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2004 Jan 27
7
Philips Semiconductors
Preliminary specification
High efficiency 2
×
25 W/4
stereo car radio power amplifier
TDA1564
loudspeaker, the output stage will be repeatedly switched
on and off. The duty cycle in the ‘on’ condition is low
enough to prevent excessive dissipation.
The device also has two independent DC offset detection
circuits that can detect DC output voltages across the
speakers. With a DC offset greater than 2 V, a warning is
given on the diagnostic pin. There will be no internal
shutdown with DC offsets.
When the supply voltage drops below 6 V (e.g. engine
start), the circuit mutes immediately, avoiding clicks from
the electronic circuit preceding the power amplifier.
The voltage of the SE electrolytic capacitor (pin 4) is kept
at 0.5V
P
by means of a voltage buffer (see Fig.2). The
value of this capacitor has an important influence on the
output power in SE mode, especially at low signal
frequencies. A high value is recommended to minimize
dissipation at low frequencies.
The diagnostic output is an open-collector output and
requires a pull-up resistor. It gives the following outputs:
Clip detection at THD = 2.5 %
Short-circuit protection:
– When a short-circuit occurs (for at least 10 ms) at the
outputs to ground or the supply voltage, the output
stages are switched off to prevent excessive
dissipation; the outputs are switched on again
approximately 500 ms after the short-circuit is
removed, during this short-circuit condition the
protection pin is LOW
– When a short-circuit occurs across the load (for at
least 10 ms), the output stages are switched off for
approximately 500 ms; after this time, a check is
made to see whether the short-circuit is still present
– The power dissipation in any short-circuit condition is
very low.
During start-up/shutdown, when the product is internally
muted
Temperature prewarning:
– A prewarning (junction temperature > 145
°
C)
indicates that the temperature protection will become
active. The prewarning can be used to reduce the
input signal and thus reduce the power dissipation.
Offset detection:
– One of the channels has a DC output voltage greater
than 2 V.
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 60134).
THERMAL CHARACTERISTICS
Note
1.
The value of R
th(c-h)
depends on the application (see Fig.5).
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
V
P
supply voltage
operating
non-operating
load dump; t
r
>
2.5 ms
55
40
18
30
45
18
6
4
60
+150
150
+85
V
V
V
V
V
A
W
°
C
°
C
°
C
V
P(sc)
V
rp
I
ORM
P
tot
T
stg
T
vj
T
amb
short-circuit safe voltage
reverse polarity voltage
repetitive peak output current
total power dissipation
storage temperature
virtual junction temperature
ambient temperature
SYMBOL
PARAMETER
CONDITIONS
VALUE
UNIT
R
th(j-c)
R
th(j-a)
thermal resistance from junction to case
thermal resistance from junction to ambient
note 1
in free air
1.3
40
K/W
K/W