R
XC1800 Series of In-System Programmable Configuration PROMs
In-System Programming
One or more in-system programmable PROMs can be
daisy chained together and programmed in-system via the
standard 4-pin JTAG protocol as shown in
Figure 2.
In-sys-
tem programming offers quick and efficient design itera-
tions and eliminates unnecessary package handling or
socketing of devices. The Xilinx development system pro-
vides the programming data sequence using Xilinx JTAG
Programmer software and a download cable, a third-party
JTAG development system, a JTAG-compatible board
tester, or a simple microprocessor interface that emulates
the JTAG instruction sequence.
All outputs are 3-stated or held at clamp levels during in-
system programming.
Reliability and Endurance
Xilinx in-system programmable products provide a mini-
mum endurance level of 10,000 in-system program/erase
cycles and a minimum data retention of 10 years. Each
device meets all functional, performance, and data reten-
tion specifications within this endurance limit.
Design Security
The Xilinx in-system programmable PROM devices incor-
porate advanced data security features to fully protect the
programming data against unauthorized reading.
Table 2
shows the security setting available.
The read security bit can be set by the user to prevent the
internal programming pattern from being read or copied via
JTAG. When set it allows device erase. Erasing the entire
device is the only way to reset the read security bit.
Table 2: Data Security Options
Default
Read Allowed
Program/Erase Allowed
Set
Read Inhibited via JTAG
Erase Allowed
External Programming
Xilinx reprogrammable PROMs can also be programmed
by the Xilinx HW-130 device programmer. This provides the
added flexibility of using pre-programmed devices in
design, boundary-scan manufacturing tools, with an in-sys-
tem programmable option for future enhancements and
design changes.
V
CC
GND
(a)
(b)
X5902
Figure 2: In-System Programming Operation (a) solder device to PCB and (b) Program using Download Cable
September 17, 1999 (Version 1.3)
5
XILINX [ XILINX, INC ]
