Management application of medical power supply in various fields--Instrumentation
Examples of instrumentation applications are: blood analyzers, dialyzers, and clinical diagnostic equipment. Instrumentation equipment is usually non-portable. The requirements for power management in this type of application are not limited by many factors as discussed in the "Home Healthcare" section. In the field of instrumentation, more power can usually be obtained, so the requirements for power efficiency are not strict. Although high integration is undoubtedly helpful to the system, it is not the primary consideration. In most cases, low noise performance is important for instrumentation applications. Switching regulators and linear regulators must have extremely low noise in order to perform extremely high-precision measurements. Usually a silver box type AC-DC power supply is used to generate one or more intermediate voltages. Subsequently, these power rails are used to generate lower voltages.
Figure 3 shows a miniature PMU (power management unit). It is an ADP5050 device, powered by a 12V rail from an AC-DC power supply. The PMU integrates four switching regulators and a linear regulator. Although compact, it integrates many necessary functions. The switching frequency of a single buck regulator is synchronized and phase shifted together to minimize the noise on the input line and supports the use of small value input capacitors. A unique feature is that two switching regulators can be operated at half the switching frequency of the other two regulators. This can maintain a predictable low EMI curve, while allowing low-power rails to operate at higher switching frequencies, and use lower switching frequencies on high-power rails to achieve the highest possible efficiency.
The last very important point is to provide an I2C interface, which can dynamically change the output voltage, check the chip temperature, set the phase shift of different channels, indicate a good power supply, and enable a single channel. These functions help the intelligent instrumentation system to monitor and control the power management performance.
