The STM690A/692A/703/704/802/805/817/818/819 supervisors are self-contained devices which provide microprocessor supervisory functions with the ability to non-volatize and write-protect external LPSRAM. A precision voltage reference and comparator monitors the VCC input for an out-of-tolerance condition. When an invalid VCC condition occurs, the reset output (RST) is forced low (or high in the case of RST). These devices also offer a watchdog timer (except for STM703/704/819) as well as a power-fail comparator (except for STM818) to provide the system with an early warning of impending power failure.
These devices are available in a standard 8-pin SOIC package or a space-saving 8-pin TSSOP package.
■ 5 V operating voltage
■ NVRAM supervisor for external LPSRAM
■ Chip-enable gating (STM818 only) for external LPSRAM (7 ns max prop delay)
■ RST and RST outputs
■ 200 ms (typ) trec
■ Watchdog timer - 1.6 sec (typ)
■ Automatic battery switchover
■ Low battery supply current - 0.4 µA (typ)
■ Power-fail comparator (PFI/PFO)
■ Low supply current - 40 µA (typ)
■ Guaranteed RST (RST) assertion down to VCC = 1.0 V
■ Operating temperature: –40 °C to +85 °C (industrial grade)
■ RoHS compliance
– Lead-free components are compliant with the RoHS directive