AS8412 View Datasheet(PDF) - austriamicrosystems AG
Part Name
Description
Manufacturer
AS8412 Datasheet PDF : 14 Pages
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High Performance Automotive Sonar Intrusion – Data Sheet
AS8412
Low Level Output Voltage Vol
High Level Output Voltage Voh
High-Z Output Current
Ioz
Total Supply Current
Idd
-
0.5
-
0.5
-
0.5
4.0 -
-
-
-
10
-
0.65 1.0
-
1.0
1.6
V
Pins 1, 20
Iol=3 mA
V
Pins 18, 19 Iol=4 mA
V
Pins 17
Iol=12mA
V
Pins 1, 20
Ioh=-3 mA
µA
Pins 17, 18, Vo=5V
19
mA SEL40K= 1 crystal or clock
mA SEL40K= 0 ceramic resonator
C1=C2=100pF
A.C. Electrical Characteristics
(VDD = 5 V, VSS = Ground, TA = 25°C)
Parameter
Symbol Min Typ
Power-on-reset width
tpor
50
-
500
-
500
-
Self-test delay (incl. tpor)
tstd
1.3
-
1.7
-
1.7
-
Fault indication pulse width
tstw
4.3
-
ALARM low pulse width
tal
200
-
LED low pulse width
tonn
-
89
-
977
LED high pulse width
toff
-
888
Max
70
530
800
1.4
1.9
2.1
4.6
-
-
-
-
Units Conditions
SEL40K= 0, resonator / clock
ms SEL40K= 1, clock
SEL40K= 1, crystal
s SEL40K= 0, resonator / clock
SEL40K= 1, clock
SEL40K= 1, crystal
s
ms Pins 18, 19
ms narrow = no detection
ms wide = detection
ms
System Description
Ultrasonic intrusion detectors are very popular in vehicle security systems, due to their low
cost, good area coverage and easiness of installation. The AS8412 uses the sonar principle to
build a high-performance intrusion detector that follows the requirements of the OEM automo-
tive industry. As very short ultrasonic bursts are sent, the power needed to drive the transmitter
is reduced. Interference and signal cancellation effects, present in systems with continuous
transmission, are virtually eliminated.
Fig. 1 shows the pulse/echo timing generated by the AS8412.
The basic concept behind the AS8412 is the detection of changes in the relative position of
objects inside the vehicle, by monitoring successive echo patterns with a discriminator based
on fuzzy-logic.
Despite the higher complexity of this approach, that demands both analog and digital signal
processing, the solution is made cost-effective with the use of a single IC and a small number
of external components.
March 2001
Page 5 of 14
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