Gigabyte P67A-UD4 Motherboard

Voltage Regulator

One of the highlights of this motherboard is its voltage regulator circuit that, instead of using three regular MOSFET transistors (“high side,” “low side” and “driver”) on each phase, it uses one integrated circuit with these three MOSFETs embedded (SiC769CD, in the case of this motherboard). This approach is also known as DrMOS and allows a higher switching frequency (1 MHz instead of 250 kHz), which improves efficiency. The CPU voltage regulator circuit is controlled by an Intersil ISL6366 controller. It is interesting to note, however, that the CPU main voltage (Vcc) phases use these integrated circuits, but the CPU memory controller (VTT) phases uses low-RDS(on) MOSFET transistors (translation: higher efficiency than regular MOSFETs).

The CPU voltage regulator circuit of the P67A-UD4 has 14 phases, 12 for the CPU main voltage (Vcc a.k.a. Vcore), and two for the CPU VTT voltage (integrated memory controller and L3 memory cache). Therefore it uses a “12+2” configuration.

You have to keep in mind that you can’t compare directly motherboards with a switch speed of 250 kHz with phases that switch at 1 MHz, because the higher the switching speed the higher efficiency is.

Figure 9: Voltage regulator circuit

Figure 10: Voltage regulator circuit

Let’s not forget the other voltages used on the motherboard. The Gigabyte P67A-UD4 uses a two-phase voltage regulator for the memory voltage and a two-phase regulator for the chipset voltage, using two regular MOSFET transistors per phase (the driver MOSFET is integrated in the Intersil ISL6322 chip that is used to control these phases).

All electrolytic capacitors used on this motherboard are solid and Japanese, and the board uses only ferrite-core coils, which present less energy loss than iron-core coils (i.e., they improve efficiency).

If you want to learn more about the voltage regulator circuit, please read our tutorial on the subject.

Continuing Gigabyte’s tradition, the P67A-UD4 uses thicker copper tracks on the printed circuit board VCC and GND tracks. Usually the printed circuit board power tracks are 35 µm thick, but on the P67A-UD4 the power tracks are 70 µm thick. This feature is also called “2 oz. copper tracks” by the manufacturer.

A series of six LEDs show which phases are currently active (one LED represents two phases).

Figure 11: Active phases LEDs