TDA8944J
2 x 7 W stereo Bridge Tied Load (BTL) audio amplifier
Rev. 02 — 14 February 2000
Product specification
1. General description
The TDA8944J is a dual-channel audio power amplifier with an output power of
2
×
7 W at an 8
Ω
load and a 12 V supply. The circuit contains two Bridge Tied Load
(BTL) amplifiers with an all-NPN output stage and standby/mute logic. The TDA8944J
comes in a 17-pin DIL-bent-SIL (DBS) power package. The TDA8944J is
printed-circuit board (PCB) compatible with all other types in the TDA894x family.
One PCB footprint accommodates both the mono and the stereo products.
2. Features
Few external components
Fixed gain
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.
c
c
3. Applications
Mains fed applications (e.g. TV sound)
PC audio
Portable audio.
4. Quick reference data
Table 1:
V
CC
I
q
I
stb
Quick reference data
Conditions
V
CC
= 12 V; R
L
=
∞
Min
6
-
-
Typ
12
24
-
Max
18
36
10
Unit
V
mA
μA
supply voltage
quiescent supply current
standby supply current
Symbol Parameter
NXP Semiconductors
TDA8944J
2 x 7 W stereo BTL audio amplifier
Quick reference data
…continued
Conditions
THD = 10%; R
L
= 8
Ω;
V
CC
= 12 V
P
o
= 1 W
Min
6
-
31
50
Typ
7
0.03
32
65
Max
-
0.1
33
-
Unit
W
%
dB
dB
output power
total harmonic distortion
voltage gain
supply voltage ripple
rejection
Table 1:
P
o
THD
G
v
SVRR
Symbol Parameter
5. Ordering information
Table 2:
Ordering information
Package
Name
TDA8944J
DBS17P
Description
plastic DIL-bent-SIL power package;
17 leads (lead length 12 mm)
Version
SOT243-1
Type number
6. Block diagram
width
VCC1
3
VCC2
16
1
IN1−
IN1+
8
6
4
OUT1−
OUT1+
TDA8944J
14
IN2−
IN2+
9
12
17
VCC
MODE
SVR
10
11
20
kΩ
2
GND1
STANDBY/
MUTE LOGIC
20
kΩ
OUT2+
OUT2−
SHORT CIRCUIT
AND
TEMPERATURE
PROTECTION
15
MBK933
GND2
Fig 1. Block diagram.
9397 750 06861
© NXP B.V. 2010. All rights reserved.
Product specification
Rev. 02 — 14 February 2000
2 of 22
NXP Semiconductors
TDA8944J
2 x 7 W stereo BTL audio amplifier
7. Pinning information
7.1 Pinning
handbook, halfpage
OUT1− 1
GND1 2
VCC1 3
OUT1+ 4
n.c. 5
IN1+ 6
n.c. 7
IN1− 8
IN2− 9
MODE 10
SVR 11
IN2+ 12
n.c. 13
OUT2− 14
GND2 15
VCC2 16
OUT2+ 17
MBK936
TDA8944J
Fig 2. Pin configuration.
7.2 Pin description
Table 3:
Symbol
OUT1−
GND1
V
CC1
OUT1+
n.c.
IN1+
n.c.
IN1−
IN2−
MODE
SVR
IN2+
9397 750 06861
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
not connected
negative input 1
negative input 2
mode selection input (standby, mute, operating)
half supply voltage decoupling (ripple rejection)
positive input 2
© NXP B.V. 2010. All rights reserved.
Product specification
Rev. 02 — 14 February 2000
3 of 22
NXP Semiconductors
TDA8944J
2 x 7 W stereo BTL audio amplifier
Pin description
…continued
Pin
13
14
15
16
17
Description
not connected
negative loudspeaker terminal 2
ground channel 2
supply voltage channel 2
positive loudspeaker terminal 2
Table 3:
Symbol
n.c.
OUT2−
GND2
V
CC2
OUT2+
8. Functional description
The TDA8944J is a stereo BTL audio power amplifier capable of delivering 2
×
7 W
output power to an 8
Ω
load at THD = 10%, using a 12 V power supply and an
external heatsink. The voltage gain is fixed at 32 dB.
With the three-level MODE input the device can be switched from ‘standby’ to ‘mute’
and to ‘operating’ mode.
The TDA8944J outputs are protected by an internal thermal shutdown protection
mechanism and a short-circuit protection.
8.1 Input configuration
The TDA8944J inputs can be driven symmetrical (floating) as well as asymmetrical.
In the asymmetrical mode one input pin is connected via a capacitor to the signal
ground which 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.
The input cut-off frequency is:
1
f
i
(
cut
–
off
)
=
-----------------------------
-
2
–
(
R
i
×
C
i
)
For R
i
= 45 kΩ and C
i
= 220 nF:
1
f
i
(
cut
–
off
)
=
------------------------------------------------------------------
=
16
Hz
-
3
–
9
2
–
(
45
×
10
×
220
×
10
)
As shown in
Equation 1
and
2,
large capacitor 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 HF oscillations do not leave the inputs open, connect a capacitor
of at least 1.5 nF across the input pins close to the device.
(2)
(1)
9397 750 06861
© NXP B.V. 2010. All rights reserved.
Product specification
Rev. 02 — 14 February 2000
4 of 22
NXP Semiconductors
TDA8944J
2 x 7 W stereo BTL audio amplifier
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:
•
•
•
•
8.2.1
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.
Output power measurement
The output power as a function of the supply voltage is measured on the output pins
at THD = 10%; see
Figure 8.
The maximum output power is limited by the maximum
supply voltage of 12 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
= 12 V, R
L
= 8
Ω
and P
o
= 4 W at THD = 0.1% (see
Figure 6),
the
Average Listening Level (ALL) – music power – without any distortion yields:
P
o(ALL)
= 4 W/15.85 = 252 mW.
The power dissipation can be derived from
Figure 11 on page 10
for 0 dB
respectively 12 dB headroom.
Table 4:
0 dB
12 dB
Power rating as function of headroom
Power output (THD = 0.1%)
P
o
= 4 W
P
o(ALL)
= 252 mW
Power dissipation (P)
8W
4W
Headroom
For the average listening level a power dissipation of 4 W can be used for a heatsink
calculation.
8.3 Mode selection
The TDA8944J has three functional modes, which can be selected by applying the
proper DC voltage to pin MODE. See
Figure 4
and
5
for the respective DC levels,
which depend on the supply voltage level. The MODE pin can be driven by a 3-state
logic output stage: e.g. a microcontroller with additional components for DC-level
shifting.
Standby —
In this mode the current consumption is very low and the outputs are
floating. The device is in standby mode when (V
CC
−
0.5 V) < V
MODE
< V
CC
, or when
the MODE pin is left floating (high impedance). The power consumption of the
TDA8944J will be reduced to <0.18 mW.
9397 750 06861
© NXP B.V. 2010. All rights reserved.
Product specification
Rev. 02 — 14 February 2000
5 of 22
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