
34
Description of the Radio Interfaces
TM8000 3DK Hardware Developer’s Kit
Application Manual
September 2003
© Tait Electronics Ltd
Analogue signals (for signals not listed here refer to the Auxiliary interface specification)
DC input range:
VOL_WIP_DC
0
0
0.6
10
V
k
Ω
Voltage/resistance for min/
max volume respectively.
This line is used for control-head
detection. An open-circuit input
is considered as no head fitted.
DC bias:
SPK+/–
CH_MIC_AUD
2.9
0.5Vs
3.1
V
V
Audio PA on.
Via 2.2k
Ω
Bias for electret microphone.
Input resistance:
CH_MIC_AUD
2.1
2.2
2.3
k
Ω
Output resistance:
SPK+/–
0.5
Ω
Audio PA on.
Output load:
+3V3
+13V8
100
1
mA
A
Specification must be derated by
load amount from internal
options and auxiliary interfaces.
Safe DC input limits:
VOL_WIP_DC
RX_AUD
SPK+/–
CH_MIC_AUD
–7
–17
0
–17
+17
+7
+17
+17
V
V
V
V
Short circuit-safe.
Table 2.20
Control-head connector - DC characteristics (continued)
Parameter
Standard
Test method and
conditions
Comments
min.
typ.
max.
units
Table 2.21
Control-head connector - AC characteristics
Parameter
Standard
Test method and
conditions
Comments
min.
typ.
max.
units
RX_AUD
refer to
CH_MIC_AUD
refer to AUX_MIC_AUD in
SPK+/–
refer to
Table 2.22
Control-head connector - speaker output characteristics
Parameter
Standard
Test method and conditions
Comments
min.
typ.
max.
units
Mute ratio
70
75
dB
With respect to maximum
output power. Noise measured in
0.3-3kHz bandwidth.
Signal path muted. Audio PA
on.
Receive audio
frequency response
Refer to plot in
EIA-603B
Internal speaker output:
Load configuration
Balanced
Load
12.8
16
19.2
Ω
At 1kHz.
Maximum power
3
W
Into 16
Ω.
Rated duty cycle
100
%
At maximum power.
Concurrent speaker
output:
Rated duty cycle
33
%
1min at maximum power
2min Rx standby
The internal and external
speaker loads are connected
in parallel (not switched).