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Low-Power Modes in Actel ProASIC3/E FPGAs
2 – Low-Power Modes in Actel ProASIC3/E FPGAs
Introduction
The demand for low-power systems and semiconductors, combined with the strong growth
observed for value-based FPGAs, is driving growing demand for low-power FPGAs. For portable
and battery-operated applications, power consumption has always been the greatest challenge.
The battery life of a system and on-board devices has a direct impact on the success of the product.
As a result, FPGAs used in these applications should meet low-power consumption requirements.
Actel ProASIC3/E FPGAs offer low power consumption capability inherited from their nonvolatile
and live-at-power-up (LAPU) flash technology. This application note describes the power
consumption and how to use different power saving modes to further reduce power consumption
for power-conscious electronics design.
Power Consumption Overview
In evaluating the power consumption of FPGA technologies, it is important to consider it from a
system point of view. Generally, the overall power consumption should be based on static, dynamic,
inrush, and configuration power. Few FPGAs implement ways to reduce static power consumption
utilizing sleep modes.
SRAM-based FPGAs use volatile memory for their configuration, so the device must be
reconfigured after each power-up cycle. Moreover, during this initialization state, the logic could
be in an indeterminate state, which might cause inrush current and power spikes. More complex
power supplies are required to eliminate potential system power-up failures, resulting in higher
costs. For portable electronics requiring frequent power-up and -down cycles, this directly affects
battery life, requiring more frequent recharging or replacement.
SRAM-Based FPGA Total Power Consumption = Pstatic + Pdynamic + Pinrush + Pconfig
EQ 2-1
ProASIC3/E Total Power Consumption = Pstatic + Pdynamic
EQ 2-2
Unlike SRAM-based FPGAs, Actel flash-based FPGAs are nonvolatile and do not require power-up
configuration. Additionally, Actel nonvolatile flash FPGAs are live at power-up and do not require
additional support components. Total power consumption is reduced as the inrush current and
configuration power components are eliminated.
Note that the static power component can be reduced in flash FPGAs (such as the ProASIC3/E
devices) by entering User Low Static mode or Sleep mode. This leads to an extremely low static
power component contribution to the total system power consumption.
The following sections describe the usage of Static (Idle) mode to reduce the power component,
User Low Static mode to reduce the static power component, and Sleep mode and Shutdown mode
summarizes the different low-power modes offered by ProASIC3/E devices.