STMicro Introduces New Voltage Supervisors For Multi-Voltage Systems
STMicroelectronics (STM) introduced the STM6904/5 four- and five-channel voltage supervisors that are said to save space, cost and power, while ensuring the integrity of multi-voltage systems such as set-top boxes, telecom and networking equipment, computing and data-storage systems.
A low current draw of 12µA (typical), combined with small-outline 8-pin MSOP package, ensure minimal impact on overall system power consumption and board layout. The STM6905 offers five monitored channels and a fixed delay-to-reset time (210ms), whereas the STM6904 offers additional user-selectable reset delay times while monitoring up to four channels.
By providing more channels than earlier devices, these new ICs allow engineers to monitor more voltage rails within a given system without adding extra supervisor ICs. The ICs generate a logic-low reset signal if any of the monitored voltages falls below its threshold. A manual Reset pin is also provided, allowing designers to implement a push-button or system-controlled reset, if required.
To maximize flexibility, two channels have factory-preset thresholds, while the remaining inputs are user-configured using external resistors. The primary monitor can be factory-preset for a threshold between 2.866 and 3.078V. The second fixed threshold can be preset between 1.050 and 2.333V. The remaining inputs provide freedom for engineers to adjust the threshold voltage from 1.050 to 3.078V using a voltage-divider network.
Both devices operate from 0.8 to 5.5V across the -40 to +85°C industrial temperature range. Voltage-threshold accuracy of ±1.8% is maintained over the full temperature and voltage ranges. The reset output is valid for supply voltages down to 0.8V.
The STM6904 and STM6905 are now in full production, and samples are readily available. In quantities of 10,000, the STM6904 is priced at $0.55, and the STM6905 is priced at $0.65.
