CN809S

The CN803/809/810 series are microprocessor reset circuits designed to monitor supply voltage or battery voltage. These circuits require no external components, improving system reliability and reducing system cost. This series asserts a valid reset signal when the monitored supply voltage falls below the preset reset threshold; when the supply voltage rises above the reset threshold, the reset signal remains asserted for a minimum of 140 ms. CN809/810 provide CMOS reset outputs, while CN803 provides an open-drain output. CN803 and CN809 are active-low reset outputs, and CN810 is an active-high reset output. The design ensures that brief supply voltage glitches do not affect the reset output. Guaranteed valid output is maintained over the entire temperature range with supply voltage as low as 1.15V. The devices in this series are available in a 3-pin SOT23 package. The CN803/809/810 series are primarily used to monitor the power supplies of microprocessors, microcontrollers, memories, and other digital circuits, providing reset signals during power-up, power-down, or when the supply voltage falls below the reset threshold, ensuring these devices operate in a known state and preventing the execution of erroneous code. The circuit internally comprises a voltage comparator, a low-power voltage reference, a resistor divider network, an output delay circuit, and an output driver circuit. The CN803/809/810 series assert a valid reset signal when the supply voltage falls below the reset threshold. After the supply voltage rises above the sum of the reset threshold and the reset threshold hysteresis, the reset output remains asserted for a minimum of 140 ms. CN809/810 provide CMOS outputs, while CN803 provides an open-drain output. CN803/809 provide active-low reset outputs, while CN810 provides an active-high reset output. The design ensures that brief supply voltage glitches do not affect the reset output. Guaranteed valid output is maintained over the entire operating temperature range with supply voltage as low as 1.15V.

Applications

• Computers
• Microcontrollers
• Smart meters
• Portable or battery-powered devices

Key features

• Precision reset threshold: ±2.5%
• Two reset output options: -CMOS output (CN809/CN810) -Open-drain output (CN803)
• Minimum reset pulse width: 140ms
• Low operating current: 3.2μA typical at 3V
• Reset signal remains reliable down to 1.15V supply voltage
• Power supply glitch filtering
• Operating temperature range: -40°C to +85°C
• SOT23-3 package