FX829 Datasheet, PDF (5/34 Pages) CML Microcircuits – Baseband Signal Processor

Baseband Signal Processor
FX829
1.3 Signal List (continued)
Package
D2/D5
Signal
Description
Pin No.
Name
Type
9
CARDCAP
O/P The carrier detect integrating capacitor.
10
V_BIAS
O/P A bias line for the internal circuitry, held at
½ V_DD. This pin must be decoupled by a
capacitor mounted close to the device pins.
11
MIC
I/P The ac coupled Tx audio input (external
amplification is required for use as a microphone
input).
12
Vss
13
DEMODIN
Power The negative supply rail (ground).
I/P The ac coupled inverting input to the Rx input
amplifier (AMP1).
14
DEMODFB
O/P The output of the Rx input amplifier (AMP1) and
the input to the audio filter/limiter section.
15
FILTER OUT
16
FFSK/DTMFOUT
17
SUM IN
O/P Output of the audio filter/limiter section. In
powersave mode this output is connected to
V_BIAS via a 500kΩ resistor.
O/P The 1200 or 2400 baud FFSK Tx output and the
DTMF encoder output. When enabled but not
transmitting FFSK or DTMF signals, or when in
powersave mode, this output is connected to
V_BIAS via a 500kΩ resistor.
On power-up, this output can be any level: a
General Reset command is required to ensure
that this output attains V_BIAS initially.
I/P Input to the audio summing amplifier (AMP2).
18
SUM OUT
O/P Output of the audio summing amplifier (AMP2).
19
MOD1 IN
I/P Input to MOD1 audio gain control.
20
VOL IN
I/P Input to the audio volume control.
21
AUDIO OUT
O/P Output of the audio volume control.
22
MOD1
O/P Output of MOD1 audio gain control.
© 1997 Consumer Microcircuits Limited
5
D/829/4