U4090B-P Datasheet, PDF (5/35 Pages) ATMEL Corporation – Monolithic Integrated Feature Phone Circuit EMI Improved

U4090B-P
Table 2-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Pin Description
Symbol Function
GT
DTMF
A resistor from this pin to GND sets the amplification of the microphone and DTMF signals, the input
amplifier can be muted by applying VMP to G_T
Input for DTMF signals, also used for the answering machine and hands-free input
MICO Output of microphone preamplifier
MIC2
Non-inverting input of microphone amplifier
MIC1
Inverting input of microphone amplifier
PD
Active high input for reducing the current consumption of the circuit, simultaneously V_L is shorted by an
internal switch
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
VL
Line voltage
GND
Reference point for DC- and AC-output signals
SENSE
A small resistor (fixed) connected from this pin to V_L sets the slope of the DC characteristic and also
effects the line-length equalization characteristics and the line current at which the loudspeaker amplifier
is switched on
VB
Unregulated supply voltage for peripheral circuits (voice switch), limited to typically 7V
SAO
Output of loudspeaker amplifier
VMPS Unregulated supply voltage for micorcontroller, limited to 6.3V
VMP
Regulated supply voltage of 3.3V for peripheral circuits (especially microprocessors), minimum output
current: 2 mA (ringing) 4 mA (speech mode)
SWOUT Output for driving external switching transistor
COSC 40-kHz oscillator for ringing power converter
VRING Input for ringing signal protected by internal Zener diode
THA
Threshold adjustment for ringing frequency detector
RFDO Output of ringing frequency detector
LIDET Line detect; output is low when the line current is more than 15 mA
IMPSEL
Control input for selection of line impedance
1. 600Ω
2. 900Ω
3. Mute of second transmit stage (TXA); also used for indication of external supply (answering machine);
last chosen impedance is stored
TSACL Time constant of anti-clipping of speaker amplifier
GSA
Current input for setting the gain of the speaker amplifier, adjustment characteristic is logarithmical, or
RGSA > 2 MΩ, the speaker amplifier is switched off
SA I
Speaker amplifier input (for loudspeaker, tone ringer and hands-free use)
MUTX
Three-state input of transmit mute:
1. Speech condition; inputs MIC1/MIC2 active
2. DTMF condition; input DTMF active. A part of the input signal is passed to the receiving amplifier as a
confidence signal during dialing
3. Input DTMF used for answering machine and hands-free use; receive branch not affected
ATAFS
Attenuation of acoustical feedback suppression, maximum attenuation of AFS circuit is set by a resistor
at this pin, without the resistor, AFS is switched off
INLDT Input of transmit level detector
INLDR Input of receive level detector
TLDT Time constant of transmit level detector
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4741C–CORD–11/05