PowerNow! technology aims to reduce energy consumption. Microprocessors utilizing this technology are focused on embedded applications and have been designated AMD-K6- 2E+. Since power consumption plays a very important role for these applications, passive heat dissipation must be used effectively, for which it is important to minimize power consumption as much as possible so that a fan is not necessary.
The improved version of the original technology first appeared for AMD Athlon 4Mobile Athlon XP-M and Duron mobile processors.
PowerNow! technology allows microprocessors to actively operate at less than 3 watts of power without compromising performance.
Key Features of PowerNow! technology:
- up to 32 allowable core voltage levels, the full operating frequency range of 0.925 to 2.00 V in 25 or 50 mV steps is supported; the voltage step: 25 and 50 mV is shallower than that adopted in IntelP6;
- frequency control - from a minimum of 133 (or 200 MHz) in 33 or 50 MHz increments;
- voltage and frequency are set independently;
- automatic mode support for precise and error-free power and performance adjustment.
In high performance mode, the processor operates at the maximum rated voltage and speed to provide the highest possible performance.
When you switch to power saving mode, the processor adjusts to operate at a lower voltage and frequency to maintain the most efficient power consumption. This mode of operation ensures that only the required amount of energy is dissipated according to the operational requirements of the application.
These features are provided through modifications made to the processor using PowerNow! technology. These changes include built-in processor frequency control and additional outputs to control a programmable voltage regulator. None of these functions require changing any of the external bus frequencies, thus maintaining overall system integrity and reducing the risk of potential complications.
Implementing PowerNow!:
- The extended power management register (EPMR) is used for voltage control; by changing the contents of the EPMR, the operating system can change the voltage and frequency multiplier settings;
- external VI D pins can be routed to an external programmable voltage regulator to change the core voltage;
- the CPU frequency is changed by writing to a 4-byte field in the ERM that controls the bus frequency multiplier;
- these actions are performed inside the processor and do not affect any external signals or clock generators. The external BF (Bus Frequency) bus pins must be used to supply POST and RESET; the state of these pins does not change when using PowerNow! technology;
- PowerNow! technology can be used for low-power microprocessors with supply voltage of 1.4 V and clock frequencies of 200 MHz;
- by using a large number of intermediate steps between the permissible maximum and minimum parameters, the optimum performance and power for any application can be determined and set at any time.
For embedded applications, software supporting AMD PowerNow! technology can be implemented in one of two ways: for real-time operating systems like Linux, PowerNow! technology is supported by the operating system or BIOS; for Microsoft operating systems, PowerNow! is supported at the driver level.
OS or BIOS drivers make the necessary settings in the microprocessor's power control register ERM and perform the required changes. Software control makes it easy to apply PowerNow! technology.
