Data Sheet
Pin Description
Pin #
23
24
3
Symbol
M1
M2
RO
Function
Microphone Inputs
Differential inputs for the microphone (electret).
AS2533...6
Receive Output
This is the output for driving a dynamic earpiece with an impedance of 140 to 300
Ω.
Analogue Ground
This is the analogue ground for the amplifiers.
Receive Input
This is the input for the receive signal.
Side Tone Balance Input
This is the input for side tone cancellation.
Line Current Sense Input
This is the input for sensing the line current.
Line Input
This input is used for power extraction and line current sensing.
Current Shunt Control Output
This N-channel open drain output controls the external high power shunt transistor for the
modulation of the line voltage and for shorting the line during make period of pulse dialling.
Positive Voltage Supply
This is the supply pin for the circuit.
Negative Power Supply
Melody Output
PDM output of the melody generator for tone ringing. Hi-Z when not active.
Frequency Comparator Input
This is a Schmitt trigger input for ring frequency discrimination. Disabled during off-hook.
Hook Switch Input and Dial Pulse Output
This is an I/O that is pulled high by the hook switch when off-hook and an open drain pulls
it low during break periods of pulse dialling and flash.
Oscillator Input
Pin for ceramic resonator (3.58 MHz). Recommended: Murata CSA 3.58MG312AM.
Line Loss Compensation
Select pin for line loss compensation (see also figure 4 to 7).
LLC = A
GND
: 20 - 50 mA
LLC = V
DD
: 45 - 75 mA
LLC = V
SS
: none.
LED Output Driver
Output for driving an LED that will be flashing when in Programme/Mute state.
5
A
GND
RI
28
6
STB
1
LS
27
LI
25
CS
4
V
DD
V
SS
MO
26
8
21
FCI
10
HS/DP
11
OSC
9
LLC
22
LED
Continues…
Rev. 7
2
July 1998
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
