X5168 INTERSIL [Intersil Corporation], X5168 Datasheet - Page 4

• Manufacturer Part Number: X5168
• Description: CPU Supervisor with 16Kbit SPI EEPROM
• Manufacturer: INTERSIL [Intersil Corporation]

Principles of Operation
Power-on Reset
Application of power to the X5168, X5169 activates a power-
on reset circuit. This circuit goes active at about 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
(nominal) the circuit releases RESET/RESET, allowing the
processor to begin executing code.
Low Voltage Monitoring
During operation, the X5168, X5169 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
V
The X5168, X5169 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.
To set the new V
threshold to the V
HIGH. RESET/RESET and SO pins are left unconnected.
Then apply the programming voltage V
and pulse CS LOW then HIGH. Remove V
sequence is complete.
CC
Threshold Reset Procedure
TRIP
CC
CC
SCK
returns and exceeds V
SI
CS
value, the X5168, X5169 threshold may be
TRIP
exceeds the device V
V
V
TRIP
FIGURE 1. SET V
is not exactly right, or for higher precision in
P
P
TRIP
CC
TRIP
Voltage
pin and tie the CS pin and the WP pin
voltage, apply the desired V
. The RESET/RESET signal prevents
TRIP
TRIP
is 4.4V and the new V
4
to a higher voltage value. For
TRIP
TRIP
TRIP
VOLTAGE
CC
value for 200ms
for 200ms.
P
threshold (V
to both SCK and SI
P
and the
TRIP
CC
TRIP
TRIP
level
X5168, X5169
is
)
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 Vcc pin. Tie the CS pin, the WP pin, and the SCK
pin HIGH. RESET/RESET and SO pins are left unconnected.
Then apply the programming voltage V
and pulse CS LOW then HIGH. Remove V
sequence is complete.
SCK
SI
CS
TRIP
FIGURE 2. RESET V
TRIP
V
is something less than 1.7V. This procedure
V
P
CC
TRIP
voltage, apply a voltage between 2.7 and
Voltage
TRIP
TRIP
is 4.4V and the V
to a “native” voltage level. For
TRIP
VOLTAGE
P
to the SI pin ONLY
P
and the
September 16, 2005
TRIP
is reset,
FN8130.1