STM1404CSOBQ6F datasheet(11/35 Pages) STMICROELECTRONICS

11 / 35 page

STM1404

Pin descriptions

11/36

Pin descriptions

See Figure 1: Logic diagram and Table 2: Signal names for a brief overview of the signals

connected to this device.

2.1

SAL, security alarm output (open drain)

This signal can be generated when ANY of the following conditions occur:

●

VINT > VHV, where VHV = upper voltage trip limit (4.2 V typ); and where VINT = VCC or

VBAT;

●

VINT < VLV, where VLV = lower voltage trip limit (2.0 V typ); and where VINT = VCC or

VBAT; or

●

When any of the physical tamper inputs, TP1 to TP4, change from their normal states to

the opposite (i.e., intrusion of a physical enclosure).

●

TA > TH, where TH is an upper temperature trip limit specified by the customer (+80°C,

+85°C, and +95°C), factory-programmed (STM1404 only);

●

TA < TL, where TL is a lower temperature trip limit specified by the customer (–25°C or

–35°C), factory-programmed (STM1404 only);

Note:

The default state of the SAL output during initial power-up is undetermined.

The alarm function will operate either with VCC on or when the part is internally switched

from VCC to VBAT.

2.2

TP1, TP3

Physical tamper detect pin set normally to high (NH). They are connected externally through

a closed switch or a high-impedance resistor to VOUT (in the case of STM1404A) or VTPU (in

the case of STM1404B/C. A tamper condition will be detected when the input pin is pulled

low (see Figure 5 and Figure 6 on page 10). If not used, tie the pin to VOUT (for STM1404A)

or VTPU (for STM1404B/C).

2.3

TP2, TP4

Physical tamper detect pin set normally to low (NL). They are connected externally through

a high-impedance resistor or a closed switch to VSS. A tamper condition will be detected

when the input pin is pulled high (see Figure 7 and Figure 8 on page 10). If not used, tie the

pin to VSS.

2.3.1

Vccsw, VCC switch output

This output is low when VOUT (see Section 2.10: VOUT on page 13) is internally switched to

VCC; in this mode it may be used to turn on an external p-channel MOSFET switch which

can source an external device directly from VCC for currents greater than 80 mA (bypassing

the STM1404).

This pin goes high when VOUT is internally switched to VBAT and may be used as a

“BATTERY ON” indicator.

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