MIC811/812 Microprocessor Reset Circuits General Description Features The MIC811 and MIC812 are inexpensive microprocessor Precision voltage monitor for 3V, 3.3V or 5V power supervisory circuits that monitor power supplies in supplies microprocessor based systems. /RESET remains valid with VCC as low as 1V The function of this device is to assert a reset if either the 5A typical supply current power supply drops below a designated reset threshold 140ms minimum reset pulse width available level or /MR is forced low. Several different reset threshold Manual reset input levels are available to accommodate 3V, 3.3V or 5V Available in 4-pin SOT-143 package powered systems. Applications The MIC811 has an active low /RESET output, while the MIC812 offers an active high RESET output. The reset Portable equipment output is guaranteed to remain asserted for a minimum of Intelligent instruments 140ms after VCC has risen above the designed reset Critical microprocessor power monitoring threshold level. Having a push-pull output stage, the MIC811/812 does not require a pull-up resistor at the Printers/computers output. The MIC811/812 comes in a 4-pin SOT-143 Controllers package. If a microprocessor voltage supervisor with an open-drain output stage is needed, see MIC6315. Datasheets and support documentation are available on Micrels web site at: www.micrel.com. Typical Application Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC811/812 Ordering Information Part Number (1) Marking Threshold Voltage Operating Temp. Range Package Pb-Free MIC811LUY KL 4.63 40C to +85C 4-pin SOT-143 MIC811MUY KM 4.38 40C to +85C 4-pin SOT-143 MIC811JUY KJ 4.00 40C to +85C 4-pin SOT-143 MIC811TUY KT 3.08 40C to +85C 4-pin SOT-143 MIC811SUY KS 2.93 40C to +85C 4-pin SOT-143 MIC811RUY KR 2.63 40C to +85C 4-pin SOT-143 MIC812LUY LL 4.63 40C to +85C 4-pin SOT-143 MIC812MUY LM 4.38 40C to +85C 4-pin SOT-143 MIC812JUY LJ 4.00 40C to +85C 4-pin SOT-143 MIC812TUY LT 3.08 40C to +85C 4-pin SOT-143 MIC812SUY LS 2.93 40C to +85C 4-pin SOT-143 MIC812RUY LR 2.63 40C to +85C 4-pin SOT-143 Note: 1. underbar symbol not to scale Pin Configuration MIC811 4-Pin SOT-143 (U) MIC812 4-Pin SOT-143 (U) Pin Description MIC811 MIC812 Pin Name Pin Name 1 1 GND IC Ground Pin. /RESET goes low if VCC falls below the reset threshold and remains asserted 2 N/A /RESET for one reset timeout period (140ms min.) after VCC exceeds the reset threshold. RESET goes high if VCC falls below the reset threshold and remains asserted N/A 2 RESET for one reset timeout period (140ms min.) after VCC exceeds the reset threshold. Manual Reset Input. A logic low on /MR will force a reset. The reset will remain asserted as long as /MR is held low and for one reset timeout period 3 3 /MR (140ms min.) after /MR goes high. This input can be shorted to ground via a switch or driven from CMOS or TTL logic. Float if unused. 4 4 VCC Power Supply Input. Revision 2.0 September 9, 2014 2