TDA8947J Просмотр технического описания (PDF) - Philips Electronics

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TDA8947J

4-channel audio amplifier (SE: 1 W to 25 W; BTL: 4 W to 50 W)

Philips Electronics 

Philips Semiconductors

TDA8947J

4-channel audio amplifier

Table 3:

Symbol

CIV

OUT3−

GND2

VCC2

OUT4+

TAB

Pin description…continued

Pin

Description

13

common input voltage decoupling

14

inverted loudspeaker output of channel 3

15

ground of channels 3 and 4

16

supply voltage channels 3 and 4

17

non inverted loudspeaker output of channel 4

-

back side tab or heats spreader has to be connected to

ground

8. Functional description

8.1 Input configuration

The input cut-off frequency is:

f i(cut – off ) = 2----π---(---R---1-i---×----C-----i-)-

(1)

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

f i(cut – off ) = -2---π---(---6---0----×-----1---0---3---1-×-----2---2---0----×-----1---0---–---9--)- = 12 Hz

(2)

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

f i(cut – off ) = -2---π---(---3---0----×-----1---0---3---1-×-----4---7---0----×-----1---0---–---9--)- = 11 Hz

(3)

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.

8.2 Power amplifier

The power amplifier is a BTL and/or SE amplifier with an all-NPN output stage,

capable of delivering a peak output current of 4 A.

Using the TDA8947J as a BTL amplifier offers the following advantages:

• Low peak value of the supply current

• Ripple frequency on the supply voltage is twice the signal frequency

• No expensive DC-blocking capacitor

• Good low frequency performance.

9397 750 10779

Preliminary data

Rev. 01 — 06 February 2004

© Koninklijke Philips Electronics N.V. 2004. All rights reserved.

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