APPLICATION NOTES
A V A I L A B L E
AN19 • AN38 • AN41 • AN61
X25640
64K
X25640
8K x 8 Bit
Advanced SPI Serial E2PROM With Block LockTM Protection
FEATURES
DESCRIPTION
The X25640 is a CMOS 65,536-bit serial E2PROM,
internally organized as 8K x 8. The X25640 features a
Serial Peripheral Interface (SPI) and software protocol
allowing operation on a simple three-wire bus. The bus
signalsareaclockinput(SCK)plusseparatedatain(SI)
and data out (SO) lines. Access to the device is con-
trolled through a chip select (CS) input, allowing any
number of devices to share the same bus.
• 1MHz Clock Rate
• Low Power CMOS
—200µA Standby Current
—5mA Active Current
• 5 Volt Power Supply
• SPI Modes (0,0 & 1,1)
• 8K X 8 Bits
—32 Byte Page Mode
• Block Lock Protection
—Protect 1/4, 1/2 or all of E2PROM Array
• Built-in Inadvertent Write Protection
—Power-Up/Power-Down protection circuitry
—Write Enable Latch
The X25640 also features two additional inputs that
provide the end user with added flexibility. By asserting
the HOLD input, the X25640 will ignore transitions on its
inputs, thus allowing the host to service higher priority
interrupts.TheWPinputcanbeusedasahardwireinput
to the X25640 disabling all write attempts to the status
register, thus providing a mechanism for limiting end
usercapabilityofaltering0, 1/4, 1/2orallofthememory.
—Write Protect Pin
• Self-Timed Write Cycle
—5ms Write Cycle Time (Typical)
• High Reliability
The X25640 utilizes Xicor’s proprietary Direct Write™
cell, providing a minimum endurance of 100,000 cycles
and a minimum data retention of 100 years.
—Endurance: 100,000 cycles
—Data Retention: 100 Years
—ESD protection: 2000V on all pins
• 8-Lead PDlP Package
• 14-Lead SOIC Package
FUNCTIONAL DIAGRAM
WRITE
STATUS
PROTECT
REGISTER
LOGIC
X DECODE
LOGIC
8K BYTE
ARRAY
64
64
64 X 256
64 X 256
SO
COMMAND
DECODE
AND
CONTROL
LOGIC
SI
SCK
CS
HOLD
128
128 X 256
WRITE
CONTROL
AND
TIMING
LOGIC
WP
32
8
Y DECODE
DATA REGISTER
3089 ILL F01
Direct Write™ and Block Lock™ Protection is a trademark of Xicor, Inc.
©Xicor, Inc. 1994, 1995, 1996 Patents Pending
3089-1.8 6/17/96 T4/C4/D1 NS
Characteristics subject to change without notice
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