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PDF TDA8921TH Data sheet ( Hoja de datos )
| Número de pieza | TDA8921TH | |
| Descripción | Class-D audio amplifier 2 x 50W single chip | |
| Fabricantes | Philips | |
| Logotipo |  |
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Philips Semiconductors
file: /user/nybuiten/n7260/specificatie/TDS8921N1F.fm
TDA8921TH
2 x 50 W class-D audio amplifier
mei 09, 2001
Tentative specification
TDA8921TH class-D audio amplifier 2 x 50W
single chip
1. General description
The TDA8921 is an high efficiency class-D audio power amplifier system. Typical output power is 2 x 50 W and it op-
erates with high efficiency and very low dissipation. The devices comes in a HSOP24 power package with a small
internal heatsink. No external heatsink is required, or depending on supply voltage and load a very small one. The
system operates over a wide supply voltage range from +15 up to =+30 V and consumes a very low quiescent current.
2. Features
- High efficiency (>90%)
- Operating voltage from +15 V to + 30V
- Very low quiescent current
- Low distortion
- Fixed gain of 30 dB in Single Ended and 36 dB in BTL
- High output power
- Good ripple rejection
- Internal switching frequency can be overruled by an external clock
- No switch-on or switch-off plop noise
- Short-circuit proof across the load
- Usable as a stereo Single-Ended (SE) amplifier or
as a mono amplifier in Bridge-Tied Load (BTL)
- Electrostatic discharge protection (pin to pin)
- Thermally protected
3. Applications
- Television sets
- Home-sound sets
- Multimedia systems
- All mains fed audio systems
- Car audio (boosters)
4. Quick reference data
SYMBOL
PARAMETER
General, Vp = + 25V
Vp
Iq(tot)
η
operating supply voltage
total quiescent current
efficiency
Stereo single-ended configuration
Po
Po
Gv
Zi
Vn(o)
SVRR
αcs
|Vo
output power, RLOAD = 8 ohm
output power, RLOAD = 4 ohm
closed loop voltage gain
input impedance
noise output voltage
supply voltage ripple rejection
channel separation
DC output offset voltage
CONDITIONS
MIN. TYP. MAX. UNIT
Po = 30 W
+15 +25 +30 V
- 55 75 mA
- 90 - %
THD = 10%, Vp= + 25 V 30
THD = 10%, Vp= + 21 V 40
29
45
-
40
-
37 -
W
50 -
W
30 31 dB
68 -
kΩ
200 400 µV
50 -
dB
65 -
dB
0 150 mV
Tentative specification
1
1 page  
Philips Semiconductors
TDA8921TH
2 x 50 W class-D audio amplifier
8. Functional description
The TDA8921TH is a two channel audio power amplifier system using the class-D technology. In the analog controller
part the analog audio input signal is converted into a digital PWM signal. For driving the low pass filter and the loud-
speaker load a digital power stage is used. It performs a level shift from the low power digital PWM signal at logic
levels to a high power PWM signal switching between the main supply lines. A second order low pass filter converts
the PWM signal to an analog audio signal across the loudspeaker.
Digital power stage
It contains the high power D-MOS switches, the drivers, timing and handshaking between the power switches and
some control logic. For protection a temperature sensor and a maximum current detector is on the chip.
Analog low power controller
For the two audio channels it contains two pulse width modulators (PWM), two analog feedback loops and two
differential input stages. Furthermore it contains circuits common to both channels like the oscillator, all reference
sources, the mode functionality and a digital timing manager.
Using this chip an audio system with two independent amplifier channels with high output power, high efficiency
(90%), low distortion and a low quiescent current is obtained. The amplifiers channels can be connected in the
following configurations:
- Mono bridge-tied load (BTL) amplifier
- Stereo single-ended (SE) amplifiers.
The amplifier system can be switched in three operating modes with the MODE select pin:
- Standby mode, with a very low supply current.
- Mute mode, the amplifiers are operational, but the audio signal at the output is suppressed.
- Operating mode (amplifier fully operational) with output signal.
For suppressing pop noise the amplifier will remain automatically for approx. 220ms in the mute mode before
switching to operating. In this time the coupling capacitors at the input are fully charged. See fig. 5 for an example
of a switching circuit for driving the mode pin.
Pulse Width Modulation (PWM) frequency
+5V
The output signal of the amplifier is a PWM signal with a carrier frequency of
approx. 350 kHz. Using a second order LC demodulation filter in the application
results in an analog audio signal across the loudspeaker. This switching
frequency is fixed by an external resistor ROSC connected between pin OSC
and VSS. With the resistor value given in the schematic of the reference design,
the carrier frequency is typical 350 kHz. The carrier frequency can be calculated
using:
standby/
mute
R
R
mute/on
MODE pin
SGND
fosc = 9 x 109 / Rosc [Hz]
If two or more class-D systems are used in the same audio application, it is
advised to have all devices working at the same switching frequency. This can Figure 3. Mode select circuit
be realized by connecting all OSC pins together and feed them from a external
central oscillator. Using an external oscillator it is necessary to force the OSC pin to a DC-level above SGND for
switching form internal to external oscillator. In this case the internal oscillator is disabled and the PWM will be
switching on the external frequency.The frequency range of the external oscillator must be in the range as specified
in the switching characteristics.
Application in a practical circuit:
Internal oscillator:
external oscillator:
Rosc connected from OSC pin to VSS
connect oscillator signal between OSC pin and SGND pin; delete Rosc
Tentative specification
5
5 Page 
Philips Semiconductors
TDA8921TH
2 x 50 W class-D audio amplifier
Mono BTL application
Vp = +21 V; fi = 1 kHz; Tamb = 25 °C; measured in Fig. tbf; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP. MAX. UNIT
Po
THD
Gv
SVRR
Zi
Vn(o)
Vo
CMRR
output power, RLOAD = 8 ohm
total harmonic distortion
closed loop voltage gain
supply voltage ripple rejection
input impedance
noise output voltage
output signal in mute
common mode rejection ratio
Vp = + 21V; THD = 0.5%
Vp = + 21V; THD = 10%
Po = 1 W; note 1
fi = 1 kHz
fi = 10 kHz
70
80
-
-
35
on; fi = 100 Hz; note 3 -
on; fi = 1 kHz; note 4 36
mute; fi = 100 Hz; note 3 -
standby; fi=100 Hz; note 3 -
22
on; Rs = 0 Ω; note 5
on; Rs = 10 kΩ; note 6
mute; note 7
-
-
-
note 8
-
Vi(CM)(rms) = 1 V
-
*)
*)
80 -
100 -
W
W
0.01 0.05 %
0.1 -
%
36 37 dB
49 -
dB
44 -
dB
49 -
dB
80 -
dB
34 kΩ
280 500 µV
300 -
µV
280 -
µV
- 500 µV
75 -
dB
Notes
1. Total Harmonic Distortion is measured in a bandwidth of 22 Hz to 22 kHz. When distortion is measured using a
low order lowpass filter a significant higher value will be found, due to the switching frequency outside the audio
band.
2. Output power measured across the loudspeaker load.
3. Vripple = Vripple(max) = 2 V (p-p); fi = 100 Hz; Rs = 0 Ω.
4. Vripple = Vripple(max) = 2 V (p-p); fi = 1 kHz; Rs = 0 Ω.
5. B = 22 Hz to 22 kHz; Rs = 0 Ω.
6. B = 22 Hz to 22 kHz; Rs = 10 kΩ.
7. B = 22 Hz to 22 kHz; independent of Rs.
8. Vi = Vi(max) = 1 V (RMS).
*) indirect measured, based on Rds_on measurement
Tentative specification
11
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| PDF Descargar | [ Datasheet TDA8921TH.PDF ] | |
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