TDA8947J Datasheet, PDF (5/24 Pages) NXP Semiconductors – 4-channel audio amplifier (SE: 1 W to 25 W; BTL: 4 W to 50 W)

Philips Semiconductors
TDA8947J
4-channel audio amplifier
Table 3:
Symbol
CIV
OUT3−
GND2
V_CC2
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 R_i = 60 kΩ and C_i = 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 R_i = 30 kΩ and C_i = 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.
5 of 24