X51638S8 INTERSIL [Intersil Corporation], X51638S8 Datasheet - Page 3

• Manufacturer Part Number: X51638S8
• Description: CPU Supervisor with 16Kbit SPI EEPROM Description
• Manufacturer: INTERSIL [Intersil Corporation]

Principles Of Operation
Power-on Reset
Application of power to the X516, /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
exceeds the device V
circuit releases RESET/RESET, allowing the processor to
begin executing code.
Low Voltage Monitoring
During operation, the X5163, X5165 monitors the V
and asserts RESET/RESET if supply voltage falls below a
preset minimum V
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
Watchdog Timer
The Watchdog Timer circuit monitors the microprocessor
activity by monitoring the WDI input. The microprocessor
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 expiration of the watchdog
time out period. The state of two nonvolatile control bits in
the Status Register determine 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
voltage. This value will not change over normal operating
and storage conditions. However, in applications where the
standard V
the V
adjusted.
Setting the V
This procedure sets the V
example, if the current V
4.6V, this procedure directly makes the change. If the new
setting is lower than the current setting, then it is necessary
to reset the trip point before setting the new value.
CC
Threshold Reset Procedure
TRIP
CC
returns and exceeds V
value, the X5163, X5165 threshold may be
TRIP
TRIP
is not exactly right, or for higher precision in
TRIP
Voltage
TRIP
. The RESET/RESET signal prevents
TRIP
value for 200ms (nominal) the
TRIP
is 4.4V and the new V
3
to a higher voltage value. For
TRIP
CC
for 200ms.
threshold (V
CC
TRIP
TRIP
CC
level
X5163, X5165
is
)
To set the new V
threshold to the V
pin HIGH. RESET and SO pins are left unconnected. Then
apply the programming voltage V
pulse CS/WDI LOW then HIGH. Remove V
sequence is complete.
Resetting the V
This procedure sets the V
example, if the current V
the new V
must be used to set the voltage to a lower value.
To reset the V
5.5V to the V
THE SCK pin HIGH. RESET and SO pins are left
unconnected. Then apply the programming voltage V
SI pin ONLY and pulse CS/WDI LOW then HIGH. Remove V
and the sequence is complete.
SCK
SCK
CS
SI
CS
TRIP
SI
CC
FIGURE 2. RESET V
TRIP
is something less than 1.7V. This procedure
V
V
FIGURE 1. SET V
V
V
pin. Tie the CS/WDI pin, the WP pin, AND
P
CC
TRIP
P
P
CC
TRIP
voltage, apply a voltage between 2.7 and
pin and tie the CS/WDI pin and the WP
voltage, apply the desired V
Voltage
TRIP
TRIP
is 4.4V and the V
to a “native” voltage level. For
TRIP
TRIP
P
to both SCK and SI and
VOLTAGE
VOLTAGE
P
and the
TRIP
TRIP
May 16, 2005
is reset,
P
FN8128.1
to the
P