X5043 XICOR [Xicor Inc.], X5043 Datasheet - Page 3

• Manufacturer Part Number: X5043
• Description: CPU Supervisor with 4K SPI EEPROM
• Manufacturer: XICOR [Xicor Inc.]

X5043/X5045
PRINCIPLES OF OPERATION
Power On Reset
Application of power to the X5043/X5045 activates a
Power On Reset Circuit. This circuit pulls the RESET/
RESET pin active. RESET/RESET prevents the sys-
tem microprocessor from starting to operate with insuf-
ficient voltage or prior to stabilization of the oscillator.
When V
(nominal) the circuit releases RESET/RESET, allowing
the processor to begin executing code.
Low Voltage Monitoring
During operation, the X5043/X5045 monitors the V
level and asserts RESET/RESET if supply voltage falls
below a preset minimum V
signal prevents the microprocessor from operating in a
power fail or brownout condition. The RESET/RESET
signal remains active until the voltage drops below 1V.
It also remains active until V
V
Watchdog Timer
The Watchdog Timer circuit monitors the microproces-
sor activity by monitoring the WDI input. The micropro-
cessor must toggle the CS/WDI pin periodically to
prevent an active RESET/RESET signal. The CS/WDI
pin must be toggled from HIGH to LOW prior to the
expiration of the watchdog time out period. The state of
two nonvolatile control bits in the Status Register
determines the watchdog timer period. The micropro-
cessor can change these watchdog bits. With no
microprocessor action, the watchdog timer control bits
remain unchanged, even during total power failure.
Figure 1. Set V
REV 1.1.2 5/29/01
TRIP
SCK
WP
CS
SI
for 200ms.
CC
exceeds the device V
TRIP
0 1 2 3 4 5 6 7
Level Sequence (V
WREN
06h
TRIP
CC
. The RESET/RESET
TRIP
returns and exceeds
value for 200ms
CC
= desired V
0 1 2 3 4 5 6 7 8 9 10
www.xicor.com
CC
V
Write
PE
02h
TRIP
= 15-18V
V
The X5043/X5045 is shipped with a standard V
threshold (V
over normal operating and storage conditions. How-
ever, in applications where the standard V
exactly right, or if higher precision is needed in the
V
adjusted. The procedure is described below, and uses
the application of a high voltage control signal.
Setting the V
This procedure is used to set the V
age value. For example, if the current V
and the new V
make the change. If the new setting is to be lower than
the current setting, then it is necessary to reset the trip
point before setting the new value.
To set the new V
threshold voltage to the V
the programming voltage V
mand, followed by a write of Data 00h to address 01h.
CS going HIGH on the write operation initiates the
V
plete the operation.
Note: This operation also writes 00h to array address 01h.
value.)
CC
TRIP
TRIP
Threshold Reset Procedure
programming sequence. Bring WP LOW to com-
value, the X5043/X5045 threshold may be
TRIP
11
8 Bits
Address
TRIP
01h
TRIP
12 13 14 15
) voltage. This value will not change
TRIP
Characteristics subject to change without notice.
Voltage
is 4.6V, this procedure will directly
voltage, apply the desired V
CC
P
. Then send a WREN com-
pin and tie the WP pin to
TRIP
Data
00h
to a higher volt-
TRIP
TRIP
is 4.4V
is not
3 of 20
TRIP
CC