Alarm output (TEA3718SP, TEA3718DP and TEA3718SDP)
The ALARM output pin becomes low when the junction temperature reaches T ° C. When an
alarm condition occurs, parts of the supply voltage (dividing bridge R - RC) is fed to the
comparator input pin (Figure 16). Depending on the RC value the behavior of the circuit on
an alarm condition is as follows:
● RC > 80 ohms, the output stage is switched off
● RC > 60 ohms, the current in the motor windings is reduced according to the
approximate formula: (see also Figure 18 and Figure 19)
R + RC
with VTH = threshold of the comparator (VCH, VCM, VCL) R = 700 ohms (typical).
For several Multiwatt packages a common detection can be obtained as in Figure 17.
Figure 16. Alarm detection for power DIP package