LP3990 – A Positive Voltage Regulator : Working & Its Applications

• The voltage regulator device gives a regulated output to a device for proper working.
• So, other device gets damaged if we give a fluctuating voltage at the input.
• A voltage regulator is used for this type of circuit and the feedback differential amplifier is used to regulate the output.
• LP3990 is a positive voltage regulator device that is a low noise, low quiescent current positive voltage regulator.
• This device is specially designed for digital applications and it’s stable with a spacing-saving small ceramic capacitor of 1microfarad.

Working/Block Diagram

Enable (EN):

• This Enable (EN) pin is internally held low by a 1-MΩ resistor to GND.
• If the device is fully enabled under all operating conditions then Enable pin voltage must be higher than the VIH threshold.
• If the device is fully disabled then EN pin voltage must be lower than the VIL threshold.
• If the EN pin is left open will then the LP3990 output be disabled.

Thermal Overload Protection (TSD):

• It disables the output when the junction temperature increases to approximately 155°C which allows the device to cool.
• The output circuitry enables then the junction temperature to cool to approximately 140°C.
• The thermal protection circuit is operated based on the value of power dissipation, thermal resistance, and ambient temperature.
• The circuitry of the LP3990 has been designed to protect against temporary thermal overload conditions.

Pin Configuration

• Pin A1 is the common ground GND.
• Pin A2 is the enable input pin EN.
• Pin B1 is the output pin Vout.
• Pin B2 is the input pin, Vin.

• Pin-1 is the input pin IN.
• Pin-2 is the common ground GND.
• Pin-3 is Enable input EN.
• Pin-4 doesn’t have any internal connection.
• Pin-5 is the output pin OUT.

• Pin-1 is the voltage output OUT.
• Pin-2 is the common ground GND.
• Pin-3 doesn’t have any internal connection.
• Pin-4 doesn’t have any internal connection.
• Pin-5 is the Enable input EN.
• Pin-6 is the voltage supply input IN.

Applications of LP3990

• Used in portable, battery-powered systems.
• This device is applied in Cellular Handsets.
• Hand-held portable systems use this IC.