X1288V14T1 Intersil, X1288V14T1 Datasheet - Page 15

• Manufacturer Part Number: X1288V14T1
• Description: IC RTC/CAL/CPU SUP EE 14-TSSOP
• Manufacturer: Intersil
• Type: Clock/Calendar/Supervisor/EEPROMr

Specifications of X1288V14T1

• Memory Size: 256K (32K x 8)
• Time Format: HH:MM:SS:hh (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-TSSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LOW VOLTAGE RESET OPERATION
When a power failure occurs, and the voltage to the
part drops below a fixed v
issued to the host microcontroller. The circuitry moni-
tors the V
senses a preset threshold voltage. Power-up and
power-down waveforms are shown in Figure 5. The
Low Voltage Reset circuit is to be designed so the
RESET signal is valid down to 1.0V.
When the low voltage reset signal is active, the opera-
tion of any in progress nonvolatile write cycle is unaf-
fected, allowing a nonvolatile write to continue as long
as possible (down to the power-on reset voltage). The
low voltage reset signal, when active, terminates in
progress communications to the device and prevents
new commands, to reduce the likelihood of data cor-
ruption.
V
The X1288 is shipped with a standard V
(V
operating and storage conditions. However, in applica-
tions where the standard V
higher precision is needed in the V
X1288 threshold may be adjusted. The procedure is
described below, and uses the application of a nonvol-
atile write control signal.
Setting the V
It is necessary to reset the trip point before setting the
new value.
To set the new V
threshold voltage to the V
to the programming voltage V
address 01h. The stop bit following a valid write opera-
tion initiates the V
CC
TRIP
THRESHOLD RESET PROCEDURE [Optional]
) voltage. This value will not change over normal
RESET
CC
SDA
SCL
TRIP
line with a voltage comparator which
TRIP
Voltage
TRIP
voltage, apply the desired V
Start
programming sequence. Bring
CC
TRIP
15
TRIP
Note: All inputs are ignored during the active reset period (t
pin and tie the RESET pin
t
P
RSP
voltage, a reset pulse is
. Then write data 00h to
is not exactly right, or if
t
RSP
<t
WDO
Stop Start
FIGURE 4. WATCHDOG RESTART/TIME OUT
TRIP
CC
value, the
threshold
t
TRIP
RSP
>t
X1288
WDO
RESET to V
operation may take up to 10 milliseconds to complete
and also writes 00h to address 01h of the EEPROM
array.
Resetting the V
This procedure is used to set the V
voltage level. For example, if the current V
and the new V
be reset. When V
thing less than 1.7V. This procedure must be used to
set the voltage to a lower value.
To reset the new V
to the V
programming voltage V
03h. The stop bit of a valid write operation initiates the
V
complete the operation. Note: this operation takes up
to 10 milliseconds to complete and also writes 00h to
address 03h of the EEPROM array.
For best accuracy in setting V
the following sequence be used.
1.Program V
2.Measure resulting V
3.Perform a V
TRIP
value where a RESET occurs. Calculate Delta =
(Desired – Measured) V
to set the voltage of the RESET pin:
V
RESET
programming sequence. Bring RESET to V
t
RST
CC
= (Desired Value – Delta) + 0.025V
RST
CC
TRIP
TRIP
pin and tie the RESET pin to the
TRIP
).
to complete the operation. Note: this
TRIP
TRIP
as above.
t
RSP
program using the following formula
TRIP
must be 4.0V, then the V
Voltage
>t
TRIP
is reset, the new V
WDO
voltage, apply more than 5.5V
P
. Then write 00h to address
TRIP
by measuring the V
value.
TRIP
t
RST
, it is advised that
TRIP
TRIP
to a “native”
TRIP
TRIP
April 14, 2006
is some-
CC
is 4.4V
FN8102.3
CC
must
to