IRU1117-33CPTR

IRU1117-33CPTR Application Field and Working Principle

IRU1117-33CPTR belongs to the PMIC (Power Management IC) Voltage Regulators – Linear category. It is a low drop-out voltage regulator designed to provide a 1.8V output from an input voltage as low as 1.20V, while still able to deliver up to 1A current. It uses a low-noise Micro-Power design, and its stability over the full load and temperature range is highly reliable.

The device integrates several high-performance functions such as active-down voltage step-down, voltage reference, and current limit functions. By using these functions, it can provide very stable output over a wide range of operating conditions. It also includes various protection measures such as over-temperature, under-voltage, reverse leakage current, and over-current protection.

Application wise, this device is applicable to battery-powered or wall-powered systems. It is widely used for processor power supplies, embedded systems, microcontrollers, disk drives, multimedia systems, portable electronic devices, digital consumer appliances, data communications, digital audio-video devices, and enterprise server system power supplies.

Working Principle

This device works on the principles of active-down voltage step-down and voltage reference. Its main components are the main power devices, two NPN transistors, two PNP transistors, two diodes, and a voltage reference. When the input voltage is greater than the output voltage, the PNP transistor is enabled, turning on the NPN transistor, which then pulls down the output of the regulator.

The voltage references consist of a series of current mirrors and bandgap references. When the output voltage is set, the voltage reference drives the drive circuit to supply the correct amount of current to the main power devices. This regulates the output voltage to maintain the desired level. The two diodes are used to protect the regulator from reverse current.

The main power devices comprise two PNP transistors and two NPN transistors. The PNP transistor is connected to the output side and is enabled when the input voltage is greater than the output voltage. The NPN transistors are connected to the input side, and when enabled, control the flow of current between the input and output sides.

The current limit circuit is the key component to protect the device from over-current events. It consists of a voltage-controlled current source and a current mirror circuit. When the voltage on the current source increases, it reduces the current in the current source and the output current, protecting the device from over-current events.