A42MX09-3CQG100B View Datasheet(PDF) - Microsemi Corporation

Part Name

Description

Manufacturer

A42MX09-3CQG100B

40MX and 42MX FPGA Families

Microsemi Corporation 

40MX and 42MX FPGA Families

Power Dissipation

The general power consumption of MX devices is made up of static and dynamic power and can be

expressed with the following equation:

General Power Equation

P = [ICCstandby + ICCactive] * VCCI + IOL* VOL* N + IOH * (VCCI – VOH) * M

where:

ICCstandby is the current flowing when no inputs or outputs are changing.

ICCactive is the current flowing due to CMOS switching.

IOL, IOH are TTL sink/source currents.

VOL, VOH are TTL level output voltages.

N equals the number of outputs driving TTL loads to VOL.

M equals the number of outputs driving TTL loads to VOH.

Accurate values for N and M are difficult to determine because they depend on the family type, on design

details, and on the system I/O. The power can be divided into two components: static and active.

Static Power Component

The static power due to standby current is typically a small component of the overall power consumption.

Standby power is calculated for commercial, worst-case conditions. The static power dissipation by TTL

loads depends on the number of outputs driving, and on the DC load current. For instance, a 32-bit bus

sinking 4mA at 0.33V will generate 42mW with all outputs driving LOW, and 140mW with all outputs

driving HIGH. The actual dissipation will average somewhere in between, as I/Os switch states with time.

Active Power Component

Power dissipation in CMOS devices is usually dominated by the dynamic power dissipation. Dynamic

power consumption is frequency-dependent and is a function of the logic and the external I/O. Active

power dissipation results from charging internal chip capacitances of the interconnect, unprogrammed

antifuses, module inputs, and module outputs, plus external capacitances due to PC board traces and

load device inputs. An additional component of the active power dissipation is the totem pole current in

the CMOS transistor pairs. The net effect can be associated with an equivalent capacitance that can be

combined with frequency and voltage to represent active power dissipation.

The power dissipated by a CMOS circuit can be expressed by the equation:

Power (µW) = CEQ * VCCA2 * F(1)

where:

CEQ = Equivalent capacitance expressed in picofarads (pF)

VCCA = Power supply in volts (V)

F = Switching frequency in megahertz (MHz)

Equivalent Capacitance

Equivalent capacitance is calculated by measuring ICCactive at a specified frequency and voltage for

each circuit component of interest. Measurements have been made over a range of frequencies at a

fixed value of VCC. Equivalent capacitance is frequency-independent, so the results can be used over a

wide range of operating conditions. Equivalent capacitance values are shown below.

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Revision 11

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