Microcircuit TL431 datasheet: description, purpose, technical characteristics

The TL431 datasheet chip was created in the late 1970s, but to this day it is widely used in radio amateurs and industry. This chip is an integral adjustable regulator, which has found wide application in various power supplies.

Description of work

TL431 datasheet has only three outputs, but in its case ten transistors (comparator) are hidden. The functions of this device and the 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 characteristic. The main feature of such a device is the ability with an external divider to change the stabilization voltage within the limits of 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 consists of the following components:

• Built-in (very stable) source of 2.5 V reference voltage, which is connected to the comparator's inverted input;
• One input of a direct level;
• At the output of the comparator, a transistor, whose emitter and collector are combined with power contacts;
• Diode for protection against reverse polarity.

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 (correspondingly, the transistor on the output of the microchip opens), it is necessary O on its input to apply voltage above the reference one. At the input of the chip included voltage divider, consisting of two resistors, it divides the voltage in half. This means that the comparator will open when the input to the input of the circuit is 5 V, 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 in the range of 2.5-36 V.

Purpose and scope of application

There is no computer power supply that does not have a TL431 datasheet chip. Also it can be found in almost all impulse low-power power supplies, for example, in charging for mobile phones. These chips can be used not only for their intended purpose (zener diode for power supplies), but also to create on their base various light indicators and audible alarms. With the help of such devices, many different parameters are monitored (but the main one is still the voltage). There are many schemes based on the TL431 datasheet, thanks to which it is possible to assemble devices that control the level of liquid in the tank, humidity and temperature, gas or liquid pressure, illumination. The listed options are not the only possible ones, the application of this chip is in fact very wide, it all depends on the designer's desire.

Very often novice radio amateurs are interested in what can replace the TL431. The analogue, of course, exists. So, it is possible to use imported products КА431 and domestic devices КР142ЕН19А, К1156ЕР5х.

Let's sum up the results

The integrated microcircuit of the company "TEXAS INSTRUMENTS" is very reliable, has a wide operating range, is easy to operate, and most importantly, has an affordable price. Due to its characteristics, it is produced more than forty years and still remains in demand.