Bigger better bucks

Sept. 13, 2006
PWM control and regulation developments provide improved performance in transient response and power density

PWM control and regulation developments hit the news with claims of improved performance in transient response and power density. Take the new family of four-phase synchronous PWM (pulse-width modulation) buck controllers crafted by Intersil. According to the company, the devices deliver the highest performance/price ratio for four-phase CPU core regulators. Intersil says Intel VR10/11 and AMD AM2 CPU core solutions using these controllers meet specs with substantially fewer bulk output capacitors than competitive offerings.

The ISL6312, ISL6312A, and ISL6322 provide an integrated, precision voltage-regulation system for advanced Intel VR10/11(Intel Core 2 Duo and Intel Core 2 Extreme) and AMD AM2 5/6-bit microprocessors. The family features programmable VID (voltage identification) codes for Intel and AMD DAC tables.

Family variations are available for many popular computing applications. For example, the ISL6312A lets customers monitor the CPU load current in real-time for improved reliability. And the ISL6322 is optimised specifically to work with overclocking applications such as performance motherboards using Intel's Core 2 Extreme processor.

The devices use Intersil's proprietary active-pulse-positioning (APP) and adaptive-phase-alignment (APA) modulation schemes to achieve the industry's fastest transient response with the fewest output capacitors compared with competitive designs. APP and APA are pulse-width and positioning modulation techniques. All three devices incorporate a unity-gain differential amplifier for remote voltage sensing that compensates for differences between remote and local grounds.

Next up is National Semiconductor with its new family of buck regulators, which it claims has the industry's highest power density in ultra-small packaging. The first products in this new family of monolithic PWM converters offer good power density due to their high level of integration, high-frequency operation, and ultra-small packaging.

The LM2831, in a tiny SOT23-5, provides a 1.5A output current while operating at 1.6 or 3MHz. It also comes in a 6-lead LLP(r) package. The 2A LM2832, in a 6-lead LLP package, is available at 550kHz, 1.6MHz, and 3MHz switching frequencies. It is also available in an 8pin MSOP. The 1A LM2830 offers 1.6 and 3MHz switching frequency options in SOT23-5 and 6-lead LLP packages.

The regulators are monolithic, high-frequency, PWM, step-down external components. Their switching frequencies are set internally at 550kHz, 1.6MHz, or 3MHz.

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