TDA8942P
2 x 1.5 W stereo Bridge Tied Load (BTL) audio amplifier
Rev. 02 — 14 March 2000
Product specification
1. General description
The TDA8942P is a dual-channel audio power amplifier for an output power of
2
×
1.5 W at a 16
Ω
load and a 9 V supply. The circuit contains two Bridge Tied Load
(BTL) amplifiers with an all-NPN output stage and standby/mute logic.
The TDA8942P comes in a 16-pin dual in-line (DIP) package.The TDA8942P 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
s
s
s
s
s
s
s
s
s
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
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
Quick reference data
Conditions
V
CC
= 12 V; R
L
=
∞
Min
6
-
-
Typ
9
22
-
Max
18
32
10
Unit
V
mA
µA
supply voltage
quiescent supply current
standby supply current
Symbol Parameter
Philips Semiconductors
TDA8942P
2 x 1.5 W stereo BTL audio amplifier
Quick reference data
…continued
Conditions
THD = 10%; R
L
= 16
Ω;
V
CC
= 9 V
P
o
= 0.5 W
Min
1.2
-
31
50
Typ
1.5
0.03
32
65
Max
-
0.3
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
TDA8942P
DIP16
Description
plastic dual in-line package; 16 leads (300 mil);
long body
Version
SOT38-1
Type number
6. Block diagram
idth
VCC1
1
VCC2
9
15
IN1−
IN1+
13
3
2
OUT1−
OUT1+
TDA8942P
7
IN2−
IN2+
12
11
10
VCC
MODE
SVR
4
14
20
kΩ
16
GND1
STANDBY/
MUTE LOGIC
20
kΩ
OUT2+
OUT2−
SHORT CIRCUIT
AND
TEMPERATURE
PROTECTION
8
MGL578
GND2
Fig 1. Block diagram.
9397 750 06862
© Philips Electronics N.V. 2000. All rights reserved.
Product specification
Rev. 02 — 14 March 2000
2 of 23
Philips Semiconductors
TDA8942P
2 x 1.5 W stereo BTL audio amplifier
7. Pinning information
7.1 Pinning
handbook, halfpage
VCC1 1
OUT1+ 2
IN1+ 3
MODE 4
16 GND1
15 OUT1−
14 SVR
13 IN1−
TDA8942P
n.c. 5
n.c. 6
OUT2− 7
GND2 8
MGR895
12 IN2−
11 IN2+
10 OUT2+
9
VCC2
Fig 2. Pin configuration.
7.2 Pin description
Table 3:
Symbol
V
CC1
OUT1+
IN1+
MODE
n.c.
n.c.
OUT2−
GND2
V
CC2
OUT2+
IN2+
IN2−
IN1−
SVR
OUT1−
GND1
Pin description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Description
supply voltage channel 1
positive loudspeaker terminal 1
positive input 1
mode selection input (standby, mute, operating)
not connected
not connected
negative loudspeaker terminal 2
ground channel 2
supply voltage channel 2
positive loudspeaker terminal 2
positive input 2
negative input 2
negative input 1
half supply voltage decoupling (ripple rejection)
negative loudspeaker terminal 2
ground channel 1
9397 750 06862
© Philips Electronics N.V. 2000. All rights reserved.
Product specification
Rev. 02 — 14 March 2000
3 of 23
Philips Semiconductors
TDA8942P
2 x 1.5 W stereo BTL audio amplifier
8. Functional description
The TDA8942P is a stereo BTL audio power amplifier capable of delivering 2
×
1.5 W
output power to a 16
Ω
load at THD = 10%, using a 9 V power supply. 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 TDA8942P outputs are protected by an internal thermal shutdown protection
mechanism and a short-circuit protection.
8.1 Input configuration
The TDA8942P 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
)
=
----------------------------
-
2π
(
R
i
×
C
i
)
For R
i
= 45 kΩ and C
i
= 220 nF:
1
f
i
(
cut
–
off
)
=
----------------------------------------------------------------
=
16
Hz
-
3
–
9
2π
(
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)
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© Philips Electronics N.V. 2000. All rights reserved.
Product specification
Rev. 02 — 14 March 2000
4 of 23
Philips Semiconductors
TDA8942P
2 x 1.5 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:
•
•
•
•
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 8.
The maximum output power is limited by the maximum
power dissipation in the plastic dual in-line (DIP16) package.See also
Section 14.2 on
page 16.
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
= 9 V, R
L
= 16
Ω
and P
o
= 1 W at THD = 1% (see
Figure 6a),
the
Average Listening Level (ALL) – music power – without any distortion yields:
P
o(ALL)
= 1 W/15.85 = 63 mW.
The power dissipation can be derived from
Figure 11 on page 11
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
= 1 W
P
o(ALL)
= 63 mW
Power dissipation (P)
2.35 W
1.15 W
Headroom
For the average listening level a power dissipation of 1.15 W can be used for
calculation of the maximum ambient temperature T
amb(max)
(see
Section 14.2).
8.3 Mode selection
The TDA8942P 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
TDA8942P will be reduced to <0.18 mW.
9397 750 06862
© Philips Electronics N.V. 2000. All rights reserved.
Product specification
Rev. 02 — 14 March 2000
5 of 23
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