MIC706P/R/S/T, MIC708R/S/T µP Supervisory Circuit General Description Features The MIC706 and MIC708 are inexpensive microprocessor • Maximum supply current: 30µA supervisory circuits that monitor power supplies in 3.0V • Debounced manual reset input is TTL/CMOS and 3.3V microprocessor-based systems. The circuit compatible functions include a watchdog timer, microprocessor reset, • Reset pulse width: 200ms power-failure warning, and a debounced manual reset input. • Watchdog timer: 1.6s (MIC706) • Precision supply voltage monitor The MIC706 offers a watchdog timer function, while the • Easy power-fail warning or low-battery detect MIC708 has an active-high reset output in addition to the active-low reset output. Applications The R, S, and T versions are similar in all respects except • Laptop and desktop computers for supply voltage reset threshold levels. The threshold levels are 2.63, 2.93, and 3.08V, respectively. When the • Intelligent systems supply voltage drops below the reset threshold level, • Critical microprocessor power monitoring /RESET (and RESET for the MIC708) is asserted. • Printers The MIC706P is identical to the MIC706R, except that the • Controllers Reset output is asserted high. Datasheets and support documentation are available on Micrel’s 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 • http://www.micrel.com May 28, 2014 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T Ordering Information Part Number Threshold (V) /RESET RESET WDI Junction Temperature Range Package MIC706PMY 2.63 √ √ –40°C to +85°C 8-Pin SOIC MIC706RMY 2.63 √ √ –40°C to +85°C 8-Pin SOIC MIC706SMY 2.93 √ √ –40°C to +85°C 8-Pin SOIC MIC706TMY 3.08 √ √ –40°C to +85°C 8-Pin SOIC MIC708RMY 2.63 √ √ –40°C to +85°C 8-Pin SOIC MIC708SMY 2.93 √ √ –40°C to +85°C 8-Pin SOIC MIC708TMY 3.08 √ √ –40°C to +85°C 8-Pin SOIC Pin Configuration MIC706 MIC708 8-Pin SOIC (M) 8-Pin SOIC (M) (Top View) (Top View) Pin Description Pin Number Pin Number Pin Name Pin Name MIC706 MIC708 Manual reset input forces reset outputs to assert when pulled below 0.8V. An 1 1 /MR internal pull-up current of 250µA on this input forces it high when left floating. This input can also be driven from TTL or CMOS logic. 2 2 VCC Primary supply input, +5V. 3 3 GND IC ground pin, 0V reference. Power-Fail Input: Internally-connected to the power-fail comparator which is referenced to 1.25V. The power-fail output (/PFO) remains high if PFI is above 4 4 PFI 1.25V. PFI should be connected to GND or VOUT if the power-fail comparator is not used. Power-Fail Output: The power-fail comparator is independent of all other function 5 5 /PFO on this device. Watchdog Input. The WDI input monitors microprocessor activity; an internal watchdog timer resets itself with each transition on the watchdog input. If the WDI 6 N/A WDI pin is held high or low for longer than the watchdog timeout period, /WDO is forced to active low. The watchdog function can be disabled by floating the WDI pin. N/A 6 N/C Not internally connected. May 28, 2014 2 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T Pin Description (Continued) Pin Number Pin Number Pin Name Pin Name MIC706 MIC708 /RESET is asserted if either VCC goes below the reset threshold voltage or by low signal on the manual reset input (/MR). /RESET remains asserted for one reset 7 7 /RESET timeout period (200ms) after VCC exceeds the reset threshold voltage or after the manual reset pin transition from low to high. The watchdog timer will not assert /RESET unless /WDO is connected to /MR. Output for the watchdog timer. The watchdog timer resets itself with each transition to the watchdog input. If the WDI pin is held high or low for longer than the 8 N/A /WDO watchdog timeout period, /WDO is forced low. /WDO will also be forced low if VCC is below the reset threshold voltage and will remain low until VCC returns to a valid level. RESET is the compliment of /RESET and is asserted if either VCC goes below the 7 8 RESET reset threshold voltage or by a low signal on the manual reset input (/MR). RESET (MIC706P) is suitable for microprocessor systems that use active high reset. May 28, 2014 3 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T (1) (2) Absolute Maximum Ratings Operating Ratings Terminal Voltage Operating Temperature Range ................... –40°C to +85°C V ......................................................... −0.3V to +6.0V Power Dissipation (SOP) ......................................... 400mW CC All Other Inputs. ........................... −0.3V to (V + 0.3V) Thermal Resistance CC Input Current 8-Pin SOIC ....................................................... 150°C/W V , GND .............................................................. 25mA CC Output Current (All) ..................................................... 20mA Lead Temperature (soldering, 10s) ............................ 300°C Storage Temperature (T ) ......................... −65°C to +150°C S (3) Electrical Characteristics VCC = 2.70V to 5.5V for MIC70_P/R; VCC = 3.00V to 5.5V for MIC70_S; VCC = 3.15V to 5.5V for MIC70_T. TA = Operating Temperature Range, bold values indicate –40°C ≤ TA ≤ +85°C, unless noted. Parameter Condition Min. Typ. Max. Units Operating Voltage Range 1.4 5.5 V Supply Current 30 µA MIC70_P/R 2.55 2.63 2.70 Reset Voltage Threshold MIC70_S 2.85 2.93 3.00 V MIC70_T 3.00 3.08 3.15 Reset Threshold Hysteresis 20 mV Reset Pulse Width (tRS) 140 200 280 ms ISOURCE = 200µA 0.8 × VCC /RESET Output Voltage (MIC70_R/S/T) ISINK = 1.2mA 0.3 V ISINK = 50µA, VCC = 1.4V 0.3 ISOURCE = 200µA 0.8 × VCC RESET Output Voltage (MIC706P) V ISINK = 1.2mA 0.3 ISOURCE = 200µA 0.8 × VCC RESET Output Voltage (MIC708R/S/T) V ISINK = 500µA 0.3 Watchdog Timeout Period (tWD) 1.0 1.6 2.25 s VIL = 0.4V, VIH = 80% of VCC 100 WDI Minimum Input Pulse (tWP) ns VIL = 0.4V, VIH = 80% of VCC > 4.5V 50 VIH 0.7 × VCC WDI Threshold Voltage V VIL 0.6 WDI Input Current WDI = 0V or VCC −1 1 µA ISOURCE = 200µA 0.8 × VCC WDO Output Voltage V ISINK = 500µA 0.3 /MR Pull-Up Current /MR = 0V 20 250 600 µA Notes: 1. Exceeding the absolute maximum ratings may damage the device. 2. The device is not guaranteed to function outside its operating ratings. 3. Specification for packaged product only. May 28, 2014 4 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T (3) Electrical Characteristics (Continued) VCC = 2.70V to 5.5V for MIC70_P/R; VCC = 3.00V to 5.5V for MIC70_S; VCC = 3.15V to 5.5V for MIC70_T. TA = Operating Temperature Range, bold values indicate –40°C ≤ TA ≤ +85°C, unless noted. Parameter Condition Min. Typ. Max. Units 500 /MR Pulse Width (tMR) VCC > 4.5V ns 150 VIL 0.6 /MR Input Threshold V VIH 0.7 × VCC /MR-to-Reset Output Delay (tMD) 750 ns PFI Input Threshold 1.2 1.25 1.3 V PFI Input Current −25 0.01 +25 nA ISINK = 1.2mA 0.3 /PFO Output Voltage V ISOURCE = 200µA 0.8 × VCC May 28, 2014 5 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T Timing Diagram Figure 1. Timing Diagram for Reset May 28, 2014 6 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T Block Diagram MIC706 Block Diagram MIC708 Block Diagram May 28, 2014 7 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T Watchdog Timer Application Information The microprocessor can be monitored by connecting the An additional comparator which is independent of the WDI pin (watchdog input) to a bus line or an I/O line. If a other functions on the MIC706P and MIC708 is provided transition doesn't occur on the WDI pin within in the for early warning of power failure. An external voltage watchdog timeout period, then /WDO will go low. A divider can be used to compare unregulated DC to an minimum pulse of 100ns or any transition low-to-high or internal 1.25V reference. The voltage divider ratio on the high-to-low on the WDI pin will reset the watchdog timer. input of the power-fail comparator (PFI) can be chosen so The output of the watchdog timer (/WDO) will remain high as to trip the power-fail comparator a few milliseconds if WDI sees a valid transition within the watchdog period. before V falls below the maximum reset threshold If VCC falls below the reset threshold voltage, then /WDO CC voltage. The output of the power-fail comparator (/PFO) goes low immediately regardless of WDI. /WDO can be can be used to interrupt the microprocessor when used in connected to /MR to generate a reset pulse upon this mode and execute shutdown procedures prior to watchdog timeout. power loss. Hysteresis can be added to this comparator with external resistors, as is commonly done with any Microprocessor Reset comparator. The /RESET pin is asserted whenever VCC falls below the reset threshold voltage or when /MR goes low. The reset pin remains asserted for a period of 200ms after VCC has risen above the reset threshold voltage and /MR goes high. 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. Figure 2. Power-Fail Comparator May 28, 2014 8 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T (4) Package Information and Recommended Landing Pattern 8-Pin SOIC (M) Note: 4. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com. May 28, 2014 9 Revision 2.0

Micrel, Inc. MIC706P/R/S/, MIC708R/S/T 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 makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. 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. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. 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. © 2000 Micrel, Incorporated. May 28, 2014 10 Revision 2.0

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M icrochip: MIC706MY MIC706PMY MIC706PMY TR MIC706RMY MIC706RMY TR MIC706SMY MIC706TMY MIC706TMY TR MIC708RMY MIC708RMY TR MIC708SMY MIC708SMY TR MIC708TMY MIC708TMY TR MIC708MY-TR MIC706RMY-TR MIC708TMY-TR MIC708RMY-TR MIC706TMY-TR MIC706SMY-TR MIC706PMY-TR MIC706MY- TR MIC708SMY-TR