April 2005

1

M0450-041405

MIC809/810

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

supplydropsbelowadesignatedresetthresholdlevel.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 RESEToutput.The reset output

is guaranteed to remain asserted for a minimum of 140ms

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.

Typical Application

VCC

RESET

µP

RESET

VCC

MIC809

VCC

• Precision voltage monitor for 3V, 3.3V or 5V power sup-

plies

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

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com