Power Management

What is the role of a PMIC (power management IC) used in smartphones and similar devices?

  1. AGenerating the multiple voltages the SoC, memory and peripherals need from the battery and managing power-up sequencing and voltage changes
  2. BGenerating images for the display
  3. CTransmitting and receiving radio signals
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Answer: A. Generating the multiple voltages the SoC, memory and peripherals need from the battery and managing power-up sequencing and voltage changes

SoC cores, memory, I/O, cameras and sensors each need different voltages. A PMIC integrates many switching regulators and LDOs, efficiently generating the required voltages from the battery and, as directed by the SoC, changing voltages for DVFS, switching power to blocks on and off and powering up in the required order. Some also manage battery charging and fuel gauging.

  • A. Correct. Some also manage battery charging.
  • B. Images come from the GPU and similar.
  • C. Radio is handled by RF components.
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More Power Management questions

  1. In chips using multiple supply voltages, why must the power-up order (power sequencing) be observed?
  2. What characterizes near-threshold operation, running with supply voltage lowered close to the transistor threshold?
  3. As supply voltage is lowered, total energy per operation reaches a minimum at some voltage and then rises if voltage is lowered further. Why?
  4. A 50 W CPU is fitted with a cooler of thermal resistance 0.5 K/W. Roughly how many degrees above ambient does the chip run (ignoring other heat paths)?
  5. Why are temperature sensors often placed at many locations within a large chip?