X40430 INTERSIL [Intersil Corporation], X40430 Datasheet - Page 5

• Manufacturer Part Number: X40430
• Description: Triple Voltage Monitor with Integrated CPU Supervisor
• Manufacturer: INTERSIL [Intersil Corporation]

Figure 3. V
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 X40430, X40431, X40434,
X40435 control register (also refer to page 20).
Figure 4. Watchdog Restart
V1, V2 AND V3 THRESHOLD PROGRAM
PROCEDURE (OPTIONAL)
The X40430 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 X40430,
X40431, X40434, X40435 trip points may be adjusted.
The procedure is described below, and uses the appli-
cation of a high voltage control signal.
SCL
SDA
WDO
SCL
SDA
TRIPX
Start
TRIP1,
.6µs
Set/Reset Conditions
0
A0h
V
V
TRIPX
TRIP2,
1.3µs
5
V
TRIP3
(X = 1, 2, 3)
WDT Reset
) voltages. These
7
X40430, X40431, X40434, X40435
0
Stop
V
CC
/V2MON/V3MON
7
V
Setting a V
There are two procedures used to set the threshold
voltages (V
to be stored is higher or lower than the present value.
For example, if the present V
new V
directly into the V
is to be lower than the present setting, then it is neces-
sary to “reset” the V
new value.
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 A0h, fol-
lowed by the Byte Address 01h for V
V
to program V
operation initiates the programming sequence. Pin WDO
must then be brought LOW to complete the operation. To
check if the V
slightly greater than V
Slowly ramp down VXMON and observe when the corre-
sponding outputs (LOWLINE, V2FAIL and V3FAIL)
switch. The voltage at which this occurs is the V
(actual).
P
0
TRIP2
00h
, and 0Dh for V
TRIPx
TRIPx
TRIPx
TRIPx
is 3.2 V, the new voltage can be stored
TRIPx
TRIPX
TRIPx
), depending if the threshold voltage
TRIPx
Voltage (x = 1, 2, 3)
threshold to a new voltage which is
. The STOP bit following a valid write
7
has been set, set VXMON to a value
TRIPx
TRIP3
threshold voltage to the corre-
TRIPx
TRIPX
cell. If however, the new setting
Voltage (x = 1, 2, 3)
, and a 00h Data Byte in order
voltage before setting the
t
WC
(that was previously set).
TRIPx
is 2.9 V and the
TRIP1
, 09h for
July 29, 2005
FN8251.0
TRIPX