X40420 XICOR [Xicor Inc.], X40420 Datasheet - Page 5

• Manufacturer Part Number: X40420
• Description: Dual Voltage Monitor with Integrated CPU Supervisor and System Battery Switch
• Manufacturer: XICOR [Xicor Inc.]

X40420/X40421 – Preliminary
Figure 3. V
Figure 4. Watchdog Restart
V1 AND V2 THRESHOLD PROGRAM PROCEDURE
(OPTIONAL)
The X40420/21 is shipped with standard V1 and V2
threshold (V
change over normal operating and storage conditions.
However, in applications where the standard thresholds
are not exactly right, or if higher precision is needed in the
threshold value, the X40420 trip points may be adjusted.
The procedure is described below, and uses the applica-
tion of a high voltage control signal.
Setting a V
There are two procedures used to set the threshold volt-
ages (V
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
than the present threshold, the user must apply the
desired V
input pin (Vcc(V1MON) or V2MON). Then, a program-
ming 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, followed by the Byte
Address 01h for V
REV 1.2.14 7/12/02
TRIPx
SCL
SDA
is 3.2 V, the new voltage can be stored directly
TRIPx
TRIPx
TRIPx
TRIPx
WDO
SCL
SDA
TRIPx
TRIPX
TRIPx
TRIP1,
.6µs
), depending if the threshold voltage to be
Start
threshold to a new voltage which is higher
cell. If however, the new setting is to be
threshold voltage to the corresponding
Voltage (x=1, 2)
voltage before setting the new value.
Set/Reset Conditions
V
TRIP1
TRIPx
TRIP2
, and 09h for V
Voltage (x=1, 2)
) voltages. These values will not
0
A0h
V
TRIPx
1.3µs
TRIPX
WDT Reset
is 2.9 V and the new
(X = 1, 2)
TRIP2
7
Stop
0
, and a 00h
www.xicor.com
V
CC
/V2MON
7
Data Byte in order to program V
following a valid write operation initiates the programming
sequence. Pin WDO must then be brought LOW to
complete the operation.
To check if the V
value slightly greater than V
set). Slowly ramp down VXMON and observe when the
corresponding outputs (LOWLINE and V2FAIL) 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
This is your new V
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
VXMON will now be: V
– V
Note: 1. This operation does not corrupt the memory
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
ASE
ASE
V
TRIPX
P
0
A
B
2. Set V
00h
array.
grammed
TRIPx
(desired)).
TRIPX
TRIPX
Voltage”.
CC
TRIPX
7
Characteristics subject to change without notice.
(actual) to the original V
TRIPx
= 5V, when V
TRIPx
(actual), is higher than the V
TRIPX
TRIPX
TRIPx
TRIPX
has been set, set VXMON to a
TRIPx
TRIPX
Voltage (x=1, 2)
to a lower voltage than the
t
must first be “reset” accord-
WC
that should be applied to
is greater than the V
(desired) – (V
TRIPX
can be set to the desired
voltage to be applied to
TRIPx
TRIP2
(that was previously
TRIPX
. The STOP bit
TRIPX
is being pro-
TRIPX
(actual).
desired.
(actual)
5 of 25
TRIPX
TRIPX
TRIPX
TRIPx