9
ATF1504ASV(L)
1409H–PLD–09/02
All power-down AC characteristic parameters are computedfromexternal input or I/O
pins, with reduced-powerbitturnedon. For macrocells in reduced-powermode
(reduced-powerbitturned on), the reduced-power adder, t
RPA
,mustbe addedtothe AC
parameters, which include the data paths t
LAD
,t
LAC
,t
IC
,t
ACL
,t
ACH
and t
SEXP
.
The ATF1504ASV(L)macrocell also has an option whereby the powercanbe reduced
on a permacrocell basis. By enabling this power-down option, macrocells that are not
used in an application can be turned down, thereby reducing the overall power con-
sumption of the device.
Each output also has individual slewrate control. This may be usedtoreduce system
noise by slowing down outputs that do not needtooperate at maximum speed. Outputs
default to slow switching, and may be specified as fast switching in the design file.
Design Software
Support
ATF1504ASV(L)designs are supportedbyseveral industry standard third party tools.
Automatedfitters allow logic synthesis using a variety of high-leveldescription lan-
guages and formats.
Power-up Reset The ATF1504ASV is designed with a power-up reset, a feature critical for state machine
initialization. At a point delayedslightlyfromV
CC
crossing V
RST
,allregisters will be ini-
tialized, and the state of each output will depend on the polarity of its buffer.However,
due to the asynchronous nature of resetanduncertainty of how V
CC
actually risesinthe
system, the following conditions are required:
1. The V
CC
rise must be monotonic,
2. Afterreset occurs, all input and feedback setup timesmustbe metbefore driving
the clock pin high, and,
3. The clock must remain stable during T
D
.
The ATF1504ASV has two options for the hysteresis about the resetlevel, V
RST
,Small
and Large. To ensure a robust operating environment in applications where the device
is operatednear 3.0V, Atmelrecommends that during the fitting process users configure
the device with thePower-up Resethysteresis settoLarge. For conversions, Atmel
POF2JED users should include the flag “-power_reset” on the command line after “file-
name.POF”. To allow the registers to be properly reinitializedwiththeLarge hysteresis
option selected, the following condition is added:
4. If V
CC
falls below 2.0V, it must shut off completely before the device is turnedon
again.
WhentheLarge hysteresisoptionisactive,I
CC
is reducedbyseveral hundredmicro-
amps as well.
Security Fuse Usage Asingle fuse is providedtoprevent unauthorized copying of the ATF1504ASV(L)fuse
patterns. Once programmed, fuseverify is inhibited.However, the16-bit User Signature
remains accessible.
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