X5001 XICOR [Xicor Inc.], X5001 Datasheet - Page 3

• Manufacturer Part Number: X5001
• Description: CPU Supervisor
• Manufacturer: XICOR [Xicor Inc.]

X5001
PRINCIPLES OF OPERATION
Power On Reset
Application of power to the X5001 activates a Power On
Reset Circuit. This circuit goes active at 1V and pulls the
RESET/RESET pin active. This signal prevents the sys-
tem microprocessor from starting to operate with insuffi-
cient voltage or prior to stabilization of the oscillator. When
Vcc exceeds the device V
the circuit releases RESET, allowing the processor to
begin executing code.
Low voltage monitoring
During operation, the X5001 monitors the V
asserts RESET if supply voltage falls below a preset mini-
mum V
sor from operating in a power fail or brownout condition.
The RESET signal remains active until the voltage drops
below 1V. It also remains active until Vcc returns and
exceeds 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 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
Watchdog Register determine the watchdog timer period.
Vcc Threshold Reset Procedure
The X5001 is shipped with a standard Vcc threshold
(V
operating and storage conditions. However, in applica-
tions where the standard V
higher precision is needed in the V
threshold may be adjusted. The procedure is described
below, and requires the application of a high voltage con-
trol signal.
Setting the V
This procedure is used to set the V
age value. For example, if the current V
the new V
the change. If the new setting is to be lower than the cur-
rent setting, then it is necessary to reset the trip point
before setting the new value.
TRIP
) voltage. This value will not change over normal
TRIP
TRIP
TRIP
. The RESET signal prevents the microproces-
TRIP
for 200ms.
is 4.6V, this procedure will directly make
Voltage
TRIP
TRIP
value for 200ms (nominal)
is not exactly right, or if
TRIP
TRIP
value, the X5001
TRIP
to a higher volt-
CC
is 4.4V and
level and
3
To set the new V
threshold voltage to the Vcc pin and tie the W
programming voltage V
command sequence is sent to the device over the SPI
interface. This V
pulling CS LOW, then clocking in data 03h, 00h and 01h.
This is followed by bringing CS HIGH then LOW and
clocking in data 02h, 00h, and 01h (in order) and bringing
CS HIGH. This initiates the V
sequence. V
Resetting the V
This procedure is used to set the V
age level. For example, if the current V
the new V
reset. When V
less than 1.7V. This procedure must be used to set the
voltage to a lower value.
To reset the V
Vcc pin and tie the W
Vp. Then a V
device over the SPI interface. This V
sequence consists of pulling CS LOW, then clocking in
data 03h, 00h and 01h. This is followed by bringing CS
HIGH then LOW and clocking in data 02h, 00h, and 03h
(in order) and bringing CS HIGH. This initiates the V
programming sequence. V
operation.
TRIP
P
is brought LOW to end the operation.
TRIP
TRIP
TRIP
TRIP
TRIP
must be 4.0V, then the V
TRIP
is reset, the new V
voltage, apply greater than 3V to the
command sequence is sent to the
Voltage
programming sequence consists of
PE
voltage, apply the desired V
P
pin to the programming voltage
. Then a V
P
is brought LOW to end the
TRIP
TRIP
TRIP
TRIP
TRIP
TRIP
to a “native” volt-
TRIP
programming
programming
programming
is something
PE
is 4.4V and
pin to the
must be
TRIP
TRIP