MIC8115 Microprocessor Reset Circuit General Description Features The MIC8115 is an inexpensive microprocessor supervisory circuit that monitors power supplies in microprocessor-based systems. • • • • • • • The function of the MIC8115 is to assert a reset if the power supply drops below a designated reset threshold level or /MR is forced low. The MIC8115 has an active low /RESET output is guaranteed to remain asserted 1100ms after VCC has risen above the threshold level. The MIC8115 comes in package. output. The reset for a minimum of designated reset a 4-pin SOT-143 Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Precision voltage monitor for 3.3V power supplies Specifically-tailored to the AMD Elan SC500 Series /RESET remains valid with VCC as low as 1.4V <15µA supply current 1100ms minimum reset pulse width Manual reset input Available in 4-Pin SOT-143 Package Applications • • • • • Portable equipment Intelligent instruments Critical microprocessor power monitoring Printers/computers Embedded 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 August 3, 2015 Revision 2.0 Micrel, Inc. MIC8115 Ordering Information (1) Part Number Marking Junction Temperature Range Package Lead Finish MIC8115-TUY NT –40°C to +85°C 4-Pin SOT-143 Pb-Free Note: 1. Underbar (__) may not be to scale. Pin Configuration 4-Pin SOT-143 (Top View) Pin Description Pin Number Pin Name Pin Function 1 GND IC Ground Pin. 2 /RESET 3 /MR Manual Reset Input. A logic low on /MR forces a reset. The reset will remain asserted as long as /MR is held low and for one reset timeout period (1100ms, minimum) after /MR goes high. This input can be shorted to ground via a switch or driven from CMOS or TTL logic. Pulled high internally through a 20kΩ resistor. Float if unused. 4 VCC Power Supply Input. August 3, 2015 /RESET goes low if either VCC falls below the supply reset threshold voltage or if /MR is asserted. /RESET remains asserted for one reset timeout period 1100ms (minimum) after both VCC exceeds the supply reset threshold voltage and /MR is deasserted. 2 Revision 2.0 Micrel, Inc. MIC8115 Absolute Maximum Ratings(2) Operating Ratings(3) Terminal Voltage (VCC) ......................................................... –0.3V to 6.0V (/MR) ............................................... –0.3V (VCC + 0.3V) Input Current (VCC, /MR) ............................................ 20mA Output Current (/RESET) ............................................ 20mA Rate of Rise (VCC) ................................................... 100V/µs Lead Temperature (soldering, 10s) ............................ 300°C Storage Temperature (TS) ......................... –65°C to +150°C (4) ESD Rating .................................................................. 3kV Operating Temperature Range .................. –40°C to +85°C Power Dissipation (TA = +70°C) ............................... 320mW Electrical Characteristics For typical values, VCC = 3.3V; TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C, unless noted. Symbol Parameter Condition VCC Operating Voltage Range TA = –40°C to +85°C ICC Supply Current Min. Reset Voltage Threshold IRST Reset Timeout Period 1100 VOH /RESET Output Voltage VOL /Reset Output Voltage VIL /MR Input Threshold 5.5 V 5 15 µA 3.08 3.15 V 1700 2500 ms V VCC = VTH(MIN), ISINK = 1.2mA 0.3 VCC = 1V, ISINK = 50µA, TA = –40°C to +85°C 0.3 V 10 /MR to Reset Delay /MR Input Threshold Units 0.8 × VCC ISOURCE = 500µA /MR Minimum Pulse Width VIH Max. 1 3.00 VTH Typ. µs 0.5 µs 0.7 × VCC V 0.25 × VCC 10 /MR Pull-Up Resistance /MR Glitch Immunity 20 100 30 kΩ ns Notes: 2. Exceeding the absolute maximum ratings may damage the device. 3. The device is not guaranteed to function outside its operating ratings. 4. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF. August 3, 2015 3 Revision 2.0 Micrel, Inc. MIC8115 Timing Diagram Functional Diagram August 3, 2015 4 Revision 2.0 Micrel, Inc. MIC8115 Application Information Microprocessor Reset The /RESET pin is asserted whenever VCC falls below the reset threshold voltage. The reset pin remains asserted for a period of 1100ms after VCC has risen above the reset threshold voltage. The reset function ensures the microprocessor is properly reset and powers up into a known condition after a power failure. /RESET will remain valid with VCC as low as 1.4V. VCC Transients The MIC1815 is relatively immune to the negative-going VCC glitches below the reset threshold. Typically, a negative- going transient 125mV belt the reset threshold with duration of 20µs or less will not cause a reset. /RESET Valid at Low Voltage A resistor can be added from the /RESET pin to the ground to ensure the /RESET output remains low with VCC down to 0V. A 100kΩ resistor connected from /RESET to ground is recommended. The resistor should be large enough not to load the /RESET output and small enough to pull-down any stray leakage currents. Figure 1. /RESET Valid to VCC = 0V August 3, 2015 5 Revision 2.0 Micrel, Inc. MIC8115 Package Information and Recommended Landing Pattern(5) 4-Pin SOT-143 (TU) Note: 5. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com. August 3, 2015 6 Revision 2.0 Micrel, Inc. MIC8115 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products. Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network of distributors and reps worldwide. Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. 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