Mixed Voltage Design Considerations; Overview; Required Power Supplies - Intel PXA27 Series Design Manual

Mixed Voltage Design Considerations

4.1

Overview

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system that provides the best possible power utilization. The power management system requires
design of several voltage supplies into your system. Use a sophisticated power management
integrated circuit (PMIC) in your system in order to utilize all the power savings possible with the
PXA27x processor.
However, it is not required to incorporate a PMIC into a PXA27x processor-based system. By
using four separate power regulators (optionally five), developing a power management system is
possible for the PXA27x processor. However, the trade-off for such simplicity is increased power
consumption and loss of flexibility in peripheral voltage selection and added requirements for
battery backup.
4.2

Required Power Supplies

See Table 4-1
PXA27x processor. By careful selection, the three voltage supplies can supply the nine voltages.
Using a 1.1 V, a 1.3 V, and a 3.3 V supply (all regulated at ±10%), satisfy all requirements for the
nine voltage domains.
A fourth voltage regulator supplies the voltage for VCC_BATT. While the supplied voltage is the
same voltage as a regulator already included in the design, a separate regulator must provide the
supplied voltage in order to keep the voltage draw to a minimum. The current required to supply
VCC_BATT is very small and so use a regulator with very small current source capability and
correspondingly small current draw for the voltage supply. The other 3.3 V regulator powers the
peripherals and must have much larger current sourcing capabilities. In a handheld system, the
power draw for the voltage supply is not acceptable.
The trade-off for simplifying these nine supplies to three is that the peripheral supply voltages must
all be 3.3 V. If 3.3 V is unacceptable to the system design, adding a fifth regulator of 1.8 V allows
greater flexibility in the design without dramatically increasing the system cost or complexity. The
addition of a fifth regulator also allows for a mixture of 3.3 V and 1.8 V peripherals for use in the
system design.
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Intel PXA27x Processor Family Design Guide
PXA27x Processor Family (PXA27x processor) uses a complex power management
for the lists of the required power supplies and their associated values for the
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