Analog Devices

TheADM690A/ADM692A/ADM802L/M / ADM805L/M family of supervisory circuits offers complete single chip solutions for power supply monitoring and battery control functions in microprocessor systems. These functions include mP reset, backup battery switchover, watchdog timer, and power failure warning.The ADM690A / ADM692A / ADM802L/M / ADM805L/M are available in 8-pin packages and provide:Power-on reset output during power-up, power-down and brownout conditions. TheRESEToutput remains operational with VCCas low as 1 V.Battery backup switching for CMOS RAM, CMOS microprocessor or other low power devices.A reset pulse if the optional watchdog timer has not been toggled within 1.6 seconds.A 1.25 V threshold detector for power fail warning, low battery detection, or to monitor a power supply other than +5 V.On the ADM690A / ADM802L / ADM805L the reset voltage threshold is 4.65 V. On the ADM692A / ADM802M / ADM805M, the reset voltage threshold is 4.40 V.The ADM802L / ADM802M guarantee power fail accuracies to ±2%.

The ADM811/ADM812are reliable voltage monitoring devices suitable for use in most voltage monitoring applications. The ADM811/ADM812 are designed to monitor six different voltages, each allowing a 5% or 10% degradation of standard PSU voltages before a reset occurs. These voltages have been selected for the effective monitoring of 2.5 V, 3 V, 3.3 V, and 5 V supply voltage levels.Included in this circuit is a debounced manual reset input. Reset can be activated using an electrical switch (or an input from another digital device) or by a degradation of the supply voltage. The manual reset function is very useful, especially if the circuit in which the ADM811/ADM812 are operating enters into a state that can only be detected by the user. Allowing the user to reset a system manually can reduce the damage or danger that could otherwise be caused by an out-of-control or locked system.ApplicationsMicroprocessor systemsControllersIntelligent instrumentsAutomotive systemsSafety systemsPortable instruments

TheADM811/ADM812 are reliable voltage monitoring devices suitable for use in most voltage monitoring applications. The ADM811/ADM812 are designed to monitor six different voltages, each allowing a 5% or 10% degradation of standard PSU voltages before a reset occurs. These voltages have been selected for the effective monitoring of 2.5 V, 3 V, 3.3 V, and 5 V supply voltage levels.Included in this circuit is a debounced manual reset input. Reset can be activated using an electrical switch (or an input from another digital device) or by a degradation of the supply voltage. The manual reset function is very useful, especially if the circuit in which the ADM811/ADM812 are operating enters into a state that can only be detected by the user. Allowing the user to reset a system manually can reduce the damage or danger that could otherwise be caused by an out-of-control or locked system.ApplicationsMicroprocessor systemsControllersIntelligent instrumentsAutomotive systemsSafety systemsPortable instruments

TheADM823/ ADM824 /ADM825are supervisory circuits that monitor power supply voltage levels and code execution integrity in microprocessor-based systems. In addition to providing power-on reset signals, an on-chip watchdog timer can reset the microprocessor if it fails to strobe within a preset timeout period. A reset signal can also be asserted by an external push-button, through a manual reset input. The three parts feature different combinations of watchdog input, manual reset input, and output stage configuration, as shown in Table 1.These parts are available in a choice of seven reset threshold options ranging from 2.19 V to 4.63 V. The reset and watchdog timeout periods are fixed at 140 ms (minimum) and 1.6 sec (typical), respectively.The ADM823 / ADM824 / ADM825 are available in 5-lead SC70 and SOT-23 packages and typically consume only 5 μA, making them suitable for use in low power, portable applications.APPLICATIONSMicroprocessor systemsComputersControllersIntelligent instrumentsPortable equipment