TEA3718DP datasheet(9/16 Pages) STMICROELECTRONICS

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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 - RC) is fed to

the comparator input pin (Fig. A)

Depending of the RCC value the behaviour of

the circuit is different on alarm condition:

1) RC >80

Ω ⇒ the output stage is switched off

2) RC >60

Ω ⇒ the current in the motor windings

is reduced according to the approximate formula:

(see also fig. E and F)

with VTH = Threshold of the comparator (VCH,

VCM,VCL) R = 700

Ω (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)

VTH

−

VCC

+ RC •

Figure C: Alarm Detection for Powerdip Package

Figure D: CommonDetection for Several Multiwatt Package

TEA3718-TEA3718S

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