MACH 5 Family
11
SAFE FOR MIXED SUPPLY VOLTAGE SYSTEM DESIGNS 1
Both the 3.3-V and 5-V VCC MACH 5 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 devices will accept inputs up to 5.5 V. Both the 3.3-V and 5-V versions have the same
high-speed performance and provide easy-to-use mixed-voltage design capability.
Note:
1.
Excludes original M5-128, M5-192, and M5-256 while M5-128/1, M3-192/1 and M5-256/1 are supported. Please refer to Application Note titled “Hot
Socketing and Mixed Supply Design with MACH 4 and MACH 5 Devices”.
BUS-FRIENDLY INPUTS AND I/OS
All MACH 5 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 a 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.
POWER MANAGEMENT
There are 4 power/speed options in each MACH 5 PAL block (Table
5). The speed and power tradeoff can
be tailored for each design. The signal speed paths in the lower-power PAL blocks will be slower than those
in the higher-power PAL blocks. This feature allows speed critical paths to run at maximum frequency while
the rest of the signal paths operate in a lower-power mode. In large designs, there may be several different
speed requirements for different portions of the design.
PROGRAMMABLE SLEW RATE
Each MACH 5 device I/O has an individually programmable output slew rate control bit. Each output can be
individually configured for the higher speed transition (3 V/ns) or for the lower noise transition (1 V/ns). For
high-speed designs with long, unterminated traces, the slow-slew rate will introduce fewer reflections, less
noise, and keep ground bounce to a minimum. For designs with short traces or well terminated lines, the fast
slew rate can be used to achieve the highest speed. The slew rate is adjusted independent of power.
POWER-UP RESET/SET
All flip-flops power up to a known state for predictable system initialization. If a macrocell is configured to
SET on a signal from the control generator, then that macrocell will be SET during device power-up. If a
macrocell is configured to RESET on a signal from the control generator or is not configured for set/reset,
then that macrocell will RESET on power-up. To guarantee initialization values, the VCC rise must be
monotonic and the clock must be inactive until the reset delay time has elapsed.
Table 5. Power Levels
High Speed/High Power
100% Power
Medium High Speed/Medium High Power
67% Power
Medium Low Speed/Medium Low Power
40% Power
Low Speed/Low Power
20% Power
Select
devices
have
been
discontinued.
See
Ordering
Information
section
for
product
status.