ispMACH 4A Family
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IEEE 1149.1-COMPLIANT BOUNDARY SCAN TESTABILITY
All ispMACH 4A devices have boundary scan cells and are compliant to the IEEE 1149.1 standard. This
allows functional testing of the circuit board on which the device is mounted through a serial scan path that
can access all critical logic nodes. Internal registers are linked internally, allowing test data to be shifted in
and loaded directly onto test nodes, or test node data to be captured and shifted out for verification. In
addition, these devices can be linked into a board-level serial scan path for more complete board-level
testing.
IEEE 1149.1-COMPLIANT IN-SYSTEM PROGRAMMING
Programming devices in-system provides a number of significant benefits including: rapid prototyping,
lower inventory levels, higher quality, and the ability to make in-field modifications. All ispMACH 4A
devices provide In-System Programming (ISP) capability through their Boundary ScanTest Access Ports.
This capability has been implemented in a manner that ensures that the port remains compliant to the IEEE
1149.1 standard. By using IEEE 1149.1 as the communication interface through which ISP is achieved,
customers get the benefit of a standard, well-defined interface.
ispMACH 4A devices can be programmed across the commercial temperature and voltage range. The PC-
based ispVM software facilitates in-system programming of ispMACH 4A devices. ispVM takes the
JEDEC file output produced by the design implementation software, along with information about the
JTAG chain, and creates a set of vectors that are used to drive the JTAG chain. ispVM software can use
these vectors to drive a JTAG chain via the parallel port of a PC. Alternatively, ispVM software can output
files in formats understood by common automated test equipment. This equpment can then be used to
program ispMACH 4A devices during the testing of a circuit board.
PCI COMPLIANT
ispMACH 4A devices in the -5/-55/-6/-65/-7/-10/-12 speed grades are compliant with the PCI Local Bus
Specification version 2.1, published by the PCI Special Interest Group (SIG). The 5-V devices are fully PCI-
compliant. The 3.3-V devices are mostly compliant but do not meet the PCI condition to clamp the inputs
as they rise above VCC because of their 5-V input tolerant feature.
SAFE FOR MIXED SUPPLY VOLTAGE SYSTEM DESIGNS
Both the 3.3-V and 5-V VCC ispMACH 4A devices are safe for mixed supply voltage system designs. The
5-V devices will not overdrive 3.3-V devices above the output voltage of 3.3 V, while they accept inputs
from other 3.3-V devices. The 3.3-V device will accept inputs up to 5.5 V. Both the 5-V and 3.3-V versions
have the same high-speed performance and provide easy-to-use mixed-voltage design capability.
PULL UP OR BUS-FRIENDLY INPUTS AND I/Os
All ispMACH 4A devices have inputs and I/Os which feature the Bus-Friendly circuitry incorporating two
inverters in series which loop back to the input. This double inversion weakly holds the input at its last
driven logic state. While it is good design practice to tie unused pins to a known state, the Bus-Friendly input
structure pulls pins away from the input threshold voltage where noise can cause high-frequency switching.
At power-up, the Bus-Friendly latches are reset to a logic level “1.” For the circuit diagram, please refer to
the document entitled MACH Endurance Characteristics on the Lattice Data Book CD-ROM or Lattice web
site.
All ispMACH 4A devices have a programmable bit that configures all inputs and I/Os with either pull-up
or Bus-Friendly characteristics. If the device is configured in pull-up mode, all inputs and I/O pins are