Preliminary Information
128K
X4283/85
CPU Supervisor with 128K EEPROM
DESCRIPTION
16K x 8 Bit
FEATURES
• Selectable watchdog timer
• Low V
CC
detection and reset assertion
—Four standard reset threshold voltages
—Adjust low V
CC
reset threshold voltage using
special programming sequence
—Reset signal valid to V
CC
= 1V
• Low power CMOS
—<20µA max standby current, watchdog on
—<1µA standby current, watchdog OFF
—3mA active current
• 128Kbits of EEPROM
—64 byte page write mode
—Self-timed write cycle
—5ms write cycle time (typical)
• Built-in inadvertent write protection
—Power-up/power-down protection circuitry
—Protect 0, 1/4, 1/2, all or 64, 128, 256 or 512
bytes of EEPROM array with programmable
Block Lock
™
protection
• 400kHz 2-wire interface
• 2.7V to 5.5V power supply operation
• Available packages
—8-lead SOIC
—8-lead TSSOP
BLOCK DIAGRAM
Watchdog Transition
Detector
WP
Data
Register
Command
Decode &
Control
Logic
V
CC
Threshold
Reset logic
Block Lock Control
Protect Logic
The X4283/85 combines four popular functions,
Power-on Reset Control, Watchdog Timer, Supply Volt-
age Supervision, and Block Lock protect serial
EEPROM memory in one package. This combination
lowers system cost, reduces board space require-
ments, 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 oscilla-
tor to stabilize before the processor can execute 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’s low V
CC
detection circuitry protects the
user’s system from low voltage conditions, resetting
the system when V
CC
falls below the set minimum V
CC
trip point. RESET/RESET is asserted until V
CC
returns
to proper operating level and stabilizes. Four industry
Watchdog
Timer Reset
SDA
Status
Register
EEPROM Array
8Kb 4Kb 4Kb
RESET (X4283)
RESET (X4285)
SCL
S0
S1
Reset &
Watchdog
Timebase
V
CC
V
TRIP
+
-
Power on and
Low Voltage
Reset
Generation
REV 1.17 11/27/00
www.xicor.com
Characteristics subject to change without notice.
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XICOR [ XICOR INC. ]
