Datasheet

ALARM OUTPUTS (TEA3718SP - TEA3718DP)
The alarm output becomes low when the junc-
tion temperature reaches T°C.
When an alarm condition occours, parts of the
supply voltage (dividing bridge R - R
C
) is fed to
the comparator input pin (Fig. A)
Depending of the R
C
C value the behaviour of
the circuit is different on alarm condition:
1) R
C
>80Ω⇒the output stage is switched off
2) R
C
>60Ω⇒the current in the motor windings
is reduced according to the approximate formula:
(see also fig. E and F)
with V
TH
= Threshold of the comparator (V
CH
,
V
CM
,V
CL
) R = 700Ω (typical)
For several Multiwatt packages a common de-
tection can be obtained as in Fig. D
PRE-ALARM OUTPUT
When the junction temperature reaches T1°C
(typ. = 170°C) a prealarm signal is generated.
Soft thermal protection occours when function
temperature reaches T2 (T2 > T1)
I
m
=
V
TH
R
S
−
V
CC
R + R
C
•
R
C
R
S
Figure C: Alarm Detection for Powerdip Package
Figure D: CommonDetection for Several Multiwatt Package
TEA3718-TEA3718S
9/16