MC13110A/B MC13111A/B
52
MOTOROLA ANALOG IC DEVICE DATA
Gain Control Register
The gain control register contains bits which control the Tx
Voltage Gain, Rx Voltage Gain, and Carrier Detect threshold.
Operation of these latch bits are explained in Figures 124,
125 and 126.
Tx and Rx Gain Programming
The Tx and Rx audio signal paths each have a
programmable gain block. If a Tx or Rx voltage gain, other
than the nominal power–up default, is desired, it can be
programmed through the MPU interface. Alternately, these
programmable gain blocks can be used during final test of the
telephone to electronically adjust for gain tolerances in the
telephone system (see Figure 125). In this case, the Tx and
Rx gain register values should be stored in ROM during final
test so that they can be reloaded each time the IC is powered
up.
Figure 124. Gain Control Latch Bits
5–b Tx Gain Control
5–b Rx Gain Control
5–b CD Threshold Control
0
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áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
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áááááááááááááááááááááááááááá
Bit #2
Bit #1
á
á
Bit #4
–
0
0
1
0
á
á
Bit #3
–
1
1
1
0
–
1
1
0
ááááááááááááááááááá
ááááááááááááááááááá
1
–
0
1
0
1
Bit #0
<6
6
7
12
18
–9 dB
–9 dB
–8 dB
–3 dB
8
19
Amount
áááááááááááááááááááááááááááá
áááá
áááá
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
–
áááá
1
áááá
0
ááá
0
ááá
0
0
1
0
0
9
–7 dB
3 dB
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
áááááááááááááááááááááááááááá
0
1
0
0
1
ááááá
ááááá
ááááá
ááááá
ááááá
ááááá
4 dB
0
–6 dB
0
0
0
1
0
1
0
10
–5 dB
0
1
0
1
1
11
–4 dB
0
1
1
0
1
13
–2 dB
0
0
1
1
1
0
14
–1 dB
0
1
1
1
1
15
0 dB
1
0
0
0
0
16
1 dB
1
0
0
0
1
17
2 dB
1
1
1
0
1
0
0
20
5 dB
1
0
1
0
1
21
6 dB
1
0
1
1
0
22
7 dB
1
0
1
1
1
23
8 dB
1
1
0
0
0
24
9 dB
1
1
0
0
1
25
10 dB
–
–
–
–
–
>25
10 dB