Implementing Digital Switch Matrices Using MAX Devices
Signal-routing applications such as digital switch matrices require minimal input-to-output and clock-to-output delays. MAX® devices have low propagation delays, making them ideal for digital switch matrices in communication networks and management of microprocessor buses. MAX devices can use programmable logic to integrate any signal-to-pin or pin-to-pin routing such as in switch matrices, and at the same time implement residual control logic.
A digital switch matrix essentially consists of an interconnect array and a series of multiplexers. MAX devices contain interconnect arrays and programmable logic arrays that can implement the multiplexer circuits of a switch matrix. Design engineers can enter the functionality of any digital switch matrix using hardware description language (HDL) and easily target a MAX device for implementation. Such implementation is particularly easy for designers who are already familiar with the MAX architecture and the MAX+PLUS® II environment.
In addition, the MAX+PLUS II development software supports the MUX megafunction in its library of parameterized modules (LPM). Design engineers can enter the functionality of the multiplexer circuits in the switch matrix via an easy-to-use schematic interface, which is shown below.
Figure 1. MUX Megafunction Interface
The number of I/O pins required (rather than the number of registers) is the
limiting factor in implementation of a digital switch matrix. The choice of
device is also determined by the desired pin-to-pin delays. Design engineers
have a variety of MAX devices to choose from when they need to integrate a switch
matrix. As shown below, MAX devices can satisfy different user I/O, tPD
and tCO requirements.
| Table 1. MAX 7000AE & MAX 7000B Offerings |
|
Device Family
|
Device
|
Maximum User
I/O Pins
|
Fastest tPH
(ns)
|
Fastest tCO
(ns)
|
| MAX 7000AE |
EPM7032AE |
36
|
4.5
|
3.0
|
| EPM7064AE |
68
|
4.5
|
3.1
|
| EPM7128AE |
100
|
5.0
|
3.4
|
| EPM7256AE |
164
|
5.5
|
6.5
|
| EPM7512AE |
212
|
7.5
|
4.7
|
| MAX 7000B |
EPM7032B |
36
|
3.5
|
2.3
|
| EPM7064B |
68
|
3.5
|
2.3
|
| EPM7128B |
100
|
4.0
|
2.8
|
| EPM7256B |
164
|
5.0
|
3.5
|
| EPM7512B |
212
|
5.5
|
3.9
|
With an easy-to-use design interface and a solution that is very familiar to many designers, MAX devices offer an ideal implementation for your digital switching needs.
|
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