TDA8944AJ Datasheet, PDF (7/20 Pages) NXP Semiconductors – 2 x 7 W BTL audio amplifier with DC gain control

Philips Semiconductors
TDA8944AJ
2 x 7 W BTL audio amplifier with DC gain control
8.6 Built-in protection circuits
The TDA8944AJ contains two types of protection circuits, i.e. short-circuit and
thermal shutdown.
8.6.1 Short-circuit protection
Short-circuit to ground or supply line — This is detected by a so-called ‘missing
current’ detection circuit which measures the current in the positive supply line and
the current in the ground line. A difference between both currents larger than 0.8 A,
switches the power stage to the standby mode; high impedance of the outputs and
very low supply current.
Short-circuit across the load — This is detected by an absolute-current
measurement. An absolute-current larger than 2 A, switches the power stage to
standby mode; high impedance of the outputs and a very low supply current.
8.6.2 Thermal shutdown protection
The junction temperature is measured by a temperature sensor; at a junction
temperature of approximately 150 °C this detection circuit switches the power stage
to the standby mode; high impedance of the outputs and very low supply current.
9. Limiting values
Table 5: Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
Conditions
V_CC
supply voltage
no signal
operating
V_I
I_ORM
T_stg
T_amb
P_tot
V_CC(sc)
input voltage
repetitive peak output current
storage temperature
non-operating
operating ambient temperature
total power dissipation
supply voltage to guarantee short-circuit
protection
10. Thermal characteristics
Min
Max
Unit
−0.3
+25
V
−0.3
+18
V
−0.3
V_CC + 0.3
V
-
2
A
−55
+150
°C
−40
+85
°C
-
18
W
-
15
V
Table 6:
Symbol
R_th(j-a)
R_th(j-mb)
Thermal characteristics
Parameter
Conditions
thermal resistance from junction to ambient
in free air
thermal resistance from junction to mounting base both channels driven
Value Unit
40
K/W
4.5
K/W
9397 750 09433
Product data
Rev. 01 — 01 March 2002
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
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