X1227
Figure 4. Power On Reset and Low Voltage Reset
V
TRIP
V
CC
t
t
PURST
PURST
t
RPD
t
F
t
R
RESET
V
RVALID
V
THRESHOLD RESET PROCEDURE
Setting the V
Voltage
CC
TRIP
[OPTIONAL]
It is necessary to reset the trip point before setting the
new value.
The X1227 is shipped with a standard V
threshold
CC
(V
) voltage. This value will not change over normal
TRIP
To set the new V
threshold voltage to the V pin and tie the RESET pin
to the programming voltage V . Then write data 00h to
address 01h. The stop bit following a valid write opera-
voltage, apply the desired V
TRIP
TRIP
operating and storage conditions. However, in applica-
tions where the standard V is not exactly right, or if
higher precision is needed in the V
X1227 threshold may be adjusted. The procedure is
described below, and uses the application of a nonvol-
atile write control signal.
CC
TRIP
P
value, the
TRIP
tion initiates the V
programming sequence. Bring
TRIP
RESET to V
to complete the operation. Note: this
CC
operation may take up to 10 milliseconds to complete
and also writes 00h to address 01h of the EEPROM
array.
Figure 5. Set V
Level Sequence (V = desired V
value)
TRIP
CC
TRIP
V
= 15V
P
RESET
V
CC
V
CC
0
1
2
3
4
5 6 7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5 6 7
SCL
SDA
AEh
00h
01h
00h
Note: BP0, BP1, BP2 must be disabled.
Resetting the V
Voltage
to 10 milliseconds to complete and also writes 00h to
address 03h of the EEPROM array.
TRIP
This procedure is used to set the V
to a “native”
TRIP
voltage level. For example, if the current V
is 4.4V
TRIP
For best accuracy in setting V
following sequence be used.
, it is advised that the
TRIP
and the new V
must be 4.0V, then the V
must
TRIP
TRIP
be reset. When V
is reset, the new V
is some-
TRIP
TRIP
1.Program V
as above.
thing less than 1.7V. This procedure must be used to
set the voltage to a lower value.
TRIP
2.Measure resulting V
by measuring the V
CC
TRIP
value where a RESET occurs. Calculate Delta =
(Desired – Measured) V value.
To reset the new V
voltage, apply more than 5.5V
TRIP
TRIP
to the V
pin and tie the RESET pin to the
CC
programming voltage V . Then write 00h to address
3.Perform a V
program using the following formula
P
TRIP
03h. The stop bit of a valid write operation initiates the
to set the voltage of the RESET pin:
V
programming sequence. Bring RESET to V
to
TRIP
CC
V
= (Desired Value – Delta) + 0.025V
RESET
complete the operation. Note: this operation takes up
Characteristics subject to change without notice. 9 of 28
REV 1.1.20 1/13/03
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