U4089B-P_05 Datasheet, PDF (3/26 Pages) ATMEL Corporation – Monolithic Integrated Feature Phone Circuit

2. Pin Configuration
Figure 2-1. Pinning SSO44
U4089B-P
Table 2-1. Pin Description
Pin
Symbol Function
1
DTMF Input for DTMF signals. Also used for the answering machine and hands-free input.
3
MIC 2 Non-inverting input of microphone amplifier.
4
MIC 1 Inverting input of microphone amplifier.
6
IND
The internal equivalent inductance of the circuit is proportional to the value of the capacitor at this pin.
A resistor connected to ground may be used to reduce the DC line voltage.
7
V_L
Line voltage.
8
GND
Reference point for DC and AC output signals.
A small resistor (fixed) connected from this pin to V_L sets the slope of the DC characteristic, and affects
9
SENSE the line-length equalization characteristics, and the line current at which the loudspeaker amplifier is
switched on.
10
V_B
Unregulated supply voltage for peripheral circuits (voice switch); limited to typically 7V.
11
SAO
Output of loudspeaker amplifier.
13
V_MP
Regulated supply voltage 3.3V for peripheral circuits. The maximum output current is 2 mA.
Control input for selection of line impedance
1) 600Ω
20
IMPSEL 2) 900Ω
3) Mute of second transmit stage (TXA); also used for indication of external supply (answering machine);
last chosen impedance is stored.
21
TSACL Time constant of anti-clipping of speaker amplifier.
22
GSA
Current input for setting the gain of the speaker amplifier. Adjustment characteristic is logarithmical.
For RGSA > 2 MΩ, the speaker amplifier is switched off.
23
SAI
Speaker amplifier input (for loudspeaker, tone ringer and hands-free use).
Note: Filters against electromagnetic interference (EMI) are located at pins MIC1, MIC2, RECIN and STI.
3
4518C–CORD–10/05