TDA8946AJ
2 x 15 W BTL audio amplifier with DC gain control
Rev. 01 — 01 March 2002
M3D541
Product data
1. General description
The TDA8946AJ is a dual-channel audio power amplifier with DC gain control. It has
an output power of 2
×
15 W at an 8
Ω
load and an 18 V supply. The circuit contains
two Bridge-Tied Load (BTL) amplifiers with an all-NPN output stage and
standby/mute logic. The overall gain can be adjusted from +30 dB down to
−50
dB
using a DC control voltage. This feature can be used for volume control or for a preset
gain. The TDA8946AJ comes in a 17-pin DIL-bent-SIL (DBS) power package and is
pin compatible with the TDA8946J.
2. Features
s
s
s
s
s
s
s
s
s
s
Gain/volume adjustment via a DC control pin
Soft clipping
Operating at a low supply voltage
Standby and mute mode
No on/off switching plops
Low standby current
High supply voltage ripple rejection
Outputs short-circuit protected to ground, supply and across the load
Thermally protected
Printed-circuit board compatible with TDA8944AJ and TDA8580J.
3. Applications
s
Mains fed applications (e.g. TV sound)
s
PC audio
s
Portable audio.
4. Quick reference data
Table 1:
V
CC
I
q
I
stb
P
o
THD
Quick reference data
Conditions
V
CC
= 18 V; R
L
=
∞
THD = 10%; R
L
= 8
Ω;
V
CC
= 18 V
P
o
= 1 W
Min
4.5
-
-
13
-
Typ
18
45
-
15
0.07
Max
18
55
10
-
0.5
Unit
V
mA
µA
W
%
supply voltage
quiescent supply current
standby supply current
output power
total harmonic distortion
Symbol Parameter
Philips Semiconductors
TDA8946AJ
2 x 15 W BTL audio amplifier with DC gain control
Quick reference data
…continued…continued
Conditions
Min
29
-
-
Typ
30
80
55
Max
31
-
-
Unit
dB
dB
dB
maximum voltage gain
voltage gain control range
supply voltage ripple
rejection
Table 1:
G
v(max)
G
v(cr)
SVRR
Symbol Parameter
5. Ordering information
Table 2:
Ordering information
Package
Name
TDA8946AJ
DBS17P
Description
Version
plastic DIL-bent-SIL power package; 17 leads (lead SOT243-1
length 12 mm)
Type number
6. Block diagram
idth
VCC1
3
VCC2
16
1
IN1
−
IN1
+
8
6
4
OUT1−
OUT1+
GC
13
TDA8946AJ
14
OUT2
−
IN2
−
IN2
+
9
12
17
VCC
OUT2
+
MODE
SVR
10
11
STANDBY/
MUTE LOGIC
20
kΩ
20
kΩ
7
SGND
2
GND1
SHORT CIRCUIT
AND
TEMPERATURE
PROTECTION
15
MGW608
GND2
Fig 1. Block diagram.
9397 750 09434
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
Product data
Rev. 01 — 01 March 2002
2 of 20
Philips Semiconductors
TDA8946AJ
2 x 15 W BTL audio amplifier with DC gain control
7. Pinning information
7.1 Pinning
handbook, halfpage
OUT1
−
GND1
VCC1
OUT1
+
n.c.
IN1
+
SGND
IN1
−
IN2
−
1
2
3
4
5
6
7
8
9
TDA8946AJ
MODE 10
SVR 11
IN2
+
12
GC 13
OUT2
−
14
GND2 15
VCC2 16
OUT2
+
17
MGW609
Fig 2. Pin configuration.
7.2 Pin description
Table 3:
Symbol
OUT1−
GND1
V
CC1
OUT1+
n.c.
IN1+
SGND
IN1−
IN2−
MODE
SVR
IN2+
9397 750 09434
Pin description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
Description
negative loudspeaker terminal 1
ground channel 1
supply voltage channel 1
positive loudspeaker terminal 1
not connected
positive input 1
signal ground
negative input 1
negative input 2
mode selection input (standby, mute, operating)
half supply voltage decoupling (ripple rejection)
positive input 2
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
Product data
Rev. 01 — 01 March 2002
3 of 20
Philips Semiconductors
TDA8946AJ
2 x 15 W BTL audio amplifier with DC gain control
Pin description
…continued…continued
Pin
13
14
15
16
17
Description
DC gain control
negative loudspeaker terminal 2
ground channel 2
supply voltage channel 2
positive loudspeaker terminal 2
Table 3:
Symbol
GC
OUT2−
GND2
V
CC2
OUT2+
8. Functional description
The TDA8946AJ is a stereo BTL audio power amplifier capable of delivering 2
×
15 W
output power to an 8
Ω
load at THD = 10%, using a 18 V power supply and an
external heatsink. The gain of both amplifiers can be adjusted using a DC control
voltage (pin GC). This feature can be used for volume control or a preset gain.
With the three-level MODE input the device can be switched from ‘standby’ to ‘mute’
and to ‘operating’ mode.
The TDA8946AJ outputs are protected by an internal thermal shutdown protection
mechanism and a short-circuit protection.
8.1 Input configuration
The TDA8946AJ inputs can be driven symmetrical (floating) as well as asymmetrical.
In the asymmetrical mode (see
Figure 3)
one input pin is connected via a capacitor to
the signal source and the other input is connected to the signal ground. The signal
ground should be as close as possible to the SVR (electrolytic) capacitor ground.
Note that the DC level of the input pins is half of the supply voltage V
CC
, so coupling
capacitors for both pins are necessary.
handbook, halfpage
VCC
IN
+
IN
−
SVR
signal
ground
power
ground
signal
source
MGW610
Fig 3. Asymmetrical input configuration.
9397 750 09434
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
Product data
Rev. 01 — 01 March 2002
4 of 20
Philips Semiconductors
TDA8946AJ
2 x 15 W BTL audio amplifier with DC gain control
The input cut-off frequency is:
1
f
i
(
cut
–
off
)
=
------------------------------------------
2π
(
0.5
×
R
i
×
C
i
)
For R
i
= 32 kΩ and C
i
= 220 nF:
1
f
i
(
cut
–
off
)
=
------------------------------------------------------------------------------
=
45.2
Hz
3
–
9
2π
(
0.5
×
32
×
10
×
220
×
10
)
(1)
(2)
As shown in
Equation 2,
large capacitors values for the inputs are not necessary; so
the switch-on delay during charging of the input capacitors can be minimized. This
results in a good low frequency response and good switch-on behaviour.
Remark:
To prevent high frequency oscillations do not leave the inputs open, connect
a capacitor of 4.7 nF across the input pins close to the device (see
Figure 15).
8.2 Power amplifier
The power amplifier is a Bridge-Tied Load (BTL) amplifier with an all-NPN output
stage, capable of delivering a peak output current of 2 A.
The BTL principle offers the following advantages:
•
•
•
•
Lower peak value of the supply current
The ripple frequency on the supply voltage is twice the signal frequency
No expensive DC-blocking capacitor
Good low frequency performance.
8.2.1 Output power measurement
The output power as a function of the supply voltage is measured on the output pins
at THD = 10%; see
Figure 10.
The maximum output power is limited by the supply
voltage of 18 V and the maximum available output current: 2 A repetitive peak
current.
8.2.2 Headroom
Typical CD music requires at least 12 dB (factor 15.85) dynamic headroom -
compared to the average power output - for transferring the loudest parts without
distortion. At V
CC
= 18 V, R
L
= 8
Ω
and P
o
= 10 W at THD = 0.5% (see
Figure 8),
the
Average Listening Level (ALL) - music power - without any distortion yields:
10
W
P
o
(
ALL
)
=
-------------
=
631
mW
15.85
The power dissipation can be derived from
Figure 12 on page 11
for 0 dB
respectively 12 dB headroom.
(3)
9397 750 09434
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
Product data
Rev. 01 — 01 March 2002
5 of 20
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