The STM6600 and STM6601 smart push-button on/off controller chips offer protection for battery-operated devices in many ways. These include minimizing the risk of powering up without sufficient battery energy to complete the sequence, which can damage the system. It can also prevent power-up if it detects a fault in the power supply.
The STM660x ICs also implement Smart Reset capabilities to help users recover products that have crashed or frozen during normal operation. Smart Reset requires both push-buttons to be held down for a minimum period, controlled by an external capacitor, before a reset occurs. This two-action reset eliminates the need to hide the reset button behind a hole in the outer casing to prevent accidental use, thereby lowering engineering costs and allowing the casing to be sealed if required.
The protection features integrated in the STM660x devices replace as many as 30 or 40 discrete components or a CPLD (complex programmable logic device) with a separate voltage regulator, clock and a voltage detector to determine the battery condition. Alternatively a microcontroller with dedicated housekeeping features could be used but, this too, requires an external crystal, a voltage detector and must also be programmed.
The STM660x’s 2 x 3 mm footprint occupies less than half the PCB space of any alternative approach. It also has a low active power consumption of 6 µA and a zero-power shutdown mode consuming less than 1 µA.