STM1403, STM1404
TAMPER DETECTION
Physical
Supply Voltage
The internally switched supply voltage, V
There are four (4) high-impedance physical
tamper detect input pins, 2 normally set to High
(NH) and 2 normally set to Low (NL). Each input is
designed with a glitch immunity. These inputs can
be connected externally to several types of actua-
tor devices (e.g., switches, wire mesh). A tamper
on any one of the four inputs that causes its state
to change will trigger the security alarm (SAL) and
drive it to active-low. Once the tamper condition no
longer exists, the SAL will return to its normal High
state.
(ei-
INT
ther V input or V
input) is continuously mon-
CC
BAT
itored. If V
should exceed the over voltage trip
INT
point, V (set at 4.2V, typical), or should go below
HV
the under voltage trip point, V (set at 2.0v, typi-
LV
cal). SAL will be driven active-low. Once the
tamper condition no longer exists, the SAL pin will
return to its normal High state.
Temperature (STM1404 Only)
The STM1404 has a built-in, bandgap-based sen-
sor to monitor the temperature. If a preset (cus-
tomer-selectable, factory-programmed) over-
TP and TP are set Normally to High (NH). They
1
3
are connected externally through a closed switch
or a high-impedance resistor to V (in the case
of STM1403/4A or STM1404A) or V
case of STM1403B/C, or STM1404B/C), A tamper
condition will be detected when the input pin is
temperature trip point (T ) or under-temperature
H
OUT
trip point (T ) is exceeded, the SAL is asserted
L
(in the
TPU
low.
When no tamper condition exists, SAL is normally
High (see PIN DESCRIPTIONS, page 9 of the full
datasheet for details).
When a tamper is detected, the SAL is activated
(driven low), independent of the part type. V
can be driven to one of three states, depending on
which variant of STM1403 or STM1404 is being
used (see Device Options, page 1):
pulled low. If not used, tie the pin to V
or V
.
TPU
OUT
TP and TP are set Normally to Low (NL). They
2
4
are connected externally through a high-imped-
ance resistor or a closed switch to V . A tamper
condition will be detected when the input pin is
pulled high. If not used, tie the pin to V
OUT
SS
.
SS
■
■
■
ON;
High-Z; or
Ground (V ).
SS
Note: The STM1403 or STM1404 must be initially
powered above V to enable the tamper detec-
RST
tion alarms. For example, if the battery is on while
V
V
= 0V, no alarm condition can be detected until
CC
CC
rises above V
(and t expires). From this
RST
rec
point on, alarms can be detected either on battery
or V . This is done to avoid false alarms when
CC
the device goes from no power to its operational
state.
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