Five PMICs and their quest for new features and greater integration

By Majeed Ahmad, contributing writer

Look at designs ranging from smartphones to smartwatches and from high-definition displays to dual-lens cameras, and what’s common under the hood is a power management IC (PMIC) that controls the energy supply to the host system.

The sophisticated new power architectures are now enabling ever-smaller PMIC footprints to eliminate multiple discrete components. At the same time, however, the addition of new functionalities in electronics design is resulting in a growing complexity of the PMIC fabric.

This article reviews five PMIC devices operating in prominent design areas to identify the new features and gauge higher levels of integration that they offer. A closer look at these PMICs serving multiple design areas also reveals the latest developments in programmability, power sequencing, power monitoring, and circuit protection.

1. PMIC optimized for ADAS
The new PMIC from STMicroelectronics claims to power an entire camera- or radar-based advanced driver-assistance system (ADAS). The L5965  power chip supports sensors, memory, processor, and controller area network (CAN) interface circuitry with seven regulated outputs. It also employs one-time programmable (OTP) cells for setting the output voltages.

As a result, the PMIC’s register-programmable outputs eliminate the need for voltage-setting resistors because the on-chip regulators can be used without external compensation circuitry. This sequencing also provides flexibility to configure the PMIC for a wide range of ADAS applications.

It’s worth mentioning as well that the L5965’s ability to operate directly from the vehicle battery enables its use without a pre-regulator. Furthermore, the integrated functional safety features designed in compliance with the ISO 26262 standard enable designers to fulfill Automotive Safety Integrity Level (ASIL) requirements up to ASIL-D.

2. Powering application processors
ROHM Semiconductor has optimized its PMIC for NXP’s i.MX 8M Mini family of application processors that serve multimedia designs such as voice interface and video streaming. The BD71847AMWV  power chip integrates all power rails for the processor as well as power supplies required by DDR memory and system I/O.

The BD71847AMWV integrates six DC/DC buck converters, six low-dropout (LDO) regulators, a 1.8-V/3.3-V power switch for SDXC cards, a 32-kHz crystal driver, and a buffered output clock. That allows the PMIC to feature extensive monitoring, circuit protection, and power state control logic.

ROHM’s BD71847AMWV power management chip is part of the NXP i.MX 8M Mini Evaluation Kit. (Image: ROHM Semiconductor)

ROHM’s PMIC incorporates programmability into the power control sequencer and all power rails. That, in turn, leads to flexible power control and management, buffered sleep clock, circuit protection functions, etc. It also allows the DC/DC converters in PMIC to offer an efficiency of up to 95%.

Additionally, parameters like output voltage, power state transitions, and reset behavior can be configured using the OTP feature. According to ROHM, in designs built around the i.MX 8M Mini processors, the PMIC’s integration reduces the number of external parts and shrinks the mounting area by 42% compared to discrete solutions.

3. PMIC for low-power FPGAs
MaxLinear’s PMIC — specifically designed for low-power FPGAs, DSPs, and microprocessors — is targeted at embedded designs for the internet of things (IoT), industrial control systems, point of sale (POS) terminals, and test and measurement equipment. The five rails in the MxL7704 PMIC are pre-optimized for a host of features that provide designers additional flexibility and enable them to carry out power monitoring.

The MxL7704  power device comprises four synchronous step-down buck regulators that provide system, memory, I/O, and core with power that spans from 1.5 A to 4 A. The PMIC also features an on-board 100-mA LDO regulator that provides clean 1.5 V to 3.6 V of power for analog subsystems. Then there is a conditional sequencing state machine that can meet the requirements of virtually any processor.

Take the example of the MxL7704-X power IC that has been optimized for powering the Xilinx Zynq Ultrascale+ ZU2 and ZU3 MPSoC chips. The bucks are pre-programmed to provide the core rail from 0.85 V to 4 A, 1.35 V of power for LPDDR3 memory, and 1.8 V and 3.3 V for the I/O and system. Moreover, sequencing is tailored to the unique needs of the ZU2 and ZU3 MPSoC chips.

Next, the MxL7704-A PMIC is designed to power a wide range of Arm Cortex-based processors such as A7, A9, and A53. Here, the bucks provide the 1.2-V rail for core, 1.35 V for LPDDR3 memory, and 1.8-V and 3.3-V rails for I/O and system power.

4. Power management for IoT
Chipmakers like Dialog Semiconductor are pushing the boundaries of their power architectures to serve always-on IoT applications more efficiently, especially for smart home devices and ultra-low-power wearable gadgets such as fitness trackers and smartwatches, which are tethered to a battery charger infrequently.

Dialog’s DA9070  and DA9073  chips extend battery life by drawing less than 1 μA of quiescent current for each of the step-down regulators that power the always-on components within the system. Dialog claims that its new PMICs mark the first nano-power offering developed for IoT connectivity applications based on the Arm processors.

These PMICs integrate all key power management functions to create an all-in-one power management solution and reduce board area by 25% compared to discrete regulators. Also, in the case of the DA9070 power chip, IoT designers can take advantage of voltage- and current-monitoring features and build a battery fuel-gauge solution.

5. PMIC built around wearables
Another PMIC that is aiming to extend battery runtime while shrinking the device form factor comes from Maxim Integrated. The ultra-low-power MAX20345 is optimized for sensing highly accurate heart rate, blood-oxygen (SpO₂ ), and other optical measurements for wearable fitness and health-care applications.

In wearable designs, in which a variety of biological factors can affect the optical-sensing accuracy, designers often make a tradeoff regarding the signal-to-noise ratio (SNR) on the wrist due to high-amplitude ripple. Consequently, some developers turn to high-quiescent-current alternatives to overcome these drawbacks, but they end up with higher power consumption.

The MAX20345 PMIC optimizes the buck-boost regulator for accurate optical heart rate and SpO₂ sensing in wearables and IoT devices. (Image: Maxim Integrated)

The MAX20345 delivers low quiescent current without the drawbacks that degrade SNR and, as a result, can increase the SNR performance by up to 7 dB. It integrates a lithium-ion battery charger; six voltage regulators, each with ultra-low quiescent current; three nano-power bucks (900 nA typical); and three ultra-low quiescent current LDO regulators with current as low as 550 nA typical.

The buck-boost and bucks support dynamic voltage scaling (DVS) to provide additional power-saving opportunities when lower voltages can be deployed under favorable conditions. Additionally, there are two load switches, which disconnect the system peripherals when they are not operational to minimize the battery drain.