TDA8948J_1
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 01 — 27 February 2008
8 of 26
NXP Semiconductors
TDA8948J
4-channel audio amplifier
8.5 Built-in protection circuits
The TDA8948J contains two types of detection sensors: one measures local temperatures
of the power stages and one measures the global chip temperature. At a local
temperature of approximately 185
°
C or a global temperature of approximately 150
°
C,
this detection circuit switches off the power stages for 2 ms. High-impedance of the
outputs is the result. After this time period the power stages switch on automatically and
the detection will take place again; still a too high temperature switches off the power
stages immediately. This protects the TDA8948J against shorts to ground, to the supply
voltage and across the load, and against too high chip temperatures.
The protection will only be activated when necessary, so even during a short-circuit
condition, a certain amount of (pulsed) current will still be flowing through the short, just as
much as the power stage can handle without exceeding the critical temperature level.
9.
Limiting values
[1]
The amplifier can deliver output power with non-clipping output signals into nominal loads as long as the
ratings of the IC are not exceeded.
10. Thermal characteristics
Table 6.
Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
Conditions
Min
Max
Unit
V
CC
supply voltage
operating
−
0.3
+26
V
no (clipping) signal
[1]
−
0.3
+28
V
V
I
input voltage
-
−
0.3
V
CC
+ 0.3
V
I
ORM
repetitive peak output
current
-
-
4
A
T
stg
storage temperature
non-operating
−
55
+150
°
C
T
amb
ambient temperature
-
−
40
+85
°
C
P
tot
total power dissipation
-
-
69
W
V
CC(sc)
supply voltage (short circuit) -
-
24
V
Table 7.
Thermal characteristics
Symbol
Parameter
Conditions
Typ
Unit
R
th(j-a)
thermal resistance from junction
to ambient
in free air
40
K/W
R
th(j-c)
thermal resistance from junction
to case
all channels driven
2
K/W
