3-Pin Microprocessor Reset Circuits
The MCP809/810 microprocessor supervisory circuits can
be used to monitor the power supplies in microprocessor
and digital systems. They provide a reset to the micropro-
cessor during power-up, power-down and brown-out condi-
The function of the MCP809/810 is to monitor the VCC
supply voltage, and assert a reset signal whenever this
voltage declines below the factory-programmed reset
threshold. The reset signal remains asserted for 240ms after
VCC rises above the threshold. The MCP809 has an
active-low RESET output, while the MCP810 has an
active-high RESET output.
Seven standard reset voltage options are available, suitable
for monitoring 5V, 3.3V, and 3V supply voltages.
With a low supply current of only 15µA, the MCP809/810 are
ideal for use in portable equipment. The MCP809/MCP810
are available in the 3-pin SOT23 package.
n Precise monitoring of 3V, 3.3V, and 5V supply voltages
n Fully specified over temperature
n 140ms min. Power-On Reset pulse width, 240ms typical
Active-low RESET Output (MCP809)
Active-high RESET Output (MCP810)
n Guaranteed RESET Output valid for VCC≥1V
n Low Supply Current, 15µA typ.
n Power supply transient immunity
n Microprocessor Systems
n Intelligent Instruments
n Portable/Battery-Powered Equipment
Typical Application Circuit
( ) are for MCP810
© 2001 National Semiconductor Corporation DS200223