X4043/45
Characteristics subject to change without notice.
4 of 25
REV 1.1.17 9/14/01
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Setting a V
There are two procedures used to set the threshold
voltages (V
TRIP
), depending if the threshold voltage to
be stored is higher or lower than the present value. For
example, if the present V
TRIP
V
TRIP
is 3.2 V, the new voltage can be stored directly
into the V
TRIP
cell. If however, the new setting is to be
lower than the present setting, then it is necessary to
“reset” the V
TRIP
voltage before setting the new value.
TRIP
Voltage
is 2.9 V and the new
Setting a Higher V
To set a V
higher than the present threshold, the user must apply
the desired V
TRIP
threshold voltage to the V
programming voltage (Vp) must be applied to the WP
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
Byte in order to program V
TRIP
a valid write operation initiates the programming
sequence. WP pin must then be brought LOW to com-
plete the operation.
TRIP
Voltage
TRIP
threshold to a new voltage which is
CC
. Then, a
TRIP
. The STOP bit following
and a 00h Data
To check if the V
the device. Slowly ramp up V
output, RESET (4043) or RESET (4045) switches. The
voltage at which this occurs is the V
Figure 2).
TRIP
has been set, first power down
and observe when the
CC
TRIP
(actual) (see
C
ASE
A
Now if the desired V
(actual), then add the difference between V
(desired) – V
TRIP
(actual) to the original V
This is your new V
TRIP
that should be applied to V
and the whole sequence should be repeated again
(see Figure 5).
TRIP
is greater than the V
TRIP
TRIP
TRIP
desired.
CC
C
ASE
B
Now if the V
(desired), perform the reset sequence as described in
the next section. The new V
to V
CC
will now be: V
TRIP
(desired) – (V
V
TRIP
(desired)).
Note:
This operation does not corrupt the memory
array.
TRIP
(actual), is higher than the V
TRIP
TRIP
voltage to be applied
TRIP
(actual) –
Setting a Lower V
In order to set V
present value, then V
ing to the procedure described below. Once V
been “reset”, then V
TRIP
age using the procedure described in “Setting a Higher
V
TRIP
Voltage”.
TRIP
Voltage
to a lower voltage than the
must first be “reset” accord-
TRIP
TRIP
TRIP
has
can be set to the desired volt-
Resetting the V
To reset a V
TRIP
voltage, apply the programming volt-
age (Vp) to the WP 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 fol-
lowed by 00h for the Data Byte in order to reset V
TRIP
.
The STOP bit following a valid write operation initiates
the programming sequence. Pin WP must then be
brought LOW to complete the operation.
TRIP
Voltage
After being reset, the value of V
TRIP
becomes a nomi-
nal value of 1.7V or lesser.
Note:
This operation does not corrupt the memory
array.