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ISPMACH4ACPLDFAMILY Datasheet(PDF) 6 Page - Lattice Semiconductor |
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ISPMACH4ACPLDFAMILY Datasheet(HTML) 6 Page - Lattice Semiconductor |
6 / 62 page ![]() 6 ispMACH 4A Family Table 4. Architectural Summary of ispMACH 4A devices The Macrocell-I/O cell ratio is defined as the number of macrocells versus the number of I/O cells internally in a PAL block (Table 4). The central switch matrix takes all dedicated inputs and signals from the input switch matrices and routes them as needed to the PAL blocks. Feedback signals that return to the same PAL block still must go through the central switch matrix. This mechanism ensures that PAL blocks in ispMACH 4A devices communicate with each other with consistent, predictable delays. The central switch matrix makes a ispMACH 4A device more advanced than simply several PAL devices on a single chip. It allows the designer to think of the device not as a collection of blocks, but as a single programmable device; the software partitions the design into PAL blocks through the central switch matrix so that the designer does not have to be concerned with the internal architecture of the device. Each PAL block consists of: x Product-term array x Logic allocator x Macrocells x Output switch matrix x I/O cells x Input switch matrix x Clock generator Notes: 1. M4A3-64/64 internal switch matrix functionality embedded in central switch matrix. ispMACH 4A Devices M4A3-64/32, M4A5-64/32 M4A3-96/48, M4A5-96/48 M4A3-128/64, M4A5-128/64 M4A3-192/96, M4A5-192/96 M4A3-256/128, M4A5-256/128 M4A3-384 M4A3-512 M4A3-32/32 M4A5-32/32 M4A3-64/64 M4A3-256/160 M4A3-256/192 Macrocell-I/O Cell Ratio 2:1 1:1 Input Switch Matrix Yes Yes1 Input Registers Yes No Central Switch Matrix Yes Yes Output Switch Matrix Yes Yes |