LM7908CT

LM7908CT Application Field and Working Principle

The LM7908CT is a negative voltage regulator that can be used in a variety of applications. It is a three-terminal adjustable device that provides a constant output voltage for a given input voltage. The main features of the LM7908CT include: an adjustable output voltage from -12.6V to -30.0V, adjustable current limit from 0 to 1A and thermal protection. The LM7908CT can also provide power to both digital and analog circuits without the need for an additional power supply.

The application field of the LM7908CT can include power supplies for portable equipment, automotive applications, and battery-backed systems. This voltage regulator can also be used in embedded systems, digital signal processing (DSP) applications, and computer and communications equipment. Furthermore, the LM7908CT can also be used in telecommunication systems and high reliability systems.

Functional Block Diagram

The LM7908CT consists of an adjustable voltage regulator and a negative voltage reference. It also includes an adjustable current limit and thermal protection. The adjustable voltage regulator receives an input voltage from the system supply and a reference voltage from the voltage reference. This reference voltage is compared to the input voltage. If the input voltage is higher than the reference voltage, the transistor will turn on to reduce the size of the voltage difference between the two voltages. This will create a constant output voltage.

Working Principle

The LM7908CT is used as a negative voltage regulator. It has three terminals, the input voltage (Vin), the output voltage (Vout), and the adjust pin (Vadj.). When the Vin is higher than Vadj., the output voltage (Vout) is created and the output voltage is the same as the input voltage (Vin). The voltage regulator works by controlling the output voltage with a series of resistors and capacitors.

The adjust pin (Vadj.) is used to adjust the output voltage. When Vadj. is increased, the output voltage (Vout) is increased too. This can be done by increasing or decreasing the resistance on the adjust pin.

The current limiting is provided by the current limit pin (Vlmt.). When the current limit pin (Vlmt.) increases, the current limit is increased too. This can be done by increasing or decreasing the resistance on the current limit pin.

Finally, the thermal protection is provided by the thermal sensing diode. This diode is connected to the adjust pin (Vadj.) and if the voltage drops below the thermal shutdown voltage, the regulator will shut down to prevent damage.

Conclusion

The LM7908CT is a negative voltage regulator that can provide a wide range of output voltages from -12.6V to -30.0V. It also has adjustable current limit and thermal protection. This voltage regulator can be used in power supplies, automotive applications, embedded systems, digital signal processing applications, computer and communications equipment and telecommunication systems.

This regulator can help simplify the design process by ensuring a stable output voltage over a range of input voltages. This makes it an ideal choice for applications that require precise, reliable, and consistent power management.