PWM controller improves transient response, reduces output capacitors

Intersil introduces a new family of four-phase synchronous PWM (pulse width modulation) buck controllers. These devices achieve the fastest transient response with the fewest output capacitors and provide the industry's most integrated and cost-efficient computing power management solution.

The ISL6312, ISL6312A and ISL6322 provide a complete, 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. This family features programmable VID (voltage identification) codes for Intel and AMD DAC (digital-to-analog converter) tables.

These 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 over competitive designs. APP and APA are pulse width and positioning modulation techniques that speed up load transient response and reduce the need for external bulk output capacitors required to supply stored energy to the CPU during abrupt changes in line voltage and load current.

All three devices incorporate a unity gain differential amplifier for remote voltage sensing that compensates for differences between remote and local grounds. The ISL6312/12A/22 also integrate three MOSFET (metal oxide semiconductor field effect transistor) drivers and a PWM output for a fourth external MOSFET driver. This configuration provides the industry's most integrated and cost-efficient power management solution for desktops, workstations, servers, industrial PC motherboards, routers, switches and voltage regulator modules.

“Intersil's new PWM controllers deliver the industry's highest performance/price ratio for four-phase CPU core regulators. Intel VR10/11 and AMD AM2 CPU core solutions using Intersil's advanced controllers meet specs with substantially fewer bulk output capacitors than competitive offerings,” said George Lakkas, senior product marketing manager for Intersil's Computing Power products group. “Additionally, Intersil offers family variations for many popular computing applications. For example, the ISL6312A enables customers to monitor the CPU load current in real-time for improved reliability, while the ISL6322 is optimized specifically to work with overclocking applications such as performance motherboards using Intel's Core 2 Extreme processor.”

The ISL6312, ISL6312A and ISL6322 provide advanced control loop features to optimize transient response to load-apply and removal functions. These include highly accurate and fully differential continuous DCR (DC resistance) current sensing for load line programming and channel current balance. These features also ensure individual channel current and average overcurrent protection (OCP). These devices incorporate key features developed by Intersil specifically for these applications, including active pulse positioning modulation, enabling rapid initial response to high slew rate (di/dt) load transients. The ISL6312/12A/22 also include adaptive phase alignment that enables the fastest possible load transient response with capacitor elimination when there is a severe load turn-on.

The ISL6312A incorporates an added IOUT pin to the basic ISL6312 architecture for output current measurement. The ISL6322 provides an I2C bus input for adjusting four basic regulator functions, such as the output voltage, overvoltage protection (OVP) level, operating frequency per phase, and MOSFET driver adaptive dead time control. This family features sophisticated overvoltage, undervoltage, and overcurrent protection. Additionally, the ISL6312/12A/22 include open circuit protection on the remote sensing inputs.

Key Features
Integrated MOSFETs that save cost and board space
All-in-one VID for simplified design of Intel and AMD processors
Industry's fastest load transient response
Adaptive phase alignment for fast load transient response to severe load turn-on
Active pulse positioning for fast response to high slew rate load transients
Industry's highest system accuracy over life, line, load and temperature
Fully differential inductor DCR current sensing for individual channel and average overcurrent protection

Desktops, workstations, servers
Single board motherboards
Industrial PC motherboards
Routers and switches
Voltage regulator modules

The ISL6312, ISL6312A, and ISL6322 are available now in space-saving, 48-lead, 7 x 7 QFN packages with prices beginning at $6.67 each and ranging to $7.42 each in 1,000-piece quantities.

More information is available at:,1477,ISL6312,0.html,,1477,ISL6312A,00.html,1477,ISL6322,00.html.

To learn more, visit Intersil's Power Management page at

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