BU4817FVE-TR

PMIC - Supervisors (BU4817FVE-TR)

Introduction

The BU4817FVE-TR is a supervisor IC that typically utilizes a voltage supervisor circuit with manual reset and watchdog timer reset functions at a nominal power supply voltage of 1.8V to 5.5V. It is widely used for reset circuits and 18V surge protection circuits. The supervisor IC is designed to detect low voltage, high voltage and power failure conditions on a battery or other power supplies.

Application Field

The BU4817FVE-TR supervisor IC has a wide variety of uses such as in CMOS cameras, digital still cameras, MP3 players, PDAs, portable cleaning equipment and air conditioners. It is also used in medical equipment, cellular phones, digital camcorders, handheld computers, home appliances, and other digital products, where low voltage and high voltage warning signals and reset signals are necessary.

Working Principle

The BU4817FVE-TR supervisor IC is a hybrid IC consisting of a voltage supervisor circuit and a reset circuit, along with a number of peripheral circuits such as a switch detection circuit and a power-on reset regenerating circuit. The voltage supervisor circuit utilizes two voltage detectors with hysteresis, one monitoring the power supply voltage and the other detecting the input voltage range, with the reset signal being output when either voltage exceeds a regulated limit. The reset signal can also be set with a time delay before it is output.

The reset circuit has two built-in reset circuits; a manual reset circuit with a pushbutton on the chip and a watchdog timer reset circuit. The manual reset circuit monitors the pushbutton and outputs a reset signal when the button is pressed. The watchdog timer reset circuit monitors the RESETN signal, and outputs a reset signal when the RESETN signal is constantly active for longer than the set timing.

The BU4817FVE-TR has two voltage detectors that are used to monitor both the power supply voltage and the input voltage range. Each voltage detector is accompanied by a hysteresis circuit that enables detection of small fluctuations in voltage. It also allows a minimum difference between the upper and lower hysteresis voltages for protection against a temporary voltage fluctuation caused by an interference or vibration. This ensures reliable power-on reset operation even in environments where fluctuations in voltage are common.

The watchdog timer reset circuit monitors the RESETN signal input, which is made active when the system is operating normally. The watchdog timer generates a reset signal when the RESETN signal remains active for longer than the set time, thus protecting the system against a system lock.

Conclusion

The BU4817FVE-TR supervisor IC is typically used in reset circuits and 18V surge protection circuits. It has built-in voltage detector and hysteresis circuits that detect low voltage, high voltage and power failure conditions on a battery or other power supplies, as well as two reset circuits to ensure reliable power-on reset even in environments with voltage fluctuations. The voltage detectors, hysteresis and reset circuits work together to provide reliable operation of a wide range of digital products.