MIC705/706/707/708 P Supervisory Circuit General Description Features The MIC705, MIC706, MIC707, and MIC708 are Debounced manual reset input is TTL/CMOS inexpensive microprocessor supervisory circuits that compatible monitor power supplies in microprocessor-based systems. Reset pulse width: 200ms The circuit functions include a watchdog timer, Watchdog timer: 1.6s (MIC705/706) microprocessor reset, power-failure warning, and a 4.65V or 4.40V precision voltage monitor debounced manual reset input. Early power-fail warning or low-battery detect The MIC705 and MIC706 offer a watchdog timer function while the MIC707 and MIC708 have an active-high reset Applications output in addition to the active-low reset output. Automotive systems Supply voltage monitor levels of 4.65V and 4.4V are Intelligent systems available. The MIC705 and MIC707 have a nominal reset Critical microprocessor power monitoring threshold level of 4.65V while the MIC706 and MIC708 have a 4.4V nominal reset threshold level. When the Battery-powered computers supply voltage drops below the respective reset threshold Computers level, /RESET is asserted. Controllers 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. MIC705/706/707/708 Ordering Information Part Number Threshold (V) /RESET RESET WDI Junction Temperature Range Package MIC705MY 4.65 8-Pin SOIC 40C to +85C MIC706MY 4.40 40C to +85C 8-Pin SOIC MIC707MY 4.65 40C to +85C 8-Pin SOIC MIC708MY 4.40 40C to +85C 8-Pin SOIC Pin Configuration MIC705/706 MIC707/708 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 to assert when pulled below 0.8V. An internal 1 1 /MR pull-up current of 250A 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 VCC 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. Revision 2.1 September 15, 2014 2