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Controllers meet power requirements of Intel, AMD CPUs

Posted: 02 Dec 2005 ?? ?Print Version ?Bookmark and Share

Keywords:Maxim Integrated Products? MAX8809A? MAX8810A? controller? Intel?

Maxim Integrated Products released two new products it claims as the first single-chip 2-/3-/4-phase controllers with integrated dual driver, designed specifically for next-generation Intel and AMD core power requirements. According to the press release, the MAX8809A and MAX8810A controllers meet every specification for power, performance and accuracy in today's demanding CPUs.

"The MAX8809A and MAX8810A provide design engineers with a new approach to addressing high-current Intel and AMD core processor requirements," said Jonathan Horner, business manager for Maxim's non-portable products. "The combination of technology, simplicity and flexibility will definitely reduce design time, risk and total solution costs."

The MAX8809A operates as a single-chip, 2-phase solution with integrated drivers, making it a suitable stand-alone solution for power requirements up to 65W. This device easily scales to higher power requirements by including a 3rd-phase PWM output on chip, and integrates a dual driver but adds two additional PWM outputs.

In addition, a selection pin (SEL) allows the designer to program the controller to support three different processors, including Intel VRD10.1 and next-generation CPUs from both Intel and AMD. Included is support for VID codes, VID signal thresholds, proper startup sequencing and overvoltage protection (OVP) thresholds.

Low input bias current
Both the MAX8809A and MAX8810A use an extremely low input bias current (0.15A typical) differential amplifier to support remote output-voltage sensing at the processor die. This eliminates the effects of trace impedance in the output and return paths. Initial output voltage accuracy is 10.4 percent due to a high-accuracy digital-to-analog converter combined with precision current-sense amplifiers. Maxim added that the precision error amplifier ensures high voltage-positioning accuracy over the full load range.

The two new products utilizes peak current-mode control to provide fast transient response and inherent current sharing. Applications can use resistor current sensing, or take advantage of the inductor DC resistance (DCR) to save cost and improve efficiency. Well-matched current-sense amplifiers ensure that current-sharing mismatch is less than 5 percent between phases. Current-sharing accuracy is further enhanced through use of a proprietary Rapid Active Averaging scheme, which eliminates errors due to current-sense component tolerances. Additionally, current-sense information is fully temperature compensated, which results in accurate voltage positioning and current-limit operation over the full -400C to 850C operating temperature range.

Built-in protection mechanisms
Overcurrent protection is extremely robust, and current limiting is cycle-by-cycle and based on temperature-corrected average current. Both the MAX8809A and MAX8810A fold back current to 50 percent of the maximum value during an overcurrent event, reducing stress on input and output components Other built-in protection mechanisms include overtemperature protection and OVP.

Additional features of the two new devices include a wide input-supply range (up to 26V), an enable control pin, and power-good output signal. Soft-start time is externally programmable with a resistor.

The MAX8809A is available in a Pb-free, 5-by-5mm, 40-pin TQFN package, and the MAX8810A is housed in a Pb-free, 6-by-6mm, 48-pin TQFN. Pricing for the MAX8809A and MAX8810A starts at $2.40 and $2.50, respectively (1,000-up FOB USA).

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