Philips TDA8943SF - Manual (Page 4)

Philips Semiconductors
TDA8943SF
7 W mono BTL audio amplifier
Preliminary specification 14 April 1999 4 of 12
9397 750 04877 © Philips Electronics N.V. 1999. All rights reserved.
7.2 Pin description
8. Functional description
The TDA8943SF is a mono BTL audio power amplifier capable of delivering 7 W
output power to an 8
Ω
load at THD = 10%, using a 12 V power supply and an
external heatsink. The voltage gain is fixed at 32 dB.
With the three-level MODE input the device can be switched from ‘standby’ to ‘mute’
and to ‘operating’ mode.
The TDA8943SF outputs are protected by an internal thermal shutdown protection
mechanism and a short-circuit protection.
8.1 Power amplifier
The power amplifier is a Bridge Tied Load (BTL) amplifier with an all-NPN output
stage, capable of delivering a peak output current of 1.5 A.
The BTL principle offers the following advantages:
• Lower peak value of the supply current
• The ripple frequency on the supply voltage is twice the signal frequency
• No expensive DC-blocking capacitor
• Good low frequency performance.
8.2 Mode selection
The TDA8943SF has three functional modes, which can be selected by applying the
proper DC voltage to pin MODE.
Standby — In this mode the current consumption is very low and the outputs are
floating. The device is in standby mode when V
MODE
> (V
CC
−
0.5 V), or when the
MODE pin is left floating.
Mute — In this mode the amplifier is DC-biased but not operational (no audio output).
This allows the input coupling capacitors to be charged to avoid pop-noise. The
device is in mute mode when 2.5 V < V
MODE
< (V
CC
−
1.5 V).
Table 4: Pin description
Symbol Pin Description
OUT
−
1 negative loudspeaker terminal
V
CC
2 supply voltage
OUT+ 3 positive loudspeaker terminal
IN+ 4 positive input
IN
−
5 negative input
SVR 6 half supply voltage decoupling (ripple rejection)
MODE 7 mode selection input (standby, mute, operating)
GND 8 ground
n.c. 9 not connected