X5165 XICOR [Xicor Inc.], X5165 Datasheet - Page 3

• Manufacturer Part Number: X5165
• Description: CPU Supervisor with 16Kbit SPI EEPROM
• Manufacturer: XICOR [Xicor Inc.]

X5163/X5165 – Preliminary Information
PRINCIPLES OF OPERATION
Power On Reset
Application of power to the X5163/X5165 activates a
Power On Reset Circuit. This circuit goes active at 1V
and pulls the RESET/RESET pin active. This signal
prevents the system microprocessor from starting to
operate with insufficient voltage or prior to stabilization
of the oscillator. When V
value for 200ms (nominal) the circuit releases RESET/
RESET, allowing the processor to begin executing code.
Low Voltage Monitoring
During operation, the X5163/X5165 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 a RESET/RESET signal. The CS/WDI pin
must be toggled from HIGH to LOW prior to the expira-
tion of the watchdog time out period. The state of two
nonvolatile control bits in the Status Register deter-
mine the watchdog timer period. The microprocessor
can change these watchdog bits, or they may be
“locked” by tying the WP pin LOW and setting the
WPEN bit HIGH.
V
The X5163/X5165 has a standard V
(V
operating and storage conditions. However, in applica-
tions where the standard V
for higher precision in the V
X5165 threshold may be adjusted.
Setting the V
This procedure sets the V
value. For example, if the current V
new V
change. If the new setting is lower than the current set-
ting, then it is necessary to reset the trip point before
setting the new value.
REV 1.1 3/5/01
TRIP
CC
TRIP
Threshold Reset Procedure
for 200ms.
TRIP
) voltage. This value will not change over normal
is 4.6V, this procedure directly makes the
TRIP
Voltage
CC
TRIP
TRIP
exceeds the device V
TRIP
CC
TRIP
. The RESET/RESET
is not exactly right, or
returns and exceeds
to a higher voltage
TRIP
value, the X5163/
is 4.4V and the
CC
threshold
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TRIP
CC
To set the new V
threshold to the V
the WP pin HIGH. RESET and SO pins are left uncon-
nected. Then apply the programming voltage V
both SCK and SI and pulse CS/WDI LOW then HIGH.
Remove V
Figure 1. Set V
Resetting the V
This procedure sets the V
level. For example, if the current V
V
1.7V. This procedure must be used to set the voltage to
a lower value.
To reset the V
2.7 and 5.5V to the V
WP pin, AND THE SCK pin HIGH. RESET and SO
pins are left unconnected. Then apply the program-
ming voltage V
LOW then HIGH. Remove V
complete.
Figure 2. Reset V
TRIP
is reset, the new V
SCK
SCK
CS
CS
SI
SI
P
and the sequence is complete.
V
V
V
V
P
TRIP
P
CC
P
P
TRIP
TRIP
to the SI pin ONLY and pulse CS/WDI
TRIP
Characteristics subject to change without notice.
CC
TRIP
voltage, apply a voltage between
Voltage
Voltage
pin and tie the CS/WDI pin and
voltage, apply the desired V
CC
Voltage
pin. Tie the CS/WDI pin, the
TRIP
TRIP
P
is something less than
and the sequence is
to a “native” voltage
TRIP
is 4.4V and the
3 of 21
TRIP
P
to