MIC809/810
Microprocessor Reset Circuits
General Description
The MIC809 and MIC810 are inexpensive microprocessor
supervisory circuits that monitor power supplies in micro-
processor based systems.
The function of these devices is to assert a reset if the power
supply drops below a designated reset threshold level. Several
different reset threshold levels are available to accommodate
3V, 3.3V or 5V powered systems.
The MIC809 has an active-low /RESET output, while the
MIC810 offers an active-high RESET output. The reset output
is guaranteed to remain asserted for a minimum of 140ms
after V
CC
has risen above the designated reset threshold
level. Having a push-pull output stage, the MIC809/810 does
not require a pull-up resistor at the output. The MIC809/810
comes in a 3-pin SOT-23 and SC-70 package.
The MIC809 is also available with a shorter reset timeout
(30ms min.). See the MIC809-5.
All support documentation can be found on Micrel’s web site
at www.micrel.com.
Features
• Precision voltage monitor for 3V, 3.3V or 5V power sup-
plies
• /RESET remains valid with V
CC
as low as 1.4V for SOT-
23 packaged part
• /RESET remains valid with VCC as low as 1V for SC70
packaged part
• Typically less than15µA supply current for SOT-23 pack-
aged part
• 5µ typical supply current for SC70 packaged part
• 140ms minimum reset pulse widths available
• Available in 3-pin SOT-23 and SC-70 package
Applications
•
•
•
•
•
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Controllers
Typical Application
VCC
VCC
VCC
µP
RESET
MIC809
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
April 2005
1
M0450-041405
MICREL [ MICREL SEMICONDUCTOR ]
