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Digital power supply and analog power supply

Time:2022-10-13 Views:1711
    The digital power supply is different from the common analog power supply. The former uses digital PWM, a smaller integrated digital MOSFET and DRIVER chip, and a smaller digital drain sensor, with multiple MLCCs; The analog power supply is different. Traditional PWM chips are used. Each phase is equipped with 2-4 large MOSFETs. Each phase is equipped with an independent inductor, and a capacitor with large capacity is also used. So from the appearance, we can easily distinguish between digital power supply and analog power supply.
    It can be seen that this video card of Yingchi adopts digital PWM VT1165MF, which is very small in size, integrated with MOSFET and DRIVER, CSP packaged VT1195SF MULTIPHASE power supply chip of VOLTERRA company, and CPL-4-50 digital exhaust sensor and MLCC. Obviously, this is a typical digital power supply. However, the significance of digital power supply lies not only in "volume", but also in performance.

PWM IC for digital power supply
    The PWM chip used in the video card is VT1165MF, which is very common on NVIDIA flagship video card. It can easily handle the top video card with hundreds of watts of power consumption. The conversion efficiency of the digital power supply composed of VT1165MF is far higher than that of the analog power supply, which is generally maintained at 70-80%, and reaches 90%. Not only that, the digital power supply composed of VT1165MF is more accurate, with the GPU voltage peak amplitude of only 140mV, while the analog power supply GPU voltage peak amplitude of only 300mV. The more accurate power supply is conducive to ensuring the stable operation of the GPU. Overfrequency is also easier to reach the limit, and the service life is longer.

MOSFET for digital power supply
    We have already mentioned one of the most obvious features of digital power supply and analog power supply, that is, MOSFET and DRIVER. This digital power supply video card uses VT1195SF and integrates MOSFET and DRIVER internally. Compared with the MOSFET with the operating frequency of 300KHz commonly used for analog power supply, the digital power supply MOSFET has a very high operating frequency, reaching 800KHz. The higher switching frequency makes the digital power supply transient performance better, the power consumption lower, and the conversion efficiency higher. At the same time, the current that can be driven by digital power supply can reach 40A per phase, which is far beyond the limit of 30A for analog power supply. Combined with the 4-phase digital power supply design of this video card, it can provide a current of up to 160A, which is more suitable for overclocking.
    Not only that, digital powered MOSFETs can withstand higher temperatures and adapt to a more aggressive working environment. Although MOSFETs used for general analog power supply are designed independently and have better heat dissipation, the maximum temperature they can withstand is only about 100 ℃. The digital MOSFET above can withstand up to 200 ℃. As a result, digital power supply has a wider range of applications. Regardless of cost, digital MOSFET devices have a brighter future.

Discharge inductance used in digital power supply
     Digital discharge inductance is also a very obvious feature of digital power supply. Common analog power supply uses a single packaged inductor, which has a large volume and occupies a large PCB area. The digital power supply discharge inductance CPL-4-50 used in this video card is a little like multiple inductors "integrated" together, which is smaller in size. Not only that, the exhaust inductance used in digital power supply is also better in performance. Taking the working frequency as an example, the working frequency of the inductor used in ordinary analog power supply is generally 300KHz, while the working frequency of the digital drain inductor can reach 1MHz. In addition, the internal resistance of the digital drain inductor is lower, so that the thermal loss caused by the inductor is smaller, and the conversion efficiency of the digital power supply is higher.

Finally, let‘s summarize the characteristics of digital power supply:
    1. Small size, digital MOSFET, DRIVER CSP package, small size, small digital drain volume, and smaller PCB area.
    2. The power supply is more accurate. The peak voltage of the digital power supply GPU is only 140mV, and the peak voltage of the analog power supply GPU is 300 mV
    3. The conversion efficiency of digital power supply is higher. The conversion efficiency of analog power supply is generally 70-80%, and that of digital power supply is about 90%.
    4. The digital power supply current is larger, and the limit of each phase of analog power supply is usually 30A, while the limit of each phase of digital power supply can reach 40A
    5. Digital power supply is more resistant to high temperature. The upper limit of the operating temperature of CSP encapsulated MOSFET is 200 degrees, while the upper limit of the operating temperature of the MOSFET used for analog power supply is about 100 degrees.
   6. The working frequency of digital power supply is higher, and the working frequency of digital power supply MOSFET is up to 800KHz, while the working frequency of analog power supply MOSFET is only 300KHz; The working frequency of digital power supply inductance is up to 1MHz, and the working frequency of inductance commonly used in analog power supply is only 300KHz





   





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