using special programming sequence.
鈩?/div>
memory
鈥擯rotect 1/4, 1/2, all or none of EEPROM array
鈥?Built-in inadvertent write protection
鈥擶rite enable latch
鈥擶rite protect pin
鈥?3.3MHz clock rate
鈥?Minimize programming time
鈥?6-byte page write mode
鈥擲elf-timed write cycle
鈥?ms write cycle time (typical)
鈥?SPI modes (0,0 & 1,1)
鈥?Available packages
鈥?-lead MSOP, 8-lead SOIC, 8-pin PDIP
鈥?4-lead TSSOP
BLOCK DIAGRAM
Watchdog Transition
Detector
WP
SI
SO
SCK
Data
Register
Command
Decode &
Control
Logic
V
CC
Threshold
Reset Logic
DESCRIPTION
These devices combine four popular functions, Power-
on Reset Control, Watchdog Timer, Supply Voltage
Supervision, and Block Lock Protect Serial EEPROM
Memory in one package. This combination lowers
system cost, reduces board space requirements, and
increases reliability.
Applying power to the device activates the power on
reset circuit which holds RESET/RESET active for a
period of time. This allows the power supply and oscil-
lator to stabilize before the processor executes code.
The Watchdog Timer provides an independent protec-
tion mechanism for microcontrollers. When the micro-
controller fails to restart a timer within a selectable
time out interval, the device activates the RESET/
RESET signal. The user selects the interval from three
preset values. Once selected, the interval does not
change, even after cycling the power.
The device鈥檚 low V
CC
detection circuitry protects the
user鈥檚 system from low voltage conditions, resetting
the system when V
CC
falls below the minimum V
CC
trip point. RESET/RESET is asserted until V
CC
returns
to proper operating level and stabilizes. Five industry
standard V
TRIP
thresholds are available, however,
Xicor鈥檚 unique circuits allow the threshold to be repro-
grammed to meet custom requirements or to 鏗乶e-tune
the threshold for applications requiring higher precision.
Watchdog
Timer Reset
Protect Logic
RESET/RESET
Status
Register
EEPROM Array
1Kbits
1Kbits
2Kbits
Reset &
Watchdog
Timebase
X5043 = RESET
X5045 = RESET
CS/WDI
V
CC
V
TRIP
+
-
Power on and
Low Voltage
Reset
Generation
REV 1.1.2 5/29/01
www.xicor.com
Characteristics subject to change without notice.
1 of 20