AS1908C20-T

The AS1908C20-T is a microprocessor supervisory circuit that provide the necessary reset control and system power sequencing features found in many processor-based systems. Powered by a 3.3V supply voltage, this highly integrated, single-chip device monitors system activity, issues reset signals when conditions are out of specification and facilitates proper system power-up sequencing. It is designed to provide precision reset control and system power sequencing for both complex embedded network processor applications as well as traditional 3V microprocessor-based applications. The AS1908C20-T is ideal for applications such as microprocessor based controllers, routers and switches, digital signal processing (DSP) systems, 3V embedded systems, automotive power control and safety systems, digital audio systems, and a variety of other applications.

The AS1908C20-T offers many features that help create a stable, reliable system that can easily accommodate changes in system requirements. It includes a precision reset circuit to monitor processor activity, as well as dynamic power-on reset (POR) and controller reset (CR) outputs. The reset threshold voltage is adjustable, allowing the reset response to be tuned to the system\'s speed requirements, and the reset time-out is programmable to guarantee that the reset output signals remain valid. The AS1908C20-T also provides a power-on reset time-out circuit with fault detection and lockout that produces a reset pulse when an overvoltage is detected. A flexible watchdog timer ensures system recovery from software errors.

The AS1908C20-T utilizes an integrated I2C/SMBus interface and address latch to enable programming of multiple devices on the same serial bus. The flexible power sequencing control circuit includes referenced threshold detectors and word-level enable registers for sequencing complex power-on/off applications. An integrated output driver provides quick response to the power-on reset (POR) and controller reset (CR) signals.

The AS1908C20-T provides three separate voltage monitors, one for the core voltage, one for the chipset voltage, and one for the system voltage. The voltage level of each monitor is programmable and the trip points can be adjusted to match the requirements of the system. Each monitor includes adjustable window comparators, a resetters, and power supply Undervoltage Lock-out (UVLO) logic. The AS1908C20-T can also be used to provide overvoltage (OV) protection.

The AS1908C20-T permits system designers to tailor processor reset response, reset pulse duration, POR timing, and system supervision to the needs of the application. Support for temperature monitoring further enhances system robustness. Accurate power-on detect and reset signals, dynamic voltage monitoring and power sequencing, combined with advanced features like flexible output drivers, adjustable reset threshold and timeout, I2C/SMBus programming and support for temperature monitoring, make the AS1908C20-T an essential element of any system that requires integrated processor reset and power sequencing control.

In short, the AS1908C20-T is a complete microprocessor supervisory circuit that provides the necessary reset control and system power sequencing features found in many processor-based systems. It has adjustable reset threshold and time-outs, power supply UVLO and OV detection, system voltage and temperature monitoring, and support for I2C/SMBus programming. This makes it ideal for a number of applications, including microprocessor-based controllers, embedded systems, automotive safety systems, and digital audio systems.