TDA7056A Datasheet, PDF (4/9 Pages) NXP Semiconductors – 3 W BTL mono audio output amplifier with DC volume control

Philips Semiconductors
3 W BTL mono audio output amplifier with
DC volume control
Product specificiation
TDA7056A
FUNCTIONAL DESCRIPTION
The TDA7056A is a mono BTL output amplifier with DC
volume control, designed for use in TV and monitor but
also suitable for battery-fed portable recorders and radios.
In conventional DC volume circuits the control or input
stage is AC coupled to the output stage via external
capacitor to keep the offset voltage low.
In the TDA7056A the DC volume stage is integrated into
the input stage so that coupling capacitors are not required
and a low offset voltage is maintained.
At the same time the minimum supply voltage remains low.
The BTL principle offers the following advantages:
• lower peak value of the supply current
• the frequency of the ripple on the supply voltage is twice
the signal frequency
Thus, a reduced power supply and smaller capacitors can
be used which results in cost savings.
For portable applications there is a trend to decrease the
supply voltage, resulting in a reduction of output power at
conventional output stages. Using the BTL principle
increases the output power.
The maximum gain of the amplifier is fixed at 35.5 dB. The
DC volume control stage has a logarithmic control
characteristic.
The total gain can be controlled from 35.5 dB to −44 dB.
If the DC volume control voltage is below 0.3 V, the device
switches to the mute mode.
The amplifier is short-circuit proof to ground, V_P and
across the load. A thermal protection circuit is also
implemented. If the crystal temperature rises above
+150 °C the gain will be reduced, thereby reducing the
output power.
Special attention is given to switch-on and off clicks, low
HF radiation and a good overall stability.
LIMITING VALUES
In accordance with the Absolute Maximum System (IEC 134).
SYMBOL
PARAMETER
CONDITIONS
V_P
I_ORM
I_OSM
P_tot
T_amb
T_stg
T_vj
T_sc
V₃
V₅
supply voltage range
repetitive peak output current
non repetitive peak output current
total power dissipation
operating ambient temperature range
storage temperature range
virtual junction temperature
short-circuit time
input voltage pin 3
input voltage pin 5
T_case < 60 °C
MIN.
−
−
−
−
−40
−55
−
−
−
−
MAX.
18
1.25
1.5
9
+85
+150
+150
1
8
8
UNIT
V
A
A
W
°C
°C
°C
hr
V
V
THERMAL RESISTANCE
SYMBOL
R_{th j-a}
R_{th j-c}
PARAMETER
from junction to ambient in free air
from junction to case
THERMAL RESISTANCE
55 K/W
10 K/W
Note to the thermal resistance
V_P = 12 V; R_L = 16 Ω; The maximum sine-wave dissipation is = 1.8 W. The R_{th vj-a} of the package is 55 K/W;
T_{amb (max)} = 150 − 55 x 1.8 = 51 °C
July 1994
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