X80000 Datasheet, PDF (31/37 Pages) Intersil Corporation – Smart Power Plug Penta-Power Sequence Controller with Hot Swap

X80000, X80001
Memory
The X80000 contains a 2kbit EEPROM memory array. This
array can contain information about manufacturing location
and dates, board configuration, fault conditions, service
history, etc. Access to this memory is through the SMBus
serial port. Read and write operations are similar to those of
the control registers, but a single command can write up to
16 bytes at one time. A single read command can return the
entire contents of the EEPROM memory.
Register and Memory Protection
In order to reduce the possibility of inadvertent changes to
either a control register of the contents of memory, several
protection mechanisms are built into the X80000. These are
a Write Enable Latch, Block Protect bits, a Write Protect
Enable bit and a Write Protect pin.
Note, a write to FDR or RSR does not require that WEL=1.
BP1 and BP0: Block Protect Bits
The Block Protect Bits, BP1 and BP0, determines which
blocks of the memory array are write protected. A write to a
protected block of memory is ignored. The block protect bits
will prevent write operations to one of four segments of the
array.
00
01
10
11
PROTECTED ADDRESSES
(SIZE)
None (Default)
C0h - FFh (64 bytes)
80h - FFh (128 bytes)
00h - FFh (256 bytes)
ARRAY LOCK
None (Default)
Upper 1/4
Upper 1/2
All
WEL: Write Enable Latch
A write enable latch (WEL) bit controls write accesses to the
nonvolatile registers and the EEPROM memory array in the
X80000. This bit is a volatile latch that powers up in the LOW
(disabled) state. While the WEL bit is LOW, writes to any
address (registers or memory) will be ignored. The WEL bit
is set by writing a “1” to the WEL bit and zeroes to the other
bits of the control register 0 (CR0). It is important to write
only 00h or 80h to the CR0 register.
Once set, WEL remains set until either it is reset to 0 (by
writing a “0” to the WEL bit and zeroes to the other bits of the
control register) or until the part powers up again.
WPEN: Write Protect Enable
The Write Protect pin and Write Protect Enable bit in the
CR1 register control the Programmable Hardware Write
Protect feature. Hardware Protection is enabled when the
WP pin is HIGH and WPEN bit is HIGH and disabled when
WP pin is LOW or the WPEN bit is LOW. When the chip is
Hardware Write Protected, non-volatile writes to all control
registers (CR1, CR2, CR3, and CR4) are disabled including
BP bits, the WPEN bit itself, and the blocked sections in the
memory Array. Only the section of the memory array that are
not block protected can be written.
TABLE 18. WRITE PROTECT CONDITIONS
WEL WP WPEN
MEMORY ARRAY
NOT BLOCK
PROTECTED
MEMORY ARRAY
BLOCK PROTECTED
WRITES TO
CR1, CR2, CR3, CR4
PROTECTION
LOW
X
X
Writes Blocked
Writes Blocked
Writes Blocked
Hardware
HIGH LOW
X
Writes Enabled
Writes Blocked
Writes Enabled
Software
HIGH HIGH LOW
Writes Enabled
Writes Blocked
Writes Enabled
Software
HIGH HIGH HIGH
Writes Enabled
Writes Blocked
Writes Blocked
Hardware
31
FN8148.0
March 18, 2005