v4.0

5

P ack ag e Th er m a l Ch ar ac t e r i st i c s

The device junction to case thermal characteristic is

θjc,

and the junction to ambient air characteristic is

θja. The

thermal characteristics for

θja are shown with two different

air flow rates.

Maximum junction temperature is 150°C.

A sample calculation of the absolute maximum power

dissipation allowed for a PQFP 160-pin package at

commercial temperature is as follows:

P o w e r D i s s ip a t io n

Where:

are changing.

An accurate determination of N and M is problematical

because their values depend on the family type, design

details, and on the system I/O. The power can be divided

into two components: static and active.

S tat i c P o w e r Co m ponen t

Actel FPGAs have small static power components that

result in lower power dissipation than PALs or PLDs. By

integrating multiple PALs/PLDs into one FPGA, an even

greater reduction in board-level power dissipation can be

achieved.

The power due to standby current is typically a small

component of the overall power. Standby power is

calculated below for commercial, worst case conditions.

Power

2 mA

5.25V

10.5 mW

The static power dissipated by TTL loads depends on the

number of outputs driving high or low and the DC load

current. Again, this value is typically small. For instance, a

32-bit bus sinking 4 mA at 0.33 V will generate 42 mW with

all outputs driving low, and 140 mW with all outputs driving

high. The actual dissipation will average somewhere

between as I/Os switch states with time.

Ac ti v e P o wer Com p o nent

Power dissipation in CMOS devices is usually dominated by

the active (dynamic) power dissipation. This component is

frequency dependent, 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 capacitance due to PC board traces

Package Type

Pin Count

θjc

θja

Still Air

θja

300 ft/min

Units

Ceramic Pin Grid Array

100

132

176

5

5

8

35

30

23

17

15

12

°C/W

°C/W

°C/W

Ceramic Quad Flat Pack

172

8

25

15

°C/W

100

144

160

13

15

15

48

40

38

40

32

30

°C/W

°C/W

°C/W

84

12

37

28

°C/W

100

12

43

35

°C/W

176

15

32

25

°C/W

Notes:(Maximum Power in Still Air)

1.

Maximum Power Dissipation for PQFP packages are 1.9 Watts (100-pin), 2.3 Watts (144-pin), and 2.4 Watts (160-pin).

2.

Maximum Power Dissipation for PLCC packages is 2.7 Watts.

3.

Maximum Power Dissipation for VQFP packages is 2.3 Watts.

4.

Maximum Power Dissipation for TQFP packages is 3.1 Watts.

Max. junction temp. (°C) – Max. commercial temp.

θja (°C/W)

-----------------------------------------------------------------------------------------------------------------------------

150°C – 70°C

33°C/W

---------------------------------

2.4 W

==