X9520 Datasheet, PDF (18/33 Pages) Intersil Corporation – Triple DCP, POR,2kbit EEPROM Memory, Dual Voltage Monitors

X9520
(See Figure 23). The user does not have to set the
WEL bit in the CONSTAT register before performing
this write sequence.
Setting a Lower V_TRIPx Voltage (x=1,2,3).
In order to set V_TRIPx to a lower voltage than the
present value, then V_TRIPx must first be “reset”
according to the procedure described below. Once
V_TRIPx has been “reset”, then V_TRIPx can be set to
the desired voltage using the procedure described in
“Setting a Higher V_TRIPx Voltage”.
Resetting the V_TRIPx Voltage (x=1,2,3).
To reset a V_TRIPx voltage, apply the programming
voltage (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 for
V_TRIP1, 0Bh for V_TRIP2, and 0Fh for V_TRIP3, followed
by 00h for the Data Byte in order to reset V_TRIPx. The
STOP bit following a valid write operation initiates the
programming sequence. Pin WP must then be brought
LOW to complete the operation (See Figure 23).The
user does not have to set the WEL bit in the CON-
STAT register before performing this write sequence.
After being reset, the value of V_TRIPx becomes a nom-
inal value of 1.7V.
V_TRIPx Accuracy (x=1,2,3).
The accuracy with which the V_TRIPx thresholds are set,
can be controlled using the iterative process shown in
Figure 24.
If the desired threshold is less that the present threshold
voltage, then it must first be “reset” (See "Resetting the
VTRIPx Voltage (x=1,2,3).").
The desired threshold voltage is then applied to the
appropriate input pin (V1 / Vcc, V2 or V3) and the pro-
cedure described in Section “Setting a Higher V_TRIPx
Voltage“ must be followed.
Once the desired V_TRIPx threshold has been set, the
error between the desired and (new) actual set threshold
can be determined. This is achieved by applying V1 / Vcc
to the device, and then applying a test voltage higher
than the desired threshold voltage, to the input pin of the
voltage monitor circuit whose V_TRIPx was programmed.
For example, if V_TRIP2 was set to a desired level of 3.0
V, then a test voltage of 3.4 V may be applied to the volt-
age monitor input pin V2. In the case of setting of V_TRIP1
then only V1 / Vcc need be applied. In all cases, care
should be taken not to exceed the maximum input volt-
age limits.
After applying the test voltage to the voltage monitor
input pin, the test voltage can be decreased (either in dis-
crete steps, or continuously) until the output of the volt-
age monitor circuit changes state. At this point, the error
between the actual / measured, and desired threshold
levels is calculated.
For example, the desired threshold for V_TRIP2 is set to
3.0 V, and a test voltage of 3.4 V was applied to the input
pin V2 (after applying power to V1 / Vcc). The input volt-
age is decreased, and found to trip the associated output
level of pin V2RO from a LOW to a HIGH, when V2
reaches 3.09 V. From this, it can be calculated that the
programming error is 3.09 - 3.0 = 0.09 V.
V_P
WP
SCL
SDA
0 1 23 4 56 7
0 1 23 4 56 7
0 1 23 4 56 7
00h ^†
A0h^†
03h^† Resets VTRIP1
Data Byte
S
T
0Bh^† Resets VTRIP2
A
R
0Fh^† Resets VTRIP3
T
† _{All others Reserved.}
Figure 23. Resetting the V_TRIPx Level
18
FN8206.0
March 8, 2005