X51638
CPU Supervisor with 16Kb SPI EEPROM
FEATURES
DESCRIPTION
• Extended Power-On Reset (800ms Nominal)
• Selectable Watchdog Timer
This device combines four popular functions, Power-on
Reset Control, Watchdog Timer, Supply Voltage Supervi-
sion, and Block Lock™ Protect Serial EEPROM in one
package. This combination lowers system cost, reduces
board space requirements, and increases reliability.
• Low Vcc Detection and Reset Assertion
—Five Standard Reset Threshold Voltages
—Re-program Low Vcc Reset Threshold Voltage
using special programming sequence
—Reset Signal Valid to Vcc=1V
Applying power to the device activates a power on reset
circuit which holds RESET active for a period of time.
This allows the power supply and oscillator to stabilize
before the processor can execute code. This device
allows 800ms before releasing the controller.
• Determine Watchdog or Low Voltage Reset with
a Volatile Flag bit
• Long Battery Life With Low Power Consumption
—<50mA Max Standby Current, Watchdog On
—<1mA Max Standby Current, Watchdog Off
—<400mA Max Active Current during Read
• 16Kbits of EEPROM
• Built-in Inadvertent Write Protection
—Power-Up/Power-Down Protection Circuitry
—Protect 0, 1/4, 1/2 or all of EEPROM Array with
Block LockTM Protection
The Watchdog Timer provides an independent protection
mechanism for microcontrollers. When the microcontrol-
ler fails to restart a timer within a selectable time-out
interval, the device activates the RESET signal. The user
selects the interval from three preset values. Once
selected, the interval does not change, even after cycling
the power.
—In Circuit Programmable ROM Mode
• 2MHz SPI Interface Modes (0,0 & 1,1)
• Minimize EEPROM Programming Time
—32 Byte Page Write Mode
—Self-Timed Write Cycle
—5ms Write Cycle Time (Typical)
The X51638 low Vcc detection circuitry protects the
user’s system from low voltage conditions, resetting the
system when Vcc falls below the minimum Vcc trip point.
RESET is asserted until Vcc returns to proper operating
level and stabilizes. Five industry standard V
thresh-
TRIP
olds are available, however, Xicor’s unique circuits allow
the thresold to be reprogrammed to meet custom
requirements or to fine-tune the threshold for applications
requiring higher precision.
• 1.8V to 3.6V, 2.7V to 5.5V and 4.5V to 5.5V Power
Supply Operation
• Available Packages
—14-Lead TSSOP, 8-Lead SOIC
BLOCK DIAGRAM
WATCHDOG TRANSITION
DETECTOR
WATCHDOG
TIMER RESET
WP
PROTECT LOGIC
RESET
SI
DATA
STATUS
REGISTER
SO
REGISTER
COMMAND
DECODE &
CONTROL
LOGIC
RESET &
WATCHDOG
TIMEBASE
SCK
4K BITS
4K BITS
CS/WDI
VCC THRESHOLD
RESET LOGIC
8K BITS
POWER ON AND
LOW VOLTAGE
RESET
V
+
-
CC
GENERATION
V
TRIP
ÓXicor, Inc. 1999 Patents Pending
9900-3002.10 2/12/99 T0/C0/D0
Characteristics subject to change without notice
1
ETC [ ETC ]
