UBA1707 NXP Semiconductors, UBA1707 Datasheet - Page 14

• Manufacturer Part Number: UBA1707
• Description: Cordless Telephone, Answering Machine Line Interface
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Auxiliary amplifier (pins AXI and AXO; bit AXM)
The auxiliary amplifier (see Fig.12) has one input (AXI) and one output (AXO). The input impedance between pins AXI
and GND is 3.8 k . The rail-to-rail output stage is designed to drive a 500 A peak current. The output impedance at pin
AXO is approximately 100 .
The output as well as the input are biased at 2
at 31.8 dB.The amplifier can be muted by setting bit AXM at logic 1 via the serial interface. In this case, the input
impedance between pins AXI and GND is infinite.
Loudspeaker channel (see Fig.13)
L
LSPGND;
The loudspeaker amplifier has two symmetrical inputs
LSAI1 and LSAI2 selectable independently by the bits
LSA1 and LSA2 respectively. The input impedance
between pins LSAI1or LSAI2 and GND is typically 21 k .
Each of these two inputs stages can accommodate signals
up to 500 mV (RMS) at room temperature for less than 2%
of Total Harmonic Distortion (THD) at minimum voltage
gain.
The inputs are biased at 2
(whatever the state of bits LSA1 and LSA2).
The rail-to-rail output stage is designed to power a
loudspeaker connected as a single-ended load (between
pins LSAO and LSPGND). The output LSAO is able to
drive at least a 150 mA peak current.
1999 Feb 17
handbook, full pagewidth
OUDSPEAKER AMPLIFIER
Cordless telephone, answering machine
line interface
Bit names are given in italics.
BITS
LSPD, LSA1
(
PINS
AND
V
LSAI1, LSAI2, LSAO
d
AXI
LSA2)
1.4 V DC voltage
UBA1707
Fig.12 Auxiliary amplifier.
V
d
AND
1.4 V DC voltage. The voltage gain from pin AXI to pin AXO is set
AXM
14
2V d
As a result, it can drive loudspeaker loads down to 8
V
at
continuous wave drive and depends on the value of V
In order to avoid crosstalk from the loudspeaker to other
amplifiers, the loudspeaker current flows via pin LSPGND.
This pin must be externally connected to pin GND.
The nominal value of the voltage gain for maximum
volume from pins LSAI1 or LSAI2 to pin LSAO is set at
28 dB.
This amplifier is no longer supplied by setting the LSPD bit
at logic 1 via the serial interface.
CC
1
2
= 4.0 V and 16
V
CC
. Its output voltage capability is specified for
MGK712
AXO
at V
CC
= 5.5 V. The output is biased
Product specification
UBA1707
CC
at
.