STMicroelectronics announces four new industry standard microprocessor Reset chips intended for high volume, cost sensitive micro-processor-based applications, including cellular and GSM phones. The Reset circuits are supervisory devices that are commonly used to monitor the microprocessor supply voltage, and to generate a reset signal if that voltage falls below tolerance.
The STM809, STM810, STM811 and STM812 devices are designed to provide precision monitoring of 3V, 3.3V and 5V supply voltages, and each is available with one of five nominal voltage thresholds, from 2.63 V to 4.63 V. They also provide Power-On Reset when system power is first applied, and two of them (STM811 and STM812) include a manual Push Button Reset input which requires no additional debounce circuitry. The small footprint SOT23 and SOT143 packages are drop-in compatible with industry standard devices, and are suitable for virtually any application that uses a microprocessor. The new devices are very cost-competitive with existing products, and ST expects to achieve significantly shorter high volume lead-times than the market average. Their push-pull outputs provide a 140 ms (min) Reset pulse after the supply has risen above the threshold; the outputs of STM809 and STM811 are active low, the outputs of STM810 and STM812 are active high. The Reset assertion is guaranteed for a supply voltage down to 1 V, and the devices offer excellent immunity to supply transients; typically, a transient extending 100 mV below the threshold for less than 20 μs will not trigger a Reset pulse. The STM809 and STM810 are 3-pin devices in SOT23-3 packages, while the 4-pin STM811 and STM812 use the SOT143-4 package. All are specified for operation over the 㫀°C to +85°C industrial temperature range.