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Renesas unveils 'first' reset IC for MCUs

Posted: 03 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Renesas? RNA50C27AUS? reset IC? Embedded Systems Conference? ESC-Taiwan?

Renesas Technology America Inc. has announced the RNA50C27AUS, said to be the industry's first reset IC that incorporates a core power-on control function for microcontrollers that operate core logic circuits from a 1.8V power supply and I/O peripheral circuits from a 3.3V supply.

According to the company, the new reset IC eliminates the complicated power-on timing aspect of power-supply system design needed to prevent these dual-power-supply microcontrollers from going into a runaway (fault) condition. It simplifies the electronics by eliminating the external transistor switch and timing circuit that would be necessary if a traditional reset IC was used. Also, the device helps ensure reliable system operation by monitoring both supply voltages and generating a reset if either one falls below a critical level. It eases system design by providing a control function for turning the core power supply on or off, Renesas said.

To ensure proper operation, the 1.8V and 3.3V supplies of dual-power-supply microcontrollers must be turned on in the proper sequencefirst the 1.8V supply, then the 3.3V supplyand then only when those supply voltages are above critical thresholds. Further, after a system reset is initiated, the release time of that signal must be at least a certain minimum length, a time delay that is determined by the application. The new reset IC promises all these capabilities and more.

The device's external resistor and capacitor determine the reset signal release time. The reset output signal has 10ns rise and fall times. To accommodate different applications, an open-drain output or CMOS output can be selected for the reset output signal. Using the CMOS output allows a direct connection to a microcontroller's reset pin.

The precision with which the dual-voltage reset IC detects abnormalities in the voltages of the core and I/O power supplies is 1 percent maximumthe same degree of precision provided by conventional reset ICs. Package for the RNA50C27AUS is an 8-pin SSOP-8 with dimensions of 2.2-by-2.4mm (excluding pins), and Pb-free specifications.

The RNA50C27AUS is currently available for 70 cents.

Renesas will exhibit its line of semiconductor system solutions for mobile, automotive and PC/AV markets at the 6th Annual Embedded Systems Conference-Taiwan on August 17-18 at the Taipei International Convention Center.

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