Philips (Now NXP) TDA8920BJ, TDA8920BTH Schematic [ru]

TDA8920B

2 × 100 W class-D power ampliﬁer

Rev. 01 — 1 October 2004 Preliminary data sheet

1. General description

The TDA8920B is a high efﬁciency class-D audio power ampliﬁer with very low dissipation. The typical output power is 2 × 100 W.

The device is available in the HSOP24 power package and in the DBS23P through-hole power package. The ampliﬁer operates over a wide supply voltage range from ±12.5 V to ±30 V and consumes a very low quiescent current.

2. Features

■ Zero dead time switching

■ Advanced current protection: output current limiting

■ Smooth start-up: no pop-noise due to DC offset

■ High efﬁciency

■ Operating supply voltage from ±12.5 V to ±30 V

■ Low quiescent current

■ Usable as a stereo Single-Ended (SE) ampliﬁer or as a mono ampliﬁer in Bridge-Tied

Load (BTL)

■ Fixed gain of 30 dB in Single-Ended (SE) and 36 dB in Bridge-Tied Load (BTL)

■ High output power

■ High supply voltage ripple rejection

■ Internal switching frequency can be overruled by an external clock

■ Full short-circuit proof across load and to supply lines

■ Thermally protected.

3. Applications

■ Television sets

■ Home-sound sets

■ Multimedia systems

■ All mains fed audio systems

■ Car audio (boosters).

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4. Quick reference data

Table 1: Quick reference data

Symbol Parameter Conditions Min Typ Max Unit

General; V

q(tot)

Stereo single-ended conﬁguration

Mono bridge-tied load conﬁguration

= ±27 V

supply voltage ±12.5 ±27 ±30 V total quiescent

supply current

output power RL=3Ω; THD = 10 %; VP= ±27 V - 110 - W

output power RL=6Ω; THD = 10 %; VP= ±27 V - 210 - W

5. Ordering information

TDA8920B

2 × 100 W class-D power ampliﬁer

no load; no ﬁlter; no RC-snubber network connected

=4Ω; THD = 10 %; VP= ±27 V - 86 - W

-5065mA

Table 2: Ordering information

Type number Package

Name Description Version

TDA8920BTH HSOP24 plastic, heatsink small outline package; 24 leads; low

stand-off height

TDA8920BJ DBS23P plastic DIL-bent-SIL power package; 23 leads (straight

lead length 3.2 mm)

SOT566-3

SOT411-1

Preliminary data sheet Rev. 01 — 1 October 2004 2 of 34

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6. Block diagram

TDA8920B

2 × 100 W class-D power ampliﬁer

DDA2

3 (20)

9 (3)

IN1M

IN1P

SGND1

OSC

MODE

SGND2

IN2P

IN2M

8 (2)

11 (5)

7 (1)

6 (23)

2 (19)

5 (22)

4 (21)

SSA2

INPUT

STAGE

mute

MODE

mute

INPUT

STAGE

1 (18)

Pin numbers in parenthesis refer to the TDA8920BJ.

Fig 1. Block diagram.

DDA1

10 (4)

OSCILLATOR

12 (6)

SSA1

PWM

MODULATOR

STABI

MANAGER

PWM

MODULATOR

PROTSTABI

RELEASE1

SWITCH1 ENABLE1

TEMPERATURE SENSOR

CURRENT PROTECTION VOLTAGE PROTECTION

ENABLE2

SWITCH2

RELEASE2

19 (-)24 (17)

SSD

n.c.

CONTROL

AND

HANDSHAKE

CONTROL

AND

HANDSHAKE

DDP2

23 (16)13 (7)18 (12) 14 (8)

DRIVER

HIGH

DRIVER

LOW

TDA8920BTH (TDA8920BJ)

DRIVER

HIGH

DRIVER

LOW

17 (11)

SSP1

DDP1

SSP1

DDP2

SSP2

15 (9)

16 (10)

22 (15)

21 (14)

20 (13)

BOOT1

OUT1

BOOT2

OUT2

coa023

Preliminary data sheet Rev. 01 — 1 October 2004 3 of 34

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7. Pinning information

7.1 Pinning

SSD

DDP2

BOOT2 V

OUT2 IN2M

SSP2

n.c. MODE

STABI OSC

SSP1

OUT1 IN1M

BOOT1 V

DDP1

PROT V

TDA8920BTH

001aab217

1 2 3 4 5 6 7 8

9 10 11 12

SSA2

SGND2

DDA2

IN2P

IN1P

DDA1

SGND1

SSA1

OSC

IN1P

IN1M

DDA1

SGND1

SSA1

PROT

DDP1

BOOT1

OUT1

SSP1

STABI V

SSP2

OUT2

BOOT2

DDP2

SSD

SSA2

SGND2

DDA2

IN2M

IN2P

MODE

TDA8920B

2 × 100 W class-D power ampliﬁer

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

TDA8920BJ

001aab218

Fig 2. Pin conﬁguration TDA8920BTH. Fig 3. Pin conﬁguration TDA8920BJ.

7.2 Pin description

Table 3: Pin description

Symbol Pin Description

TDA8920BTH TDA8920BJ

SSA2

SGND2 2 19 signal ground for channel 2 V

DDA2

IN2M 4 21 negative audio input for channel 2 IN2P 5 22 positive audio input for channel 2 MODE 6 23 mode selection input: Standby, Mute or Operating mode OSC 7 1 oscillator frequency adjustment or tracking input IN1P 8 2 positive audio input for channel 1 IN1M 9 3 negative audio input for channel 1 V

DDA1

Preliminary data sheet Rev. 01 — 1 October 2004 4 of 34

1 18 negative analog supply voltage for channel 2

3 20 positive analog supply voltage for channel 2

10 4 positive analog supply voltage for channel 1

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TDA8920B

2 × 100 W class-D power ampliﬁer

Table 3: Pin description

Symbol Pin Description

TDA8920BTH TDA8920BJ

SGND1 11 5 signal ground for channel 1 V

SSA1

PROT 13 7 decoupling capacitor for protection (OCP) V

DDP1

BOOT1 15 9 bootstrap capacitor for channel 1 OUT1 16 10 PWM output from channel 1 V

SSP1

STABI 18 12 decoupling of internal stabilizer for logic supply n.c. 19 - not connected V

SSP2

OUT2 21 14 PWM output from channel 2 BOOT2 22 15 bootstrap capacitor for channel 2 V

DDP2

SSD

12 6 negative analog supply voltage for channel 1

14 8 positive power supply voltage for channel1

17 11 negative power supply voltage for channel 1

20 13 negative power supply voltage for channel 2

23 16 positive power supply voltage for channel 2 24 17 negative digital supply voltage

8. Functional description

…continued

8.1 General

The TDA8920B is a two channel audio power ampliﬁer using class-D technology. The audio input signal is converted into a digital Pulse Width Modulated (PWM) signal via

an analog input stage and PWM modulator. To enable the output power transistors to be driven, this digital PWM signal is applied to a control and handshake block and driver circuits for both the high side and low side. In this way a level shift is performed from the low power digital PWM signal (at logic levels) to a high power PWM signal which switches between the main supply lines.

A 2nd-order low-pass ﬁlter converts the PWM signal to an analog audio signal across the loudspeakers.

The TDA8920B one-chip class-D ampliﬁer contains high power D-MOS switches, drivers, timing and handshaking between the power switches and some control logic. For protection a temperature sensor and a maximum current detector are built-in.

The two audio channels of the TDA8920B contain two PWMs, two analog feedback loops and two differential input stages. It also contains circuits common to both channels such as the oscillator, all reference sources, the mode functionality and a digital timing manager.

The TDA8920B contains two independent ampliﬁer channels with high output power,high efﬁciency, low distortion and a low quiescent current. The ampliﬁer channels can be connected in the following conﬁgurations:

• Mono Bridge-Tied Load (BTL) ampliﬁer

• Stereo Single-Ended (SE) ampliﬁers.

Preliminary data sheet Rev. 01 — 1 October 2004 5 of 34

Philips Semiconductors

The ampliﬁer system can be switched in three operating modes with pin MODE:

• Standby mode; with a very low supply current

• Mute mode; the ampliﬁers are operational; but the audio signal at the output is

suppressed by disabling the VI-converter input stages

• Operating mode; the ampliﬁers are fully operational with output signal.

To ensure pop-noise free start-up the DC output offset voltage is applied gradually to the output between Mute mode and Operating mode. The bias current setting of the VI converters is related to the voltage on the MODE pin; in Mute mode the bias current setting of the VI converters is zero (VI converters disabled) and in Operating mode the bias current is at maximum. The time constant required to apply the DC output offset voltage gradually between mute and operating can be generated via an RC-network on the MODE pin. An example of a switching circuit for driving pin MODE is illustrated in

Figure 4. If the capacitor C is left out of the application the voltage on the MODE pin will

be applied with a much smaller time-constant, which might result in audible pop-noises during start-up (depending on DC output offset voltage and used loudspeaker).

In order to fully charge the coupling capacitors at the inputs, the ampliﬁer will remain automatically in the Mute mode before switching to the Operating mode. A complete overview of the start-up timing is given in Figure 5.

TDA8920B

2 × 100 W class-D power ampliﬁer

5 V

standby/

mute

mute/on

Fig 4. Example of mode selection circuit.

MODE pin

SGND

001aab172

Preliminary data sheet Rev. 01 — 1 October 2004 6 of 34

Philips Semiconductors

mode

TDA8920B

2 × 100 W class-D power ampliﬁer

audio output

modulated PWM

50 %

duty cycle

2.2 V < V

> 4.2 V

< 3 V

mode

0 V (SGND)

mode

> 4.2 V

< 3 V

mode

standby

mute

100 ms

50 %

duty cycle

mute

50 ms

operating

> 350 ms

audio output

modulated PWM

operating

time

0 V (SGND)

standby

100 ms

50 ms

> 350 ms

time

coa024

When switching from standby to mute, there is a delay of 100 ms before the output starts switching. The audio signal is available after V

has been set to operating, but not earlier

mode

than 150 ms after switching to mute. For pop-noise free start-up it is recommended that the time constant applied to the MODE pin is at least 350 ms for the transition between mute and operating.

When switching directly from standby to operating, there is a ﬁrst delay of 100 ms before the outputs starts switching. The audio signal is available after a second delay of 50 ms. For pop-noise freestart-up it is recommended that the time constant applied to the MODE pin is at least 500 ms for the transition between standby and operating.

Fig 5. Timing on mode selection input.

Preliminary data sheet Rev. 01 — 1 October 2004 7 of 34

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8.2 Pulse width modulation frequency

The output signal of the ampliﬁer is a PWM signal with a carrier frequency of approximately317 kHz. Using a 2nd-order LC demodulation ﬁlter in theapplication results in an analog audio signal across the loudspeaker. This switching frequency is ﬁxed by an external resistor R carrier frequency is between 300 kHz and 350 kHz.

Using an external resistor of 30 kΩ on the OSC pin, the carrier frequency is set to 317 kHz.

If two or more class-D ampliﬁers are used in the same audio application, it is advisable to have all devices operating at the same switching frequency by using an external clock circuit.

8.3 Protections

The following protections are included in TDA8920B:

• OverTemperature Protection (OTP)

• OverCurrent Protection (OCP)

• Window Protection (WP)

• Supply voltage protections:

– UnderVoltage Protection (UVP) – OverVoltage Protection (OVP) – UnBalance Protection (UBP).

connected between pin OSC and V

OSC

TDA8920B

2 × 100 W class-D power ampliﬁer

. An optimal setting for the

SSA

The reaction of the device on the different fault conditions differs per protection:

8.3.1 OverTemperature Protection (OTP)

If the junction temperature Tj> 150 °C, then the power stage will shut-down immediately. The power stage will start switching again if the temperature drops to approximately 130 °C, thus there is a hysteresis of approximately 20 °C.

8.3.2 OverCurrent Protection (OCP)

When the loudspeaker terminals are short-circuited or if one of the demodulated outputs of the ampliﬁer is short-circuited to one of the supply lines, this will be detected by the OverCurrent Protection (OCP). If the output current exceeds the maximum output current of 8 A, this current will be limited by the ampliﬁer to 8 A while the ampliﬁer outputs remain switching (the ampliﬁer is NOT shut-down completely).

The ampliﬁer can distinguish between an impedance drop of the loudspeaker and low-ohmic short across the load. In the TDA8920B this impedance threshold (Zth) depends on the supply voltage used.

When a short is made across the load causing the impedance to drop below the threshold level (< Zth) then the ampliﬁer is switched off completely and after a time of 100 ms it will try to restart again. If the short circuit condition is still present after this time this cycle will be repeated. The average dissipation will be low because of this low duty cycle.

Preliminary data sheet Rev. 01 — 1 October 2004 8 of 34

Philips Semiconductors

In case of an impedance drop (e.g. due to dynamic behavior of the loudspeaker) the same protection will be activated; the maximum output current is again limited to 8 A, but the ampliﬁer will NOT switch-off completely (thus preventing audio holes from occurring). Result will be a clipping output signal without any artefacts.

See also Section 13.6 for more information on this maximum output current limiting feature.

TDA8920B

2 × 100 W class-D power ampliﬁer

Preliminary data sheet Rev. 01 — 1 October 2004 9 of 34

Philips Semiconductors

8.3.3 Window Protection (WP)

During the start-up sequence, when pin MODE is switched from standby to mute, the conditions at the output terminals of the power stage are checked. In the event of a short-circuit at one of the output terminals to VDD or VSS the start-up procedure is interrupted and the system waits for open-circuit outputs. Because the test is done before enabling the power stages, no large currents will ﬂow in the event of a short-circuit. This system is called Window Protection (WP) and protects for short-circuits at both sides of the output ﬁlter to both supply lines. When there is a short-circuit from the power PWM output of the power stage to one of the supply lines (before the demodulation ﬁlter) it will also be detected by the start-up safety test. Practical use of this test feature can be found in detection of short-circuits on the printed-circuit board.

Remark: This test is operational during (every) start-up sequence at a transition between Standby and Mute mode. However when the ampliﬁer is completely shut-down due to activation of the OverCurrent Protection (OCP) because a short to one of the supply lines is made, then during restart (after 100 ms) the window protection will be activated. As a result the ampliﬁer will not start-up until the short to the supply lines is removed.

8.3.4 Supply voltage protections

TDA8920B

2 × 100 W class-D power ampliﬁer

If the supply voltage drops below ±12.5 V, the UnderVoltage Protection (UVP) circuit is activated and the system will shut-down correctly. If the internal clock is used, this switch-off will be silent and without pop noise. When the supply voltage rises above the threshold level, the system is restarted again after 100 ms. If the supply voltage exceeds ±33 V the OverVoltage Protection (OVP) circuit is activated and the power stages will shut-down. It is re-enabled as soon as the supply voltage drops below the threshold level. So in this case no timer of 100 ms is started.

An additional UnBalance Protection (UBP) circuit compares the positive analog (V and the negative analog (V

) supply voltages and is triggered if the voltage difference

SSA

DDA

)

between them exceeds a certain level. This level depends on the sum of both supply voltages. An expression for the unbalanced threshold level is as follows: V

th(ub)

≈ 0.15 × (V

DDA+VSSA

When the supply voltage difference drops below the threshold level, the system is restarted again after 100 ms.

Example: With a symmetrical supply of ±30 V, the protection circuit will be triggered if the unbalance exceeds approximately 9 V; see also Section 13.7.

In Table 4 an overview is given of all protections and the effect on the output signal.

Table 4: Overview protections TDA8920B

Protection name Complete shut-down Restart directly Restart every 100 ms

OTP Y Y OCP N WP Y UVP Y N Y OVPYYN UBP Y N Y

[2] [3]

[1] [2]

Y YN

[1]

[2]

[1] Hysteresis of 20 degrees will inﬂuence restart timing depending on heatsink size.

Preliminary data sheet Rev. 01 — 1 October 2004 10 of 34

Philips Semiconductors

[2] Only complete shut-down of ampliﬁer if short-circuit impedance is below threshold of 1 Ω. In all other cases

current limiting: resulting in clipping output signal.

[3] Fault condition detected during (every) transition between standby-to-mute and during restart after

activation of OCP (short to one of the supply lines).

8.4 Differential audio inputs

Fora high common mode rejection ratio and a maximum of ﬂexibility in the application, the audio inputs are fully differential. By connecting the inputs anti-parallel the phase of one of the channels can be inverted, so that a load can be connected between the two output ﬁlters. In this case the system operates as a mono BTL ampliﬁer and with the same loudspeaker impedance an approximately four times higher output power can be obtained.

The input conﬁguration for a mono BTL application is illustrated in Figure 6. In the stereo single-ended conﬁguration it is also recommended to connect the two

differential inputs in anti-phase. This has advantages for the current handling of the power supply at low signal frequencies.

TDA8920B

2 × 100 W class-D power ampliﬁer

Fig 6. Input conﬁguration for mono BTL application.

9. Limiting values

Table 5: Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol Parameter Conditions Min Max Unit

ORM

stg

amb

[1] Current limiting concept. See also Section 13.6.

IN1P

IN1M

IN2P

IN2M

power stage

OUT1

SGND

OUT2

mbl466

supply voltage - ±30 V repetitive peak current in

output pin

maximum output current limiting

[1]

8- A

storage temperature −55 +150 °C ambient temperature −40 +85 °C junction temperature - 150 °C

Preliminary data sheet Rev. 01 — 1 October 2004 11 of 34

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