UC3903N

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UC3903N is one of the primary PMIC supervisors (PMICs) for providing solutions in applications such as system power-on reset and over-voltage protection. The UC3903N device includes a microprocessor supervisor, a resettable latch, a comparator, a controlled voltage regulator, and an oscillator, all in one integrated chip. It also provides reset, power-on reset, input protection, pull-up, and stable voltages. Additionally, with its flexible and configurable features, it is suitable for low-cost, high-efficiency solutions. Let us now look at the application field and the working of the UC3903N.

Application Field

The UC3903N has many applications in the field of embedded systems and computing platforms. These applications involve a combination of analog, digital, and mixed-signal methods. It offers solutions for reset of the system clock, reset of memory, reset of peripherals, indication of device operation, power management, input protection, and over-voltage protection. It is especially suitable for applications such as power supply switching and USB-based solutions. Additionally, it can be utilized for high-speed serial buses, bi-directional level shifting, and RF applications.

Working Principle

The UC3903N works by employing a microprocessor reset module, resettable latch, comparator, and regulated voltage regulator. Its integrated microprocessor reset circuit features a programmable delay between power-on and the start of resets. This delay can be stated both in terms of time or in terms of voltage. The delay time is programmable over a range of milliseconds up to two seconds; and the delay voltage is programmable over a range of 1V to 5V.

The UC3903N has an inbuilt resettable latch, which works by capturing the reset state when a high-frequency clock triangle wave is applied to the triangle wave input pin. The latch then provides a constant output until a reset signal is applied. This ensures that during reset, the circuit remains stable and a correct reset can occur.

The comparator works by comparing the voltage level of two different inputs. If the two levels are the same, the comparator will produce an output voltage level; otherwise, it will remain inactive. The UC3903N includes a controlled voltage regulator, which acts as a voltage source that is regulated to a certain level. This helps to ensure that the voltage is not exceeded when the system is in reset.

The device also features an oscillator input pin, which enables the clock frequency to be changed. With the adjustable oscillator, the timer and reset delay can be modified over a wide range of frequencies. Additionally, the oscillator enables the reset time to be set to a range of 0.25ms to 2s.

The UC3903N offer flexible and configurable features that make it suitable for low-cost, high-efficiency solutions. With its many applications and its simple yet powerful design, the UC3903N is an invaluable PMIC supervisor. It can be used to serve a wide range of purposes, including system power-on reset, over-voltage protection, input protection, and reset indication.

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