tea1097h NXP Semiconductors, tea1097h Datasheet - Page 14

• Manufacturer Part Number: tea1097h
• Description: Speech And Loudspeaker Amplifier Ic With Auxiliary Inputs/outputs And Analog Multiplexer
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Loudspeaker channel
L
The TEA1097 has an asymmetrical input for the
loudspeaker amplifier with an input resistance of 20 k
between pins HFRX and GND. It is biased at two diodes
voltage. The input stage can accommodate signals up to
580 mV (RMS) at room temperature for 2% of THD.
The rail-to-rail output stage is designed to power a
loudspeaker down to 8
load (between pins LSAO and GND). When the circuit is
externally supplied, the maximum output power is equal to
280 mW (typ.) for 6 V applied to pin ESI.
The gain of the loudspeaker amplifier can be adjusted from
0 to 35 dB to suit specific application requirements.
The gain from HFRX to LSAO is proportional to the value
of R
A capacitor connected in parallel with R
recommended and provides a first-order low-pass filter.
V
The loudspeaker amplifier gain can be adjusted with the
potentiometer R
obtain logarithmic control of the gain at the loudspeaker
amplifier. Each 1.9 k increase of R
loss of 3 dB.
1999 Apr 08
handbook, full pagewidth
OUDSPEAKER AMPLIFIER
OLUME CONTROL
Speech and loudspeaker amplifier IC with
auxiliary inputs/outputs and analog multiplexer
The pin numbers given in parenthesis refer to the TEA1097H.
GALS
and equals 28 dB with R
VOL
(
C LSAO
R GALS
C GALS
PIN
. A linear potentiometer can be used to
C DLC
VOL)
:
PINS
connected as a single-ended
(11)
(12)
14
16
(8)
11
HFRX, GALS
LSAO
DLC
GALS
GALS
VOL
DYNAMIC
LIMITER
= 255 k .
GALS
results in a gain
V BB
AND
is
Fig.8 Loudspeaker channel.
LSAO
V
I
14
logic
to
D
The dynamic limiter of the TEA1097 prevents clipping of
the loudspeaker output stage and protects the operation of
the circuit when the supply voltage at V
Hard clipping of the loudspeaker output stage is prevented
by rapidly reducing the gain when the output stage starts
to saturate. The time in which gain reduction is effected
(clipping attack time) is approximately a few milliseconds.
The circuit stays in the reduced gain mode until the peaks
of the loudspeaker signals no longer cause saturation.
The gain of the loudspeaker amplifier then returns to its
normal value within the clipping release time (typically
100 ms). Both attack and release times are proportional to
the value of the capacitor C
distortion of the loudspeaker output stage, in reduced gain
mode, stays below 1% up to 10 dB (min.) of input voltage
overdrive [providing V
When the supply voltage drops below an internal threshold
voltage of 2.7 V, the gain of the loudspeaker amplifier is
rapidly reduced (approximately 1 ms). When the supply
voltage exceeds 2.7 V, the gain of the loudspeaker
amplifier is increased again. By forcing a level lower than
0.2 V on pin DLC, the loudspeaker amplifier is muted.
YNAMIC LIMITER
I
V
CONTROL
VOLUME
(
PIN
HFRX
MGL394
DLC)
HFRX
VOL
(1)
(23)
is below 580 mV (RMS)].
27
7
DLC
R VOL
. The total harmonic
Product specification
BB
falls below 2.7 V.
TEA1097