X5083
SPI Serial Memory
The memory portion of the device is a CMOS serial EEPROM
array with Intersil’s block lock protection. The array is
internally organized as x 8. The device features a Serial
Peripheral Interface (SPI) and software protocol allowing
operation on a simple four-wire bus.
The device utilizes Intersil’s proprietary Direct Write
™
cell,
providing a minimum endurance of 100,000 cycles and a
minimum data retention of 100 years.
The device is designed to interface directly with the
synchronous Serial Peripheral Interface (SPI) of many
popular microcontroller families.
The device monitors the bus and asserts RESET output if the
watchdog timer is enabled and there is no bus activity within
the user selectable time out period or the supply voltage falls
below a preset minimum V
TRIP
.
The device contains an 8-bit instruction register. It is
accessed via the SI input, with data being clocked in on the
rising edge of SCK. CS must be LOW during the entire
operation.
All instructions (Table 1), addresses and data are transferred
MSB first. Data input on the SI line is latched on the first
rising edge of SCK after CS goes LOW. Data is output on the
SO line by the falling edge of SCK. SCK is static, allowing
the user to stop the clock and then start it again to resume
operations where left off.
Write Enable Latch
The device contains a Write Enable Latch. This latch must
be SET before a Write Operation is initiated. The WREN
instruction will set the latch and the WRDI instruction will
reset the latch (Figure 7). This latch is automatically reset
upon a power-up condition and after the completion of a
valid Write Cycle.
Status Register
The RDSR instruction provides access to the status register.
The status register may be read at any time, even during a
write cycle. The status register is formatted as follows.
Status Register/Block Lock/WDT Byte
7
0
6
0
5
0
4
WD1
3
WD0
2
BL2
1
BL1
0
BL0
Block Lock Memory
Intersil’s block lock memory provides a flexible mechanism to
store and lock system ID and parametric information. There
are seven distinct block lock memory areas within the array
which vary in size from one page to as much as half of the
entire array. These areas and associated address ranges are
block locked by writing the appropriate two byte block lock
instruction to the device as described in Table 1 and Figure 9.
Once a block lock instruction has been completed, that block
lock setup is held in the nonvolatile status register until the
next block lock instruction is issued. The sections of the
memory array that are block locked can be read but not
written until block lock is removed or changed.
TABLE 1. INSTRUCTION SET AND BLOCK LOCK PROTECTION BYTE DEFINITION
INSTRUCTION FORMAT
0000 0110
0000 0100
0000 0001
INSTRUCTION NAME AND OPERATION
WREN: set the write enable latch (write enable operation)
WRDI: reset the write enable latch (write disable operation)
Write status instruction—followed by:
Block lock/WDT byte: (See Figure 1)
000WD
1
WD
2
000 --->no block lock: 00h-00h--->none of the array
000WD
1
WD
2
001 --->block lock Q1: 0000h-00FFh--->lower quadrant (Q1)
000WD
1
WD
2
010 --->block lock Q2: 0100h-01FFh--->Q2
000WD
1
WD
2
011 --->block lock Q3: 0200h-02FFh--->Q3
000WD
1
WD
2
100 --->block lock Q4: 0300h-03FFh--->upper quadrant (Q4)
000WD
1
WD
2
101 --->block lock H1: 0000h-01FFh--->lower half of the array (H1)
000WD
1
WD
2
110 --->block lock P0: 0000h-000Fh--->lower page (P0)
000WD
1
WD
2
111 --->block lock Pn: 03F0h-03FFh--->upper page (PN)
READ STATUS: reads status register & provides write in progress status on SO pin
WRITE: write operation followed by address and data
READ: read operation followed by address
0000 0101
0000 0010
0000 0011
7
FN8127.2
September 16, 2005
INTERSIL [ INTERSIL CORPORATION ]
