Vitek VT-3485new DATASHEET

TFA9842J

2-channel audio ampliﬁer; SE: 1 W to 7.5 W; BTL: 2 W to 15 W

Rev. 01 — 26 April 2004 Preliminary data

1. General description

The TFA9842J contains two identical audio power ampliﬁers. The TFA9842J can be used as two Single-Ended (SE) channels with a ﬁxed gain of 26 dB or one Bridge-Tied Load (BTL) channel with a ﬁxed gain of 32 dB.

The TFA9842J comes in a 9-pin DIL-bent-SIL (DBS9P) power package. The TFA9842J is pin compatible with the TFA9841J and TFA9843J.

The TFA9842J contains a unique protection circuit that is solely based on multiple temperature measurements inside the chip. This gives maximum output power for all supply voltages and load conditions with no unnecessary audio holes. Almost any supply voltage and load impedance combination can be made as long as thermal boundary conditions (number of channels used, external heatsink and ambient temperature) allow it.

2. Features

3. Applications

■ SE: 1 W to 7.5 W; BTL: 2 W to 15 W operation possibility

■ Soft clipping

■ 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

■ Pin compatible with the TFA9841J and TFA9843J.

■ Television

■ PC speakers

■ Boom box

■ Mini and micro audio receivers.

Philips Semiconductors

4. Quick reference data

Table 1: Quick reference data

Symbol Parameter Conditions Min Typ Max Unit

stb

THD total harmonic

SVRR supply voltage ripple

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

supply voltage operating 9 17 26 V

no signal - - 28 V

quiescent supply current

standby supply current - - 10 µA output power VCC=17V; THD=10%

distortion voltage gain SE 25 26 27 dB

rejection

VCC=18V; RL= ∞ - 60 100 mA

=4Ω 7 7.5 - W

SE; R

BTL; R SE; P BTL; P

=8Ω 14 15 - W

= 1 W - 0.1 0.5 %

= 1 W - 0.05 0.5 %

BTL 31 32 33 dB f=1kHz

SE - 60 - dB

BTL - 65 - dB

5. Ordering information

Table 2: Ordering information

Type number

TFA9842J DBS9P plastic DIL-bent-SIL power package; 9 leads

Package Name Description Version

SOT523 -1

(lead length 12/11 mm); exposed die pad

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Preliminary data Rev. 01 — 26 April 2004 2 of 21

Philips Semiconductors

6. Block diagram

IN1+

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

60 kΩ

OUT1+

Fig 1. Block diagram.

7. Pinning information

7.1 Pinning

IN2+

CIV

MODE

60 kΩ

REF

STANDBY

MUTE

TFA9842J

GND

SHORT-CIRCUIT

AND

TEMPERATURE

PROTECTION

0.5V

MDB801

OUT2−

SVR

IN2

OUT2−

CIV

IN1+

GND

TFA9842J

SVR

MODE

OUT1+

MDB802

Fig 2. Pin conﬁguration.

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Preliminary data Rev. 01 — 26 April 2004 3 of 21

Philips Semiconductors

7.2 Pin description

Table 3: Pin description

Symbol Pin Description

IN2+ 1 input 2 OUT2− 2 inverted loudspeaker terminal 2 CIV 3 common input voltage decoupling IN1+ 4 input 1 GND 5 ground SVR 6 half supply voltage decoupling (ripple rejection) MODE 7 mode selection input (standby, mute and operating) OUT1+ 8 non inverted loudspeaker terminal 1 V

TAB - back side tab or heats spreader has to be connected to ground

8. Functional description

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

9 supply voltage

8.1 Input conﬁguration

The input cut-off frequency is:

i cut off–()

SE application: Ri=60kΩ and Ci= 220 nF:

i cut off–()

BTL application: Ri=30kΩ and Ci= 470 nF:

i cut off–()

As shown in Equation 2 and Equation 3, 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 behavior.

---------------------------- -

2π RiCi×()

---------------------------------------------------------------- -

12 Hz==

2π 60 103× 220× 109–×()

---------------------------------------------------------------- -

11 Hz==

2π 30 103× 470× 109–×()

(1)

(2)

(3)

8.2 Power ampliﬁer

The power ampliﬁer is a Single-Ended (SE) and/or Bridge-Tied Load (BTL) ampliﬁer with an all-NPN output stage, capable of delivering a peak output current of 3 A.

Using the TFA9842J as a BTL ampliﬁer offers the following advantages:

• Lower peak value of the supply current

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Preliminary data Rev. 01 — 26 April 2004 4 of 21

Philips Semiconductors

• 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 6.

The maximum output powerislimitedbythesupplyvoltage of 26 Vandthemaximum availableoutputcurrentis 3 A (repetitive peak current). A minimum load for SE of 4 Ω and for BTL of 16 Ω is required for VCC> 22 V; see Figure 5.

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 VCC= 18 V and Po= 5 W (SE with RL=4Ω) or Po= 10 W (BTL with RL=8Ω) at THD = 0.2 % (see Figure 7), the Average Listening Level (ALL) music power without any distortion yields:

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

510

oALLSE,()

o ALL BTL,()

⋅

---------------

15.85

10 103⋅

------------------

15.85

315 mW==

630 mW==

The power dissipation can be derived from Figure 9 (SE and BTL) for a headroom of 0 dB and 12 dB, respectively (see Table 4).

Table 4: Power rating as function of headroom

Headroom Power output Power dissipation

SE BTL

0dB P 12 dB P

=5W Po=10W PD= 8.4 W

= 315 mW P

o(ALL)

= 630 mW PD= 4.2 W

o(ALL)

(both channels driven)

For the average listening level a power dissipation of 4.2 W can be used for a heatsink calculation.

8.3 Mode selection

The TFA9842J has three functional modes, which can be selected by applying the proper DC voltage to pin MODE (see Table 5 and Figure 3).

(4)

(5)

Table 5: Mode selection

MODE

0 to 0.8 V standby

4.5 V to (V

− 2.0 V) to V

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Preliminary data Rev. 01 — 26 April 2004 5 of 21

− 3.5 V) mute

Ampliﬁers 1 and 2

Philips Semiconductors

Standby — The current consumption is very low and the outputs are ﬂoating. The

device is in standby mode when V Mute — The ampliﬁer isDC-biased but not operational (noaudio output). Thisallows

the input coupling capacitors to be charged to avoid pop-noise. The deviceis in mute mode when 4.5V<V

On — The ampliﬁer is operating normally. The operating mode is activated at V

MODE

>(VCC− 2.0 V).

standby all mute 1/2 on

<(VCC− 3.5 V).

MODE

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

< 0.8 V, or when pin MODE is grounded.

MODE

0.8 4.5 VCC−3.5 V

Fig 3. Mode selection.

VCC−2.0

MODE

(V)

MCE502

8.4 Supply voltage ripple rejection

The supply voltage ripple rejection (SVRR) is measured with an electrolytic capacitor of 150 µF on pin SVR using a bandwidth of 20 Hz to 22 kHz. Figure 11 illustrates the SVRR as function of the frequency. A larger capacitor valueon pin SVR improves the ripple rejection behavior at the lower frequencies.

8.5 Built-in protection circuits

The TFA9842J contains two types of temperature sensors; one measures local temperatures of the power stages and one measures the global chip temperature.At a local temperature of the power stage of approximately 185oC or a global temperature of approximately 150oC this detection circuit switches off the power stages for 2 ms. High impedance ofthe outputs is the result.After this time period the power stages switch on automatically and the detection will take place again; still a too high temperature switches off the power stages immediately. This protects the TFA9842J against shorts to ground, to the supply voltage, across the load and too high chip temperatures.

The protection will only be activated when necessary, so even during a short-circuit condition, a certain amount of (pulsed) current will still be ﬂowing through the short, just as much as the power stage can handle without exceeding the critical temperature level.

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Preliminary data Rev. 01 — 26 April 2004 6 of 21

Philips Semiconductors

TFA9842J

2-channel audio ampliﬁer (2 x SE or 1 x BTL)

9. Limiting values

Table 6: Limiting values

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

Symbol Parameter Conditions Min Max Unit

supply voltage operating −0.3 +26 V

no signal −0.3 +28 V

ORM

stg

amb

tot

CC(sc)

input voltage −0.3 VCC+ 0.3 V repetitive peak output current - 3 A storage temperature non-operating −55 +150 °C ambient temperature operating −40 +85 °C total power dissipation - 35 W supply voltage to guarantee short-circuit

-24V

protection

10. Thermal characteristics

Table 7: Thermal characteristics

Symbol Parameter Conditions Value Unit

R R

th(j-a) th(j-c)

thermal resistance from junction to ambient in free air 40 K/W thermal resistance from junction to case both channels driven 2.0 K/W

11. Static characteristics

Table 8: Static characteristics

VCC=17V; T

Symbol Parameter Conditions Min Typ Max Unit

stb

∆V

OUT

MODE

[1] A minimum load for BTL of 16 Ω is required at VCC>22V. [2] With a load connected at the outputs the quiescent supply current will increase. [3] The DC output voltage with respect to ground is approximately 0.5VCC. [4] ∆V

OUT

=25°C; RL=8Ω; V

amb

MODE=VCC

supply voltage operating quiescent supply current RL= ∞ standby supply current V DC output voltage differential output voltage offset BTL mode

; Vi= 0 V; measured in test circuit Figure 13; unless otherwise speciﬁed.

[1]

9 1726V

[2]

- 60 100 mA

=0 --10µA

MODE

[3]

-9-V

[4]

- - 200 mV

mode selection input voltage on mode VCC− 2.0 - V

mute mode 4.5 - V standby mode 0 - 0.8 V

input current on pin MODE 0 < V

= V

OUT1+

− V

OUT2−



MODE<VCC

− 3.5 - - 20 µA

− 3.5 V

9397 750 12013

Preliminary data Rev. 01 — 26 April 2004 7 of 21

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Vitek VT-3485new DATASHEET

Specifications and Main Features

Frequently Asked Questions

User Manual

1. General description

2. Features

3. Applications

4. Quick reference data

5. Ordering information

6. Block diagram

7. Pinning information

7.1 Pinning

7.2 Pin description

8. Functional description

8.3 Mode selection

8.4 Supply voltage ripple rejection

8.5 Built-in protection circuits

9. Limiting values

10. Thermal characteristics

11. Static characteristics