XC3S400AN-4FTG256I Xilinx Inc, XC3S400AN-4FTG256I Datasheet - Page 79

• Manufacturer Part Number: XC3S400AN-4FTG256I
• Description: IC FPGA SPARTAN-3AN 256FTBGA
• Manufacturer: Xilinx Inc
• Series: Spartan™-3ANr

Specifications of XC3S400AN-4FTG256I

• Number Of Logic Elements/cells: 8064
• Number Of Labs/clbs: 896
• Total Ram Bits: 368640
• Number Of I /o: 195
• Number Of Gates: 400000
• Voltage - Supply: 1.14 V ~ 1.26 V
• Mounting Type: Surface Mount
• Operating Temperature: -40°C ~ 100°C
• Package / Case: 256-LBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Sector Lockdown
Spartan-3AN FPGA In-System Flash User Guide
UG333 (v2.1) January 15, 2009
Sector Protection Enable
Sector Protection Disable
R
The Sector Protection Enable command applies the protection level specified in the
Protection
application must perform the following actions using the SPI_ACCESS design primitive.
•
•
Table 8-8: Sector Protection Enable Command Sequence
•
The Sector Protection Disable command removes protection from all sectors. To issue the
Sector Protection Disable command sequence, the FPGA application must perform the
following actions using the SPI_ACCESS design primitive.
•
•
Table 8-9: Sector Protection Disable Command Sequence
•
The ISF memory provides a mechanism called Sector Lockdown that permanently and
irreversibly protects the contents of an individual sector against any program and erase
cycles. Sector Lockdown effectively converts the erasable Flash memory sector to a one-
time programmable (OTP), read-only memory (ROM).
Sector Lockdown is useful in applications to prevent malicious attempts to alter the FPGA
configuration bitstream, program code, or security information. To prevent accidental
changes or to have selective protection, see
MOSI
MOSI
Pin
Pin
Drive CSB Low while CLK is High or on the rising edge of CLK.
On the falling edge of CLK, serially clock in the four-byte Sector Protection Enable
command sequence shown in
byte first.
After clocking in the last bit of the command sequence, drive the CSB pin High on the
falling edge of CLK. The defined sector protection level is now active.
Drive CSB Low while CLK is High or on the rising edge of CLK.
On the falling edge of CLK, serially clock in the four-byte Sector Protection Disable
command sequence shown in
byte first.
After clocking in the last bit of the command sequence, drive the CSB pin High on the
falling edge of CLK. Sector protection is now removed from all sectors.
Caution!
unlocked. Locking down a sector is irreversible.
Register. To issue the Sector Protection Enable command sequence, the FPGA
Byte 1
Byte 1
Once an ISF memory sector is locked down, it can never be erased, programmed, or
0x3D
0x3D
www.xilinx.com
Four-byte Command Sequence
Four-byte Command Sequence
Table 8-8
Table 8-9
Byte 2
Byte 2
0x2A
0x2A
“Sector Protection,” page
on the MOSI pin, most-significant bit of each
on the MOSI pin, most-significant bit of each
Byte 3
Byte 3
0x7F
0x7F
74.
Sector Lockdown
Byte 4
Byte 4
0xA9
0x9A
Sector
79