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Digital power supply has shown considerable advantages, but there are still some shortcomings to overcome. For example, analog control responds instantaneously to signal conditions, and digital power requires a sample, quantize, and process to feed back changes in load, so that its response to load changes is not as fast as analog power. Digital power supply footprint is greater than the analog power supply, accuracy and efficiency is slightly worse than the analog power supply. Although the advantages of the digital control approach are evident in the point-of-load (POL) system, the analog power supply is still robust in terms of resolution, bandwidth, voltage compatibility with power components, power consumption, switching frequency and cost Take advantage of. However, taking into account the advantages of digital power solutions, the use of analog circuits to build circuits with similar functions, the cost is not necessarily lower than the digital power supply.
The technology included in digital power is undoubtedly complex, but its use is not necessarily complicated. However, it requires designers have a certain programming ability, and the current power supply designers are generally based on analog design, the lack of programming training. This promotion of digital power has also caused some obstacles.
Digital power, A / D converter speed and accuracy is inversely proportional. In order to ensure that the switching power supply has higher regulation accuracy, A / D converter must have a relatively high-precision sampling, but high-precision sampling frequency requires longer A / D conversion time, as part of the feedback loop, A / D conversion time is bound to cause additional phase delay time. In addition to the phase delay associated with analog control, the latency of the conversion process inevitably results in additional wait cycles, resulting in poor real-time response of the loop. Just as the analog chip uses PI compensation with RC compensation, introducing PI regulation in the control loop to improve the real-time response of the control loop requires a larger system resource for the digital chip because digital control and analog Different control, the signal sampling is not continuous, but the rules are discrete, there will be a time interval between two samples, the value of this time is not available. In order to achieve accurate control, the time interval between samples should not be too long, that is, the sampling frequency should not be too low. As a digital chip, the result of each AD conversion is sent to the system's central processing unit, which is then used by the processor to manipulate the sampled values ​​and adjust the PI. When the sampling frequency is relatively high, this method consumes a considerable amount of system computing resources, so the performance requirements of digital chips are relatively high. Dedicated to the power control of the digital chip is not much, although in the case of relatively high demand will generally use the DSP chip, the operation and sampling speed, powerful, but the price is more expensive. And general-purpose DSP chip is not dedicated as a power control chip to use, the general power application of its chip resource utilization is not high, under certain conditions, the use of DSP chip as the core of power digital control is a waste.
Therefore, cost is clearly a constraint on the widespread use of digital power. Because the cost of digital implementations appears to be higher than similar analog implementations and there are concerns about the adoption of digital power products, it is only from the user's perspective that when the cost of a digital power supply is equal to or lower than the analog power supply Because the cost is the first market factor that the Chinese market considers), can offer the many advanced functions that the analog power supply can not at the same time, digital power will be considered.
There is also a concern about digital power is that it is not as tested as analog power supply after years of use, so reliability is not high. But just as digital circuits are conceptually better than analog circuits, reliability is a design issue, not a digital one.
In summary, analog power products are more advantageous in applications that are simple to use and with few parameter changes because their application can be targeted by hardware curing. In the more controllable factors, the need for faster real-time response, you need to manage multiple power supplies, complex high-performance system applications, digital power is an advantage.