SoC It to Me! Supercharge with PMIC

Abstract

As embedded systems grow increasingly complex, traditional microcontrollers often fall short of meeting modern performance demands. This shift has led many designers to adopt system on a chip (SoC) solutions, which offer greater integration and processing power—but also introduce new challenges, particularly in power management. This article will explore the foundational considerations for powering an SoC, focusing on how to interpret and apply key information from data sheets and technical reference manuals. A walk through of five critical conditions that influence power scheme design provides a practical, step-by-step guide to help engineers confidently integrate power management ICs (PMICs) into their SoC-based systems.

Introduction

As embedded systems evolve to handle more demanding applications—ranging from edge AI to advanced connectivity and multimedia processing—designers are increasingly turning to system on a chip (SoC) solutions. These highly integrated devices offer significant performance and functionality advantages over traditional microcontrollers, but they also introduce new design complexities, particularly in the realm of power management.

Unlike simpler microcontrollers that often require a single supply voltage, SoCs typically demand multiple power rails, each with specific voltage levels, current capabilities, sequencing requirements, and timing constraints. Failing to meet these requirements can lead to unreliable operation, reduced performance, or even permanent damage to the device.

What Is an SoC?

An SoC is an integrated circuit that consolidates all the essential components of a computer or electronic system onto a single chip. This includes the central processing unit (CPU), graphics processing unit (GPU), memory controllers, input/output (I/O) interfaces, and often specialized modules like those used for digital signal processing (DSP), AI accelerators, and wireless communication units (Wi-Fi, Bluetooth®, LTE/5G). The goal of an SoC is to deliver high performance and functionality in a compact, power-efficient form factor, making it ideal for mobile and embedded applications.

The development of SoCs began in the late 1980s and early 1990s, driven by the need for smaller, more efficient electronics. Early SoCs were used in embedded systems and mobile phones, but as semiconductor technology advanced, SoCs became more powerful and versatile. Today, they are the backbone of modern consumer electronics, powering everything from smartphones and tablets to smartwatches, medical devices, smart TVs, automotive systems, and Internet of Things (IoT) devices.

SoCs are crucial in today’s technology landscape because they enable high levels of integration and performance while minimizing power consumption and physical space. This is particularly important in portable and wearable devices, where battery life and compact design are critical. Their integration also reduces the number of components on a circuit board, which simplifies design, lowers manufacturing costs, and improves reliability.

Key features of SoCs include high integration, energy efficiency, real-time processing capabilities, and support for advanced connectivity. Their advantages are numerous, offering faster processing speeds, lower power consumption, reduced system size, and cost-effectiveness. Additionally, many SoCs are designed with specific applications in mind, allowing for customization and optimization that further enhances performance and efficiency.

What Is a PMIC?

A power management integrated circuit (PMIC) is a highly specialized semiconductor device designed to manage and regulate the power requirements of modern electronic systems. These circuits are essential in complex devices such as smartphones, tablets, laptops, wearables, and embedded systems where multiple components require different voltage and current levels to operate efficiently and reliably. The PMIC acts as the central hub for power distribution, ensuring that each subsystem receives the correct amount of power at the right time, while also optimizing energy usage to extend battery life and reduce heat generation.

PMICs typically integrate several key functions into a single chip, including voltage regulation (via buck, boost, or low dropout (LDO) regulators), battery charging and monitoring, power sequencing, thermal management, and fault protection. This level of integration not only saves space on the circuit board but also simplifies design and improves overall system reliability.

The concept of integrated power management began to gain traction in the late 1980s and early 1990s, as portable electronics like early mobile phones and laptops became more widespread. Initially, power management was handled by discrete components, which were bulky and less efficient. As semiconductor technology advanced, manufacturers began to integrate these functions into single chips, giving rise to the first generation of PMICs. Over time, PMICs evolved to support increasingly sophisticated power architectures, including dynamic voltage scaling and intelligent power gating, which are now standard in energy-conscious designs.

Today, PMICs are a cornerstone of modern electronics, enabling devices to operate longer on smaller batteries, manage thermal loads more effectively, and meet stringent energy efficiency standards. They are especially critical in battery-powered and space-constrained applications, where every milliwatt and millimeter counts.

A discrete power management solution involves using individual components—such as separate buck converters, LDOs, battery chargers, and protection circuits—each performing a specific function. While this approach offers flexibility in selecting components tailored to exact specifications, it often results in a larger PCB footprint, increased design complexity, and more challenging thermal and electromagnetic interference (EMI) management. In contrast, a PMIC integrates multiple power functions into a single chip, significantly reducing board space, simplifying the design process, and improving overall system efficiency. Figure 1 illustrates the contrast between traditional discrete power management and a PMIC-based solution, highlighting the benefits of integration. PMICs are especially advantageous in space-constrained applications like wearables, where compactness, low power consumption, and streamlined power sequencing are critical. Additionally, PMICs often include advanced features such as power monitoring, fault protection, and communication interfaces, which would require additional circuitry in a discrete setup. Overall, while discrete solutions may be suitable for highly customized or high power systems, PMICs offer a more efficient and reliable approach for modern, compact electronic designs.

A PMIC is typically connected to an SoC through a combination of power and communication interfaces to ensure efficient and coordinated power delivery. The PMIC supplies the various voltage rails required by the SoC, such as core voltage, I/O voltage, and memory voltage, using integrated regulators like buck converters and LDOs. These power rails are connected directly to the corresponding power input pins on the SoC. In addition to power delivery, the PMIC often communicates with the SoC via a digital interface such as I²C or SPI. This communication allows the SoC to control and monitor the PMIC’s functions, including enabling or disabling power rails, adjusting output voltages, reading fault or status registers, and managing power sequencing during startup and shutdown. Figure 2 shows a typical connection diagram of a PMIC interfacing with an SoC, illustrating both the power and communication pathways. This tight integration ensures that the SoC operates reliably and efficiently, especially in power-sensitive applications like mobile and wearable devices.

Key Parameters to Consider When Powering an SoC with a PMIC

When integrating a PMIC to power an SoC, several critical parameters must be carefully evaluated to ensure reliable and efficient operation. These parameters are typically derived from the SoC’s data sheet or technical reference manual, which outlines the electrical and functional requirements of the chip. Understanding these parameters is essential for designing a robust power delivery architecture.

• Voltage requirements: Understanding the core, I/O, and peripheral power domains.
• Current demands: Estimating peak and average current consumption for each rail.
• Power sequencing: Determining the correct order of powerup and power-down events.
• Timing constraints: Managing delays and ramp times between power rails.
• Power modes and transitions: Supporting dynamic power states for energy efficiency.

By the end of this guide, a designer will have a clear, practical framework for designing a power architecture that ensures the SoC performs reliably and efficiently. Whether new to SoC design or refining an existing approach, this walkthrough provides the confidence to navigate the power-up path.

Typical Voltage Requirements

Every SoC has multiple power domains—such as core logic, I/O interfaces, analog blocks, and memory—that often require different voltage levels. These voltages are typically specified in a data sheet under sections like “Recommended Operating Conditions” or “Power Supply Requirements.”

• Core voltage (VDDCORE): Powers the CPU and internal logic. Often the lowest voltage (for example, 0.8 V to 1.2 V).
• I/O voltage (VDDIO): Powers the input/output interfaces. Common values include 1.8 V, 2.5 V, or 3.3 V.
• Analog voltage (VDDA): Powers analog peripherals like ADCs or PLLs. Requires low noise and stable supply.

PMIC tip selection: Use LDOs or buck converters to generate these voltages efficiently.

Current Demands

Each power rail must supply enough current to meet both average and peak demands. These values are often found in the “Electrical Characteristics” section or estimated using power modeling tools provided by the SoC vendor.

• Peak current: Needed during boot-up or high performance modes.
• Average current: Helps size power supplies and manage thermal design.

PMIC tip selection: Always add a safety margin (for example, 20% to 30%) to your current estimates to account for transient loads and future scalability.

Power Sequencing

Many SoCs require power rails to be turned on and off in a specific order to avoid latch-up, brownouts, or damage. This sequence is usually documented in the “Power-Up/Down Sequence” section of a data sheet.

• Typical order: Core voltage > Analog voltage > I/O voltage
• Dependencies: Some peripherals or memory interfaces may require synchronized power-up.

PMIC tip selection: Use PMICs with built-in sequencing or discrete power sequencers to automate this process.

Timing Constraints

In addition to sequencing, timing between rails matters. This includes:

• Ramp time: How quickly a voltage reaches its target level.
• Delay time: Minimum wait time between enabling different rails.
• Hold time: Duration a rail must remain stable before the next stage begins.

PMIC tip selection: Check for timing diagrams in the data sheet and use programmable PMICs or microcontroller GPIOs to fine-tune delays.

Power Modes and Transitions

Modern SoCs support multiple power modes (for example, active, idle, sleep, deep sleep) to optimize energy efficiency. Each mode may require different voltage levels or enable/disable certain rails.

• Dynamic voltage scaling (DVS): Adjusts core voltage based on workload.
• Power gating: Turns off unused blocks to save power.

PMIC tip selection: Choose PMICs that support dynamic control via I2C/SPI or GPIOs to enable smooth transitions between power states.

Where Are PMICs Used and What Is the Importance?

PMICS are found in most smartphones, tablets, and wearable devices. They are also in laptops and ultrabooks, automotive electronics, IoT devices, industrial, and medical equipment.

When it comes to smartphone and tablet applications, the PMIC plays a central role in ensuring efficient, safe, and intelligent power distribution across the entire device. These mobile devices are highly integrated systems with multiple subsystems—such as the CPU, GPU, memory, display, camera, wireless radios (Wi-Fi, Bluetooth, cellular), sensors, and storage—all of which have different power requirements. The PMIC is responsible for managing these diverse needs in real time.

A Closer Look at the Role of PMICs in Modern Medical Equipment

PMICs in medical equipment are responsible for regulating multiple voltage rails, managing battery charging and backup systems, and ensuring uninterrupted operation during power transitions or failures. For example, in portable or wearable medical devices like glucose monitors or portable ECGs, the PMIC manages power from rechargeable batteries, optimizes energy consumption to extend battery life, and ensures that the device can operate safely even under low power conditions.

In more complex systems such as ultrasound machines, patient monitors, or MRI scanners, PMICs are integrated into the main control boards and are tasked with delivering precise voltages to analog front ends, digital processors, memory, and communication modules. These systems often require power sequencing, where different subsystems must be powered on or off in a specific order to prevent malfunction or data loss. The PMIC handles this sequencing automatically, based on programmable logic or control signals from the system’s microcontroller or processor.

Additionally, PMICs in medical applications often include redundant safety features such as overvoltage protection (OVP), undervoltage lockout (UVLO), overcurrent protection (OCP), and thermal shutdown. These features are essential to prevent damage to sensitive electronics and to ensure patient safety. In implantable or wearable devices, PMICs are designed with ultra low power consumption and may include energy harvesting interfaces to support wireless charging or power from body heat or motion.

Integration-wise, PMICs are typically mounted on the main PCB of the medical device and are often custom-selected or even custom-designed to meet the specific power profiles and regulatory standards (like IEC 60601) required in medical environments. Their compact size and high level of integration help reduce board space and improve system reliability—both crucial in medical design.

Key Advantages of PMIC

• Efficiency: PMICs optimize power conversion and distribution, reducing energy loss and heat generation. This is especially critical in battery-powered devices where maximizing battery life is a top priority.
• Integration: By combining multiple power functions—such as voltage regulation, battery charging, and power sequencing—into a single chip, PMICs reduce the need for discrete components. This saves board space, simplifies design, and lowers overall system cost.
• Reliability: PMICs include built-in protection features like OVP, OCP, and thermal shutdown. These safeguards enhance the durability and safety of the device, which is particularly important in mission-critical applications like medical and automotive systems.
• Customization: Many PMICs are configurable or even custom-designed to match the specific power requirements of a system. This allows for fine-tuned performance, better thermal management, and seamless integration with the main processor or SoC.

Other Features of PMICS

Some PMICS are equipped with battery management, which handles charging, discharging, battery health monitoring, and protection. Very low power consumption during sleep mode and low power modes that will help reduce power consumption when the system is idle or in standby mode.

In the rapidly evolving world of wearable technology, power efficiency, compact design, and feature integration are critical to delivering a seamless user experience. Analog Devices addresses these challenges with a diverse portfolio of highly integrated PMICs, each engineered to meet the unique demands of wearable devices.

Whether developing a smartwatch, a health monitoring device, or a fitness tracker, these PMIC solutions strike the perfect balance between integration, efficiency, and performance. These PMICs are designed to minimize board space, extend battery life, and simplify system design—key factors in the success of any wearable product. See Table 1.

Conclusion

Powering an SoC is far more than just supplying voltage—it’s a carefully orchestrated process that directly impacts system stability, performance, and efficiency. As SoCs continue to replace simpler microcontrollers in advanced applications, understanding their power requirements becomes essential for every embedded designer.

By starting with the SoC’s data sheet and focusing on five key conditions—voltage requirements, current demands, power sequencing, timing constraints, and power modes—one can build a power architecture that not only meets technical specifications but also supports long-term reliability and scalability. Integrating a PMIC into the design can simplify this process, offering features like programmable sequencing, dynamic voltage scaling, and fault protection in a compact footprint.

Whether designing for wearables, industrial automation, or edge computing, mastering these power fundamentals will provide the confidence to tackle even the most complex SoC-based systems. So, power up smartly—and let your design shine.

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