Features
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High Density, High Performance Electrically Erasable Complex
Programmable Logic Device
– 256 Macrocells
– 5 Product Terms per Macrocell, Expandable up to 40 per Macrocell
– 160, 192, 208-pins
– 10 ns Maximum Pin-to-Pin Delay
– Registered Operation Up To 100 MHz
– Enhanced Routing Resources
Flexible Logic Macrocell
– D/T/Latch Configurable Flip Flops
– Global and Individual Register Control Signals
– Global and Individual Output Enable
– Programmable Output Slew Rate
– Programmable Output Open Collector Option
– Maximum Logic utilization by burying a register within a COM output
Advanced Power Management Features
– Automatic 3 mA Stand-By for “L” Version (Max.)
– Pin-Controlled 4 mA Stand-By Mode (Typical)
– Programmable Pin-Keeper Inputs and I/Os
– Reduced-Power Feature Per Macrocell
Available in Commercial and Industrial Temperature Ranges
Available in 160-pin PQFP, 192 PGA and 208-pin RQFP Packages
Advanced EE Technology
– 100% Tested
– Completely Reprogrammable
– 100 Program/Erase Cycles
– 20 Year Data Retention
– 2000V ESD Protection
– 200 mA Latch-Up Immunity
JTAG Boundary-Scan Testing to IEEE Std. 1149.1-1990 and 1149.1a-1993 Supported
Fast In-System Programmability (ISP) via JTAG
PCI-compliant
3.3 or 5.0V I/O pins
Security Fuse Feature
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High
Performance
EE-Based CPLD
ATF1516AS/L
Preliminary
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Enhanced Features
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Improved Connectivity (Additional Feedback Routing, Alternate Input Routing)
Output Enable Product Terms
D - Latch Mode
Combinatorial Output with Registered Feedback within any Macrocell
Three Global Clock Pins
ITD ( Input Transition Detection) Circuits on Global Clocks, Inputs and I/O
Fast Registered Input from Product Term
Programmable “Pin-Keeper” Option
V
CC
Power-Up Reset Option
Pull-Up Option on JTAG Pins TMS and TDI
Advanced Power Management Features
– Edge Controlled Power Down “L”
– Individual Macrocell Power Option
– Disable ITD on Global Clocks, Inputs and I/O
Rev. 0994A-A–01/98
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Block Diagram
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ATF1516AS/L
ATF1516AS/L
Description
The ATF1516AS is a high performance, high density Com-
plex Programmable Logic Device (CPLD) which utilizes
Atmel’s proven electrically erasable technology. With 256
logic macrocells and up to 164 inputs, it easily integrates
logic from several TTL, SSI, MSI, LSI and classic PLDs.
The ATF1516AS’s enhanced routing switch matrices
increase usable gate count, and increase odds of success-
ful pin-locked design modifications.
The ATF1516AS has up to 160 bi-directional I/O pins and 4
dedicated input pins, depending on the type of device pack-
age selected. Each dedicated pin can also serve as a glo-
bal control signal; register clock, register reset or output
enable. Each of these control signals can be selected for
use individually within each macrocell.
Each of the 256 macrocells generates a buried feedback,
which goes to the global bus. Each input and I/O pin also
feeds into the global bus. The switch matrix in each logic
block then selects 40 individual signals from the global bus.
Each macrocell also generates a foldback logic term, which
goes to a regional bus. Cascade logic between macrocells
in the ATF1516AS allows fast, efficient generation of com-
plex logic functions. The ATF1516AS contains eight such
Figure 1.
ATF1516AS Macrocell
logic chains, each capable of creating sum term logic with a
fan in of up to 40 product terms
The ATF1516AS macrocell, shown in Figure 1, is flexible
enough to support highly complex logic functions operating
at high speed. The macrocell consists of five sections:
product terms and product term select multiplexer;
OR/XOR/CASCADE logic; a flip-flop; output select and
enable; and logic array inputs.
Unused Macrocells are automatically disabled by the com-
piler to decrease power consumption. A Security Fuse,
when programmed, protects the contents of the
ATF1516AS. Two bytes (16 bits) of User Signature are
accessible to the user for purposes such as storing project
name, part number, revision or date. The User Signature is
accessible regardless of the state of the Security Fuse.
The ATF1516AS device is an In-System Programmable
(ISP) device. It uses the industry standard 4-pin JTAG
interface (IEEE Std. 1149.1), and is fully compliant with
JTAG’s Boundary Scan Description Language (BSDL). ISP
allows the device to be programmed without removing it
from the printed circuit board. In addition to simplifying the
manufacturing flow, ISP also allows design modifications to
be made in the field via software.
3
Product Terms and Select MUX
Each ATF1516AS macrocell has five product terms. Each
product term receives as its inputs all signals from both the
global bus and regional bus.
The product term select multiplexer (PTMUX) allocates the
five product terms as needed to the macrocell logic gates
and control signals. The PTMUX programming is deter-
mined by the design compiler, which selects the optimum
macrocell configuration.
OR/XOR/CASCADE Logic
The ATF1516AS’s logic structure is designed to efficiently
support all types of logic. Within a single macrocell, all the
product terms can be routed to the OR gate, creating a 5-
input AND/OR sum term. With the addition of the CASIN
from neighboring macrocells, this can be expanded to as
many as 40 product terms with a very small additional
delay.
The macrocell’s XOR gate allows efficient implementation
of compare and arithmetic functions. One input to the XOR
comes from the OR sum term. The other XOR input can be
a product term or a fixed high or low level. For combinato-
rial outputs, the fixed level input allows polarity selection.
For registered functions, the fixed levels allow DeMorgan
minimization of product terms. The XOR gate is also used
to emulate T- and JK-type flip-flops.
Flip Flop
The ATF1516AS’s flip flop has very flexible data and con-
trol functions. The data input can come from either the
XOR gate, from a separate product term or directly from
the I/O pin. Selecting the separate product term allows cre-
ation of a buried registered feedback within a combinatorial
output macrocell. (This feature is automatically imple-
mented by the fitter software). In addition to D, T, JK and
SR operation, the flip flop can also be configured as a flow-
through latch. In this mode, data passes through when the
clock is high and is latched when the clock is low.
The clock itself can either be the Global CLK Signal (GCK)
or an individual product term. The flip flop changes state on
the clock’s rising edge. When the GCK signal is used as
the clock, one of the macrocell product terms can be
selected as a clock enable. When the clock enable function
is active and the enable signal (product term) is low, all
clock edges are ignored. The flip flop’s asynchronous reset
signal (AR) can be either the Global Clear (GCLEAR), a
product term, or always off. AR can also be a logic OR of
GCLEAR with a product term. The asynchronous preset
(AP) can be a product term or always off.
Output Select and Enable
The ATF1516AS macrocell output can be selected as reg-
istered or combinatorial. The buried feedback signal can be
either combinatorial or registered signal regardless of
whether the output is combinatorial or registered.
The output enable multiplexer (MOE) controls the output
enable signals. Any buffer can be permanently enabled for
simple output operation. Buffers can also be permanently
disabled to allow use of the pin as an input. In this configu-
ration all the macrocell resources are still available, includ-
ing the buried feedback, expander and CASCADE logic.
The output enable for each macrocell can be selected as
either of the two dedicated OE input pins as an I/O pin con-
figured as an input, or as an individual product term.
Global Bus/Switch Matrix
The global bus contains all input and I/O pin signals as well
as the buried feedback signal from all 256 macrocells.
The Switch Matrix in each Logic Block receives as its
inputs all signals from the global bus. Under software con-
trol, up to 40 of these signals can be selected as inputs to
the Logic Block.
Foldback Bus
Each macrocell also generates a foldback product term.
This signal goes to the regional bus and is available to 16
macrocells. The foldback is an inverse polarity of one of the
macrocell’s product terms. The 16 foldback terms in each
region allows generation of high fan-in sum terms (up to 21
product terms) with a small additional delay.
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ATF1516AS/L
ATF1516AS/L
Programmable Pin-Keeper Option
for Inputs and I/Os
The ATF1516AS offers the option of programming all input
and I/O pins so that “pin keeper” circuits can be utilized.
When any pin is driven high or low and then subsequently
left floating, it will stay at that previous high or low level.
This circuitry prevents unused input and I/O lines from
floating to intermediate voltage levels, which cause unnec-
essary power consumption and system noise. The keeper
circuits eliminate the need for external pull-up resistors and
eliminate their DC power consumption.
macrocells to be configured for maximum power savings.
This feature may be selected as a design option.
All ATF1516ASs also have an optional power down mode.
In this mode, current drops to below 10 mA. When the
power down option is selected, either PD1 or PD2 pins (or
both) can be used to power down the part. The power down
option is selected in the design source file. When enabled,
the device goes into power down when either PD1 or PD2
is high. In the power down mode, all internal logic signals
are latched and held, as are any enabled outputs.
All pin transitions are ignored until the PD pin is brought
low. When the power down feature is enabled, the PD1 or
PD2 pin cannot be used as a logic input or output. How-
ever, the pin’s macrocell may still be used to generate bur-
ied foldback and cascade logic signals.
All Power-Down AC Characteristic parameters are com-
puted from external input or I/O pins, with Reduced Power
Bit turned on. For macrocells in reduced-power mode
(Reduced power bit turned on), the reduced power adder,
tRPA, must be added to the AC parameters, which include
the data paths t
LAD
, t
LAC
, t
IC
, t
ACL
, t
ACH
and t
SEXP
.
Each output also has individual slew rate control. This may
be used to reduce system noise by slowing down outputs
that do not need to operate at maximum speed. Outputs
default to slow switching, and may be specified as fast
switching in the design file.
Input Diagram
I/O Diagram
Design Software Support
ATF1516AS designs are supported by several third party
tools. Automated fitters allow logic synthesis using a variety
of high level description languages and formats.
Power Up Reset
The ATF1516AS has a power-up reset option at two differ-
ent voltage trip levels when the device is being powered
down. Within the fitter, or during a conversion, if the
“power-reset” option is turned “on” (which is the default
option), the trip levels during power up or power down is at
2.8V. The user can change this default option from “on” to
“off” (within the fitter or specify it as a switch during conver-
sion). When this is done, the voltage trip level during
power-down changes from 2.8V to 0.7V. This is to ensure a
robust operating environment.
The registers in the ATF1516AS are designed to reset dur-
ing power up. At a point delayed slightly from V
CC
crossing
V
RST
, all registers will be reset to the low state. The output
state will depend on the polarity of the buffer.
This feature is critical for state machine initialization. How-
ever, due to the asynchronous nature of reset and the
uncertainty of how V
CC
actually rises in the system, the fol-
lowing conditions are required:
Speed/Power Management
The ATF1516AS has several built-in speed and power
management features. The ATF1516AS contains circuitry
that automatically puts the device into a low power stand-
by mode when no logic transitions are occurring. This not
only reduces power consumption during inactive periods,
but also provides a proportional power savings for most
applications running at system speeds below 50 MHz.
To further reduce power, each ATF1516AS macrocell has
a Reduced Power bit feature. This feature allows individual
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Power technology
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