M4A3-256/128-10YC Lattice, M4A3-256/128-10YC Datasheet - Page 21

• Manufacturer Part Number: M4A3-256/128-10YC
• Manufacturer: Lattice

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 LatticePRO software facilitates in-system programming of ispMACH 4A devices.
LatticePRO 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. LatticePRO software can use these vectors to drive a JTAG chain via the parallel port
of a PC. Alternatively, LatticePRO 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 V
because of their 5-V input tolerant feature.
CC
SAFE FOR MIXED SUPPLY VOLTAGE SYSTEM DESIGNS
Both the 3.3-V and 5-V V
ispMACH 4A devices are safe for mixed supply voltage system
CC
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.
ispMACH 4A Family
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