Multi-output power management ICs in infotainment systems: Page 3 of 8

October 30, 2013 //By Steve Knoth, Jeff Marvin, Linear Technology Corporation
Multi-output power management ICs in infotainment systems
With automotive infotainment systems being increasingly incorporating highly integrated and very powerful microprocessors and FPGAs, power management for these infotainment systems is growing more complex. A solution that helps to keep the designs simple is multi-output power management chips.
performance aspects of a PMIC design. Some are straightforward, such as the DC-DC switching regulators must operate at a fixed frequency well outside of the AM radio band. However, another common radiated emission source found in DC-DC converters comes from the switching edge rates of its internal power MOSFETs. These edge rates should be controlled to reduce radiated emissions.

Many of today’s embedded systems and advanced processors require controlled and choreographed sequencing as power supplies are powered up and applied to various circuits. Allowing for system flexibility and a simple approach to sequencing not only makes the system design easier, but it also enhances system reliability and allows for a single PMIC to handle a broader range of the system than just a specific processor’s requirements.

In summary, the main challenges facing the automotive infotainment system designer include the following:

  • Balancing power dissipation with the high level of integration of multiple switching regulators and linear regulators
  • Accurate output voltage regulation and load step response required by advanced nano-meter technology processors and FPGAs.
  • Monitoring junction temperatures
  • Immunity to radiated and conducted noise, with low emissions contributions
  • Large voltage transients and temperature extremes
  • Managing power sequencing during startup and shutdown
  • Minimizing solution size and footprint.

A Simple Solution

Historically, many PMICs have not possessed the necessary power to handle these modern systems and microprocessors. Any solution to satisfy the automotive power management IC design constraints as already outlined must combine a high level of integration, including high-current switching regulators and LDOs, wide temperature range of operation, power sequencing and dynamic I2C control of key parameters with hard-to-do functional blocks. Furthermore, a device with high switching frequency reduces the size of external components and ceramic capacitors reduce output ripple. This low ripple combines with accurate, fast response regulators to satisfy demanding voltage tolerances of 45nm type processors. Such power ICs must also be capable of meeting the rigorous automotive environment including radiated emission

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