PWM controller promises faster response

The NCP5381 is billed as the industry's first asynchronous dual-edge pulsewidth modulation controller.

New from ON Semiconductor, the NCP5381 is billed as the industry's first asynchronous dual-edge pulsewidth modulation (PWM) controller.

The new controller is ideal for applications such as Pentium IV processor motherboards, VRM modules, and graphics cards where fast transient response and advanced power management are vital.

"Using working PC motherboards, ON Semiconductor has demonstrated the VR10- and VR11-compliant performance of the dual-edge NCP5381 PWM controller", said Michael Stapleton, Director of ON Semiconductor's Analog Computing Products Group.

"Customers who have been shown the live demo have been impressed with the controller because it offers superior performance, can be integrated easily into their existing motherboard designs and ultimately assists in lowering the overall costs of their Vcore power management subsystems".

One of the key challenges facing CPU power designers is that although long-term trends include increasing current levels and faster current transitions, the voltage to the CPU on a specific motherboard must remain stable while active power demands fluctuate.

Designed to enable the power management subsystem to respond to users' activation of high-performance computing functions, the NCP5381 delivers significantly faster response to load transients than existing industry single-edge, latched, clocked or synchronous modulation products.

This allows the subsystem to operate at a lower frequency - with fewer and smaller hold-up capacitors compared with existing modulation approaches.

The result is a physically more compact solution that requires fewer external components and is, in turn, more cost-effective than existing solutions.

"Within the industry, it has been commonly believed that the next step in CPU power control - and specifically Vcore power control - would require a costly digital control system to overcome the performance limitations of today's synchronous controller architectures", said Larry Sims, Senior Vice President and General Manager of ON Semiconductor's Analog Power Group.

"With the successful introduction of our PWM controller, ON Semiconductor has demonstrated that its innovative dual-edge architecture offers a high-performance solution for advanced CPU power control that is more cost-effective than digital or other analogue platforms".

Along with the NCP5381, ON Semiconductor's CPU power control four-phase solution includes four stand-alone 12V NCP3418B MOSFET gate drivers for synchronous buck applications.

These are offered in SOIC-8 and DFN-10 Pb-free packages.

Eight 25V, single N-channel MOSFETs are also part of the dual-edge Vcore subsystem solution - four 45A NTD50N03R MOSFETs and four 65A NTD65N03R MOSFETs.

Both these devices offer low on-resistance, low gate charge and low reverse recovery charge, and are offered in Pb-free DPAKs.

One driver and two MOSFETs are used to drive each of the four output phases of the NCP5381.

NCP5381MNR2G is available in a 40-pin Pb-free QFN package.

Samples are available now, with production scheduled for the first quarter of 2006.

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