Functional description, Limiting values – Philips TDA7052AT User Manual
Page 4
July 1994
4
Philips Semiconductors
Product specification
1 W BTL mono audio amplifier with DC
volume control
TDA7052A/AT
FUNCTIONAL DESCRIPTION
The TDA7052A/AT are mono BTL output amplifiers with
DC volume control, designed for use in TV and monitors
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
capacitors to keep the offset voltage low.
In the TDA7052A/AT the DC volume control stage is
integrated into the input stage so that no coupling
capacitors are required and yet a low offset voltage is
maintained. At the same time the minimum supply 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 with 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. Also a thermal protection circuit is
implemented. If the crystal temperature rises above
+150
°
C the gain will be reduced, so the output power is
reduced.
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
MIN.
MAX.
UNIT
V
P
supply voltage range
−
18
V
I
ORM
repetitive peak output current
−
1.25
A
I
OSM
non-repetitive peak output current
−
1.5
A
P
tot
total power dissipation
T
amb
≤
25%
TDA7052A
−
1.25
W
TDA7052AT
−
0.8
W
T
amb
operating ambient temperature range
−
40
+85
°
C
T
stg
storage temperature range
−
55
+150
°
C
T
vj
virtual junction temperature
−
+150
°
C
T
sc
short-circuit time
−
1
hr
V
2
input voltage pin 2
−
8
V
V
4
input voltage pin 4
−
8
V