A14100 View Datasheet(PDF) - Actel Corporation

Part Name

Description

Manufacturer

A14100

Accelerator Series FPGAs - ACT™ 3 Family

Actel Corporation 

OE

SLEW

DATAOUT

CLKB

CLKINB

CLKA

FROM

PADS

CLKINA

S0

CLKMOD

S1

INTERNAL

SIGNAL

CLKO(17)

CLOCK

DRIVERS

PAD

CLKO(16)

CLKO(15)

DATAIN

CLKO(2)

CLKO(1)

IEN

CLOCK TRACKS

INEN

OUTEN

Figure 5 • Function Diagram for I/O Pad Driver

Routed Clocks

The routed clock networks are referred to as CLK0 and CLK1.

Each network is connected to a clock module (CLKMOD)

that selects the source of the clock signal and may be driven

as follows (see Figure 6):

• externally from the CLKA pad

• externally from the CLKB pad

• internally from the CLKINA input

• internally from the CLKINB input

The clock modules are located in the top row of I/O modules.

Clock drivers and a dedicated horizontal clock track are

located in each horizontal routing channel. The function of

the clock module is determined by the selection of clock

macros from the macro library. The macro CLKBUF is used to

connect one of the two external clock pins to a clock network,

and the macro CLKINT is used to connect an internally

generated clock signal to a clock network. Since both clock

networks are identical, the user does not care whether CLK0

or CLK1 is being used. Routed clocks can also be used to drive

high fanout nets like resets, output enables, or data enables.

This saves logic modules and results in performance

increases in some cases.

Figure 6 • Clock Networks

Routing Structure

The ACT 3 architecture uses vertical and horizontal routing

tracks to connect the various logic and I/O modules. These

routing tracks are metal interconnects that may either be of

continuous length or broken into segments. Segments can be

joined together at the ends using antifuses to increase their

lengths up to the full length of the track.

Horizontal Routing

Horizontal channels are located between the rows of modules

and are composed of several routing tracks. The horizontal

routing tracks within the channel are divided into one or

more segments. The minimum horizontal segment length is

the width of a module-pair, and the maximum horizontal

segment length is the full length of the channel. Any segment

that spans more than one-third the row length is considered a

long horizontal segment. A typical channel is shown in

Figure 7. Undedicated horizontal routing tracks are used to

route signal nets. Dedicated routing tracks are used for the

global clock networks and for power and ground tie-off tracks.

Vertical Routing

Other tracks run vertically through the modules. Vertical

tracks are of three types: input, output, and long. Vertical

tracks are also divided into one or more segments. Each

segment in an input track is dedicated to the input of a

particular module. Each segment in an output track is

dedicated to the output of a particular module. Long

segments are uncommitted and can be assigned during

1-184

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