MIC811/812

Microprocessor Reset Circuits

General Description

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.

Datasheets and support documentation are available on

Micrel’s web site at: www.micrel.com.

Features

• 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

• Portable equipment

• Intelligent instruments

• Critical microprocessor power monitoring

• Printers/computers

• Controllers

Typical Application

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 9, 2014

Revision 2.0