MIC811/812
Micrel
MIC811/812
Microprocessor Reset Circuits
General Description
Features
The MIC811 and MIC812 are inexpensive microprocessor
supervisory circuits that monitor power supplies in microprocessor based systems.
The function of this device is to assert a reset if either the
power supply drops below a designated reset threshold
level or /MR is forced low. Several different reset threshold
levels are available to accommodate 3V, 3.3V or 5V powered
systems.
The MIC811 has an active low /RESET output, while the
MIC812 offers an active high RESET output. The reset output
is guaranteed to remain asserted for a minimum of 140ms
after VCC has risen above the designed reset threshold level.
Having a push-pull output stage, the MIC811/812 does not
require a pull-up resistor at the output. The MIC811/812
comes in a 4-pin SOT-143 package.
If a microprocessor voltage supervisor with an open-drain
output stage is needed, see MIC6315.
• Precision voltage monitor for 3V, 3.3V or 5V power supplies
• /RESET remains valid with VCC as low as 1V
• 5µA typical supply current
• 140ms minimum reset pulse width available
• Manual reset input
• Available in 4-pin SOT-143 package
Applications
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Typical Application
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Embedded controllers
VCC
VCC
VCC
MIC81 1
µP
MR
RESET
RESET
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
September 2005
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MIC811/812
