Analog Devices Inc./Maxim Integrated

The DS1705/DS1706 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor: power supply, software execution, and external override. A precision temperature compensated reference and comparator circuit monitor the status of VCCat the device and at an upstream point for maximum protection. When the sense input detects an out-of-tolerance condition a non-maskable interrupt is generated. As the voltage at the device degrades, an internal power fail signal is generated which forces the reset to an active state. When VCCreturns to an in-tolerance condition, the reset signal is kept in the active state for a minimum of 130ms to allow the power supply and processor to stabilize.The second function the DS1705/DS1706 performs is pushbutton reset control. The DS1705/DS1706 debounces the pushbutton input and guarantees an active reset pulse width of 130ms minimum.The third function is a watchdog timer. The DS1705/DS1706 has an internal timer that forces the WDO signal to the active state if the strobe input is not driven low prior to time-out.

The DS1705/DS1706 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor: power supply, software execution, and external override. A precision temperature compensated reference and comparator circuit monitor the status of VCCat the device and at an upstream point for maximum protection. When the sense input detects an out-of-tolerance condition a non-maskable interrupt is generated. As the voltage at the device degrades, an internal power fail signal is generated which forces the reset to an active state. When VCCreturns to an in-tolerance condition, the reset signal is kept in the active state for a minimum of 130ms to allow the power supply and processor to stabilize.The second function the DS1705/DS1706 performs is pushbutton reset control. The DS1705/DS1706 debounces the pushbutton input and guarantees an active reset pulse width of 130ms minimum.The third function is a watchdog timer. The DS1705/DS1706 has an internal timer that forces the WDO signal to the active state if the strobe input is not driven low prior to time-out.

The DS1720 Digital Thermometer and Thermostat provides 9-bit temperature readings which indicate the temperature of the device. With three thermal alarm outputs, the DS1720 can also act as a thermostat. THIGHis driven high if the DS1720's temperature is greater than or equal to a user-defined temperature TH. TLOWis driven high if the DS1720's temperature is less than or equal to a user-defined temperature TL. TCOMis driven high when the temperature exceeds THand stays high until the temperature falls below that of TL.User-defined temperature settings are stored in non-volatile memory, so parts can be programmed prior to insertion in a system, as well as used in stand-alone applications without a CPU. Temperature settings and temperature readings are all communicated to/from the DS1720 over a simple 3-wire interface.ApplicationsConsumer ProductsIndustrial SystemsThermally Sensitive SystemsThermometersThermostatic Controls

The DS1721 digital thermometer and thermostat features ±1°C accuracy over a -10°C to +85°C range. Thermometer data is read out over a 2-wire serial bus in 2's complement format with 9 to 12 bits of resolution (user-programmable). The DS1721 features three address inputs, allowing users to multidrop up to eight DS1721 devices on one bus.The DS1721 offers thermostatic functionality with over-temperature (TH) and under-temperature (TL) user-programmable trip-points stored in on-chip SRAM. The two trip-points provide programmable thermostat hysteresis: the thermostat output is asserted when the measured temperature exceeds THand it remains active until the temperature falls below TL.The DS1721 is available in 150mil 8-pin SO (DS1721S) and 8-pin µMAX/µSOP (DS1721U) packages. For applications requiring higher precision, theDS1631provides ±0.5°C accuracy and is functionally compatible with the DS1721.ApplicationsAlarm SystemsFibre ChannelInstrumentationNetworking