M4A3-256/128-10YC Lattice, M4A3-256/128-10YC Datasheet - Page 22

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

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 weakly pulled up. 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
Each individual PAL block in ispMACH 4A devices features a programmable low-power mode,
which results in power savings of up to 50%. The signal speed paths in the low-power PAL block
will be slower than those in the non-low-power PAL block. This feature allows speed critical
paths to run at maximum frequency while the rest of the signal paths operate in the low-power
mode.
PROGRAMMABLE SLEW RATE
Each ispMACH 4A 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 V
rise must be monotonic, and the clock must be inactive until the
CC
reset delay time has elapsed.
SECURITY BIT
A programmable security bit is provided on the ispMACH 4A devices as a deterrent to
unauthorized copying of the array configuration patterns. Once programmed, this bit defeats
readback of the programmed pattern by a device programmer, securing proprietary designs from
competitors. Programming and verification are also defeated by the security bit. The bit can only
be reset by erasing the entire device.
HOT SOCKETING
ispMACH 4A devices are well-suited for those applications that require hot socketing capability.
Hot socketing a device requires that the device, when powered down, can tolerate active signals
on the I/Os and inputs without being damaged. Additionally, it requires that the effects of the
powered-down MACH devices be minimal on active signals.
22
ispMACH 4A Family