x40031v14z-bt1 Intersil Corporation, x40031v14z-bt1 Datasheet - Page 8

• Manufacturer Part Number: x40031v14z-bt1
• Description: Triple Voltage Monitor With Integrated Cpu Supervisor
• Manufacturer: Intersil Corporation

WATCHDOG TIMER
The Watchdog Timer circuit monitors the microproces-
sor activity by monitoring the SDA and SCL pins. A
standard read or write sequence to any slave address
byte restarts the watchdog timer and prevents the
WDO signal going active. A minimum sequence to
reset the watchdog timer requires four microprocessor
instructions namely, a Start, Clock Low, Clock High
and Stop. The state of two nonvolatile control bits in
the Status Register determine the watchdog timer
period. The microprocessor can change these watch-
dog bits by writing to the X40030, X40031, X40034,
X40035 control register (also refer to page 21).
Figure 4. Watchdog Restart
V1, V2 AND V3 THRESHOLD PROGRAM
PROCEDURE (OPTIONAL)
The X40030 is shipped with standard V1, V2 and V3
threshold (V
values will not change over normal operating and stor-
age conditions. However, in applications where the
standard thresholds are not exactly right, or if higher
precision is needed in the threshold value, the X40030,
X40031, X40034, X40035 trip points may be adjusted.
The procedure is described below, and uses the appli-
cation of a high voltage control signal.
Setting a V
There are two procedures used to set the threshold
voltages (V
be stored is higher or lower than the present value. For
example, if the present V
V
into the V
lower than the present setting, then it is necessary to
“reset” the V
Setting a Higher V
To set a V
higher than the present threshold, the user must apply
the desired V
sponding input pin (Vcc(V1MON), V2MON or V3MON).
Then, a programming voltage (Vp) must be applied to
the WDO pin before a START condition is set up on
SDA. Next, issue on the SDA pin the Slave Address
SCL
SDA
TRIPx
is 3.2 V, the new voltage can be stored directly
TRIPx
TRIPx
TRIPx
TRIPx
Start
TRIPx
TRIP1,
TRIPx
.6µs
cell. If however, the new setting is to be
), depending if the threshold voltage to
threshold to a new voltage which is
Voltage (x=1, 2, 3)
voltage before setting the new value.
TRIPx
V
threshold voltage to the corre-
TRIP2,
Voltage (x=1, 2, 3)
1.3µs
TRIPx
8
V
TRIP3
is 2.9 V and the new
WDT Reset
) voltages. These
X40030, X40031, X40034, X40035
Stop
A0h, followed by the Byte Address 01h for V
for V
order to program V
write operation initiates the programming sequence. Pin
WDO must then be brought LOW to complete the oper-
ation. To check if the V
to a value slightly greater than V
ously set). Slowly ramp down VXMON and observe
when the corresponding outputs (LOWLINE, V2FAIL
and V3FAIL) switch. The voltage at which this occurs is
the V
C
Now if the desired V
(actual), then add the difference between V
(desired) – V
desired. This is your new V
applied to VXMON and the whole sequence should be
repeated again (see Figure 5).
C
Now if the V
(desired), perform the reset sequence as described in
the next section. The new V
to VXMON will now be: V
(actual) – V
Note: This operation does not corrupt the memory array.
Setting a Lower V
In order to set V
present value, then V
ing to the procedure described below. Once V
has been “reset”, then V
voltage using the procedure described in “Setting a
Higher V
Resetting the V
To reset a V
age (Vp) to the WDO pin before a START condition is
set up on SDA. Next, issue on the SDA pin the Slave
Address A0h followed by the Byte Address 03h for
V
by 00h for the Data Byte in order to reset V
STOP bit following a valid write operation initiates the
programming sequence. Pin WDO must then be
brought LOW to complete the operation.
After being reset, the value of V
nal value of 1.7V or lesser.
Notes: 1.This operation does not corrupt the memory
array.
TRIP1
ASE
ASE
TRIP2
TRIPX
A
B
, 0Bh for V
2. Set V
setting V
TRIPx
, and 0Dh for V
(actual).
TRIPX
TRIPx
TRIPX
Voltage”.
TRIPX
CC
TRIPx
TRIP2
(desired)).
voltage, apply the programming volt-
TRIP2
TRIPx
TRIPx
≅ 1.5(V2MON or V3MON), when
TRIPx
(actual), is higher than the V
TRIPX
TRIPx
(actual) to the original V
or V
Voltage
TRIPX
, and 0Fh for V
. The STOP bit following a valid
TRIPx
Voltage (x=1, 2, 3)
to a lower voltage than the
TRIP3
TRIP3
must first be “reset” accord-
is greater than the V
TRIPX
TRIPX
has been set, set VXMON
can be set to the desired
, and a 00h Data Byte in
TRIPX
TRIPx
respectively
TRIPX
voltage to be applied
(desired) – (V
becomes a nomi-
that should be
(that was previ-
TRIP3
TRIPx
TRIP1
, followed
May 25, 2006
FN8114.1
TRIPX
TRIPX
TRIPX
TRIPX
TRIPX
. The
, 09h
TRIPx