MaxLinear PMIC Powers the Raspberry Pi 4

June 25, 2019 by Scott McMahan

MaxLinear, Inc. announced that Raspberry Pi has selected the MxL7704 Universal PMIC to power its latest single-board computer, the Raspberry Pi 4. The MxL7704 is a five output universal PMIC optimized for powering low power FPGAs, DSPs, and microprocessors from 5V inputs.

MaxLinear points out that the MxL7704 already powers the popular Raspberry Pi 3 Model B+. The company says that the versatility of this PMIC allowed it to be easily re-programmed to accommodate the new current limit, sequencing, and power specifications of the upgraded SoC and surrounding ICs of the new Raspberry Pi 4.

MxL7704 provides all essential power rails required by the Raspberry Pi 4, including the low noise voltage rail for the audio circuitry.

With its I2C programmability, MaxLinear says it also handles the unique power sequencing requirements of each rail with ease. The MxL7704's I2C interface communicates with Rasberry Pi 4's SoC for dynamic voltage scaling, sequencing control, status monitoring, and PGOOD routing. These features enable the Raspberry Pi 4 to dynamically reduce the voltage to the SoC when the system is idle and boost it when the processor is running at maximum speed to save power.

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Four synchronous step-down buck regulators provide system memory, I/O, and core power from 1.5A to 4A. An on-board 100mA LDO delivers clean 1.5V to 3.6V power for analog sub-systems.

Also, an integrated 8-bit ADC with 2 external inputs and temperature sensor provides die temperature monitoring, telemetry, and additional flexibility.  The Raspberry Pi 4 uses the MxL7704's on-board ADC to determine if a high-current delivery USB power supply is connected.

The 5mm x5mm 32-pin QFN package of the MxL7704 helps the Raspberry Pi preserve its small form factor.

Raspberry Pi 4

"The MxL7704 provides five rails pre-optimized for ease of use in single-board computer systems," said James Lougheed, Vice President of Marketing for MaxLinear's High-Performance Analog Products. "The PMIC includes a host of features that allow monitoring, telemetry and additional flexibility. These unique features provide the Raspberry Pi 4 with knowledge and control of power status and efficiency to ensure peak performance during various operating conditions."

"After using the MxL7704 very successfully on the Raspberry Pi 3 Model B+, we were very pleased to select it again to power our next generation Raspberry Pi 4 Model B computer," said James Adams, Chief Operating Officer for Raspberry Pi (Trading) Ltd. "The combination of highly efficient, high current buck supplies in a very cost-effective package which also included I2C control, dynamic voltage scaling, programmable sequencing as well as a low noise LDO and ADC has been key to making sure we have met our design and cost targets for Raspberry Pi 4."