1998 Oct 16
2
Philips Semiconductors
Product specification
Class-H high-output voltage level line
driver
TDA8574
FEATURES
Output voltage swing larger than supply voltage
High supply voltage ripple rejection
Low distortion
Low noise
ESD protected on all pins.
GENERAL DESCRIPTION
The TDA8574(T) is a two channel class-H high-output
voltage line driver for use in car audio applications.
The line driver behaves as a non-inverting amplifier with a
gain of 8 dB and a single-ended output. Due to the class-H
voltage lifting principle the voltage swing over the load is
more than the supply voltage. With a supply voltage of 9 V
the output voltage swing over the load will be
14 V (peak-to-peak).
The TDA8574 is available in a DIP16 package and the
TDA8574T in a SO16 package.
Line drivers are necessary in car audio systems in which
the power amplifiers are driven by long cables.
The signal-to-noise ratio of these car audio systems is
improved by using the TDA8574(T) class-H high-output
level line driver. The high-output level of TDA8574(T)
enables a reduction of the gain of the power amplifier
resulting in an improvement of the power amplifier
performance.
QUICK REFERENCE DATA
ORDERING INFORMATION
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
V
CC
supply voltage
6
9
12
V
I
CC
supply current
V
CC
= 9 V
-
8
13
mA
G
v
voltage gain
7.5
8
8.5
dB
V
o(rms)
maximal output voltage (RMS value)
THD = 0.1%
5.0
5.2
-
V
SVRR
supply voltage ripple rejection
50
65
-
dB
THD
total harmonic distortion
V
o(rms)
= 3 V; f = 1 kHz
-
0.003
-
%
V
no
noise output voltage
-
5
-
V
Z
o
output impedance
-
-
10
TYPE
NUMBER
PACKAGE
NAME
DESCRIPTION
VERSION
TDA8574T
SO16
plastic small outline package; 16 leads; body width 7.5 mm
SOT162-1
TDA8574
DIP16
plastic dual in-line package; 16 leads (300 mil)
SOT38-4
1998 Oct 16
4
Philips Semiconductors
Product specification
Class-H high-output voltage level line
driver
TDA8574
PINNING
SYMBOL
PIN
DESCRIPTION
V
CCL
1
supply voltage left channel
INL
2
input voltage left channel
SVRL
3
SVRR left channel
INML
4
inverting input left channel
INMR
5
inverting input right channel
SVRR
6
SVRR right channel
INR
7
input voltage right channel
V
CCR
8
supply voltage right channel
CR+
9
lift capacitor (+) right channel
CR
-
10
lift capacitor (
-
) right channel
RGND
11
ground right channel
OUTR
12
output voltage right channel
OUTL
13
output voltage left channel
LGND
14
ground left channel
CL
-
15
lift capacitor (
-
) left channel
CL+
16
lift capacitor (
+
) left channel
Fig.2 Pin configuration.
handbook, halfpage
TDA8574
TDA8574T
MGE667
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VCCL
INL
SVRL
INML
INMR
SVRR
INR
VCCR
CR
+
CR
-
RGND
OUTR
OUTL
LGND
CL
-
CL
+
FUNCTIONAL DESCRIPTION
Lift amplifier
The lift amplifier, referred to as LIFT AMP. in Fig.1, is used
as a non-inverting amplifier with a voltage gain of 8 dB set
by an internal feedback network. If the output voltage of
the signal amplifier is low, the external lift capacitor is
recharged by the lift amplifier. As soon as the output
voltage of the signal amplifier increases above 0.87
V
CC
the lift amplifier switches the voltage of the lift capacitor in
series with the supply voltage V
CC
. The voltage at the
positive side of the lift capacitor is referred to as lifted
supply voltage.
Signal amplifier
The signal amplifier, referred to as SIGNAL AMP. in Fig.1,
is used as a non-inverting amplifier. The voltage gain G
v
is
set by the feedback resistors according to the formula:
and should be set to 8 dB. The LIFT AMP. and SIG AMP.
must have equal voltage gain G
v
. The rail-to-rail output
stage of the signal amplifier uses the lifted supply voltage
to increase the output voltage swing.
G
v
1
R
2
R
1
-------
+
=
The DC output level is set to
0.87
V
CC.
The maximum
peak-to-peak output voltage of the signal amplifier is
calculated with the formula:
Buffers
The buffers prevent loading of the internal voltage divider
network made by a series connection of resistors. For a
good supply voltage ripple rejection this internal voltage
divider network has to be decoupled by an external
capacitor.
Reference
This circuit supplies all currents needed in the device.
V
o p
p
(
)
max
2
0.87V
CC
0.4
(
)
1998 Oct 16
5
Philips Semiconductors
Product specification
Class-H high-output voltage level line
driver
TDA8574
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
THERMAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
V
CC
supply voltage
operating
-
12
V
I
ORM
repetitive peak output current
-
20
mA
T
stg
storage temperature
-
55
+150
C
T
amb
operating ambient temperature
-
40
+85
C
T
j
junction temperature
-
+150
C
SYMBOL
PARAMETER
VALUE
UNIT
R
th j-a
thermal resistance from junction to ambient in free air
TDA8574 (DIP16)
75
K/W
TDA8574T (SO16)
110
K/W
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