). There are many schemes based on the TL431 datasheet, thanks to which it is possible to assemble devices that monitor the level of liquid in the tank, humidity and temperature, gas or liquid pressure, and light. The listed options are not the only possible ones, the use of this chip is actually quite wide, it all depends on the desire of the designer.
Very often, beginner hams are interested in how to replace TL431. An analogue, of course, exists. So, you can use imported products KA431 and domestic devices KR142EN19A, K1156ER5x.
To summarize
The integrated circuit of the TEXAS INSTRUMENTS company is very reliable, has a wide operating range, is easy to operate, and most importantly, has an affordable price. Due to its characteristics, it has been produced for more than forty years and still remains in demand.