MIC811/812 Micrel, Inc. MIC811/812 Microprocessor Reset Circuits Final Information General Description Features The MIC811 and MIC812 are inexpensive microprocessor supervisory circuit that monitors 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, 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. * Precision voltage monitor for 3V, 3.3V or 5V power supplies * /RESET remains valid with VCC as low as 1.4V * <15A 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 Embedded controllers Ordering Information Standard Part Number Marking Pb-Free Part Number Marking Threshold Voltage Operating Temp. Range MIC811LU KL MIC811LUY KL Package 4.63 -40C to +85C 4-lead SOT-143 MIC811MU KM MIC811MUY KM MIC811JU KJ MIC811JUY KJ 4.38 -40C to +85C 4-lead SOT-143 4.00 -40C to +85C 4-lead SOT-143 MIC811UU KU MIC811UUY KU 3.00 -40C to +85C 4-lead SOT-143 MIC811TU KT MIC811TUY KT 3.08 -40C to +85C 4-lead SOT-143 MIC811SU KS MIC811SUY KS 2.93 -40C to +85C 4-lead SOT-143 MIC811RU KR MIC811RUY KR 2.63 -40C to +85C 4-lead SOT-143 MIC812LU LL MIC812LUY LL 4.63 -40C to +85C 4-lead SOT-143 MIC812MU LM MIC812MUY LM 4.38 -40C to +85C 4-lead SOT-143 MIC812JU LJ MIC812JUY LJ 4.00 -40C to +85C 4-lead SOT-143 MIC812UU LU MIC812UUY LU 3.00 -40C to +85C 4-lead SOT-143 MIC812TU LT MIC812TUY LT 3.08 -40C to +85C 4-lead SOT-143 MIC812SU LS MIC812SUY LS 2.93 -40C to +85C 4-lead SOT-143 MIC812RU LR MIC812RUY LR 2.63 -40C to +85C 4-lead SOT-143 *Under bar symbol (_) may not be to scale. Typical Application VCC VCC VCC MIC811 P MR RESET 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 February 2005 1 MIC811/812 MIC811/812 Micrel, Inc. Pin Configuration GND 1 4 VCC MIC811 RESET 2 3 MR GND 1 4 VCC MIC812 RESET 2 3 MR MIC811 4-Lead SOT-143 MIC812 4-Lead SOT-143 Pin Description Pin Number MIC811 Pin Number MIC812 Pin Name Pin Function 1 1 GND IC Ground Pin 2 N/A /RESET /RESET goes low if VCC falls below the reset threshold and remains asserted for one reset timeout period (140ms min.) after VCC exceeds the reset threshold N/A 2 RESET RESET goes high if VCC falls below the reset threshold and remains asserted for one reset timeout period (140ms min.) after VCC exceeds the reset threshold 3 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 (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. MIC811/812 2 February 2005 MIC811/812 Micrel, Inc. Absolute Maximum Ratings(Note 1) Operating Ratings(Note 2) Terminal Voltage (VCC) ............................... -0.3V to +6.0V Input Current (VCC, /MR) ............................................ 20mA Output Current (/RESET, RESET) ............................. 20mA Lead Temperature (soldering, 10 sec.) ..................... 300C Storage Temperature (TS) ......................... -65C to 150C Rate of Rise (VCC) ................................................. 100V/s ESD Rating, Note 3 Operating Temperature Range MIC811 ..................................................... -40C to 85C MIC812 ..................................................... -40C to 85C Power Dissipation (TA = +70C) .............................. 320mW Electrical Characteristics For typical values, VCC = 5V for MIC8_L/M/J, VCC = 3.3V for MIC8_S/T, VCC = 3V for MIC8_R; TA = 25C, bold values indicate -40C TA +85C; unless noted Symbol Parameter Condition Min VCC Operating Voltage Range TA = 0C to 70C TA = -40C to 85C ICC VTH Supply Current Reset Voltage Threshold tRST Reset Timeout Period VOH /RESET Output Voltage VOL /RESET Output Voltage Typ Max Units 1.4 5.5 V 1.6 5.5 V MIC811L/M/J, MIC812L/M/J: VCC = 5.0V, no load 9 15 A MIC811S/T, MIC812S/T VCC = 3.3V, no load 6 10 A MIC811R, MIC812R: VCC = 3.0V, no load MIC811L, MIC812L 6 10 A 4.50 4.63 4.75 V MIC811M, MIC812M 4.25 4.38 4.50 V MIC811J, MIC812J 3.89 4.00 4.10 V MIC811T, MIC812T 3.00 3.08 3.15 V MIC811S, MIC812S 2.85 2.93 3.00 V MIC811R, MIC812R 2.55 2.63 2.70 V 140 240 560 ms ISOURCE = 800A, MIC811L/M/J VCC-1.5V V ISOURCE = 500A, MIC811R/S/T 0.8x xVCC V VCC = VTH min., ISINK = 3.2mA, MIC811L/M/J 0.4 V VCC = VTH min., ISINK = 1.2mA, MIC811R/S/T 0.3 V VCC > 1.4V, ISINK = 50A, TA = 0C to +70C 0.3 V VCC > 1.6V, ISINK = 50A, TA = -40 to +85C 0.3 V VOH RESET Output Voltage 1.8V < VCC < VTH min., ISOURCE = 150A VOL RESET Output Voltage ISINK = 3.2mA, MIC812L/M/J 0.4 V ISINK = 1.2mA, MIC812R/S/T 0.3 V /MR Minimum Pulse Width 0.8x xVCC 10 /MR to Reset Delay VIH /MR Input Threshold /MR Input Threshold s 0.5 VCC > VTH max., MIC81_L/M/J MIC81_R/S/T VIL V 2.3 V 0.7x xVCC V VCC . VTH max., MIC81-L/M/_ 0.8 MIC81_R/S/T V 0.25x xVCC /MR Pull-Up Resistance 10 /MR Glitch Immunity Note 1. Note 2. Note 3. s 20 100 30 k ns Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. February 2005 3 MIC811/812 MIC811/812 Micrel, Inc. Timing Diagram VCC VTH /MR tRST tRST /RESET Reset Timing Diagram Functional Diagram MIC811/812 4 February 2005 MIC811/812 Micrel, Inc. /RESET Valid at Low Voltage A resistor can be added from the /RESET pin to ground to ensure the /RESET output remains low with VCC down to 0V. A 100k resistor connected from the /RESET to ground is recommended. The size of the resistor should be large enough not to load the output excessively and small enough to pull-down any stray leakage currents. Applications Information Microprocessor Reset The /RESET (or RESET) pin is asserted whenever VCC falls below the reset threshold voltage. The /RESET pin remains asserted for a period of 140ms after VCC has risen above the reset threshold voltage. The reset function ensures the microprocessor is properly reset and powers up in a known condition after a power failure. /RESET will remain valid with VCC as low as 1.4V. VCC Transients The MIC811/812 are relatively immune to negative-going VCC glitches below the reset threshold. Typically, a negativegoing transient 125mV below the reset threshold with a duration of 50s (25s for MIC8_R/S/T) or less will not cause a reset. Interfacing to Bidirectional Reset Pins The MIC811/812 can interface with Ps with bidirectional reset pins by connecting a 4.7k resistor in series with the MIC811/812 output and the P reset pin. February 2005 VCC VCC VCC MIC811 P RESET RESET 100K Reset Valid to VCC = 0V 5 MIC811/812 MIC811/812 Micrel, Inc. Package Information 0.950 (0.0374) TYP 1.40 (0.055) 2.50 (0.098) 1.20 (0.047) 2.10 (0.083) CL CL DIMENSIONS: MM (INCH) 1.12 (0.044) 0.81 (0.032) 3.05 (0.120) 2.67 (0.105) 0.800 (0.031) TYP 0.400 (0.016) TYP 3 PLACES 8 0 0.10 (0.004) 0.013 (0.0005) 0.150 (0.0059) 0.089 (0.0035) 0.41 (0.016) 0.13 (0.005) 4-lead SOT-143 (M3) 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 This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2003 Micrel, Incorporated. MIC811/812 6 February 2005