Linear Technology LTC691CSW#PBF - Microprocessor Supervisory Circuit

The LTC691CSW#PBF is a state-of-the-art microprocessor supervisory circuit designed by Linear Technology to ensure the reliable operation of microprocessor systems. This device monitors the power supply voltage of a microprocessor (μP) system, providing a reset signal to the processor upon detection of power failures. This feature ensures that the μP and its associated circuitry reset to a known state during power-up, power-down, or brownout conditions.

The LTC691CSW#PBF comes in a 16-pin surface-mount package, suitable for space-constrained applications. It offers a precise voltage monitor with a 4.65V threshold, ensuring accurate detection of under-voltage conditions. When the supply voltage falls below this threshold, the reset output is asserted, holding the microprocessor in a reset state for a minimum of 200ms after the supply voltage exceeds the reset threshold. This delay provides the power supply with sufficient time to stabilize before the processor starts operation.

Additionally, this supervisory circuit features a watchdog timer that can be set by an external capacitor. This timer periodically checks if the μP is operating correctly. If the μP fails to provide a periodic reset pulse to the LTC691CSW#PBF, it assumes that the μP is not functioning correctly and generates a system reset. This watchdog feature enhances the reliability of the system by ensuring that the μP does not hang in an indeterminate state.

The LTC691CSW#PBF also includes a manual reset input that allows for an external pushbutton or logic signal to initiate a system reset. This manual reset is debounced by the LTC691, providing clean reset signaling to the system.

With its wide operating temperature range and low supply current requirements, the LTC691CSW#PBF is an ideal choice for battery-operated and portable systems, as well as for more traditional μP-based applications in networking, telecommunications, and industrial control systems. Its robust feature set ensures that critical systems maintain operation integrity through various power supply conditions.

Linear Technology's commitment to high-quality and reliable circuit solutions is evident in the LTC691CSW#PBF, making it an essential component for designers looking to enhance the operational stability of their microprocessor systems.