mt8870dsr1-1 Zarlink Semiconductor, mt8870dsr1-1 Datasheet - Page 8

• Manufacturer Part Number: mt8870dsr1-1
• Description: Integrated Dtmf Receiver With Enhance Sensitivity
• Manufacturer: Zarlink Semiconductor

Applications
Receiver System for British Telecom Spec POR 1151
The circuit shown in Fig. 9 illustrates the use of MT8870D-1 device in a typical receiver system. BT Spec defines
the input signals less than -34 dBm as the non-operate level. This condition can be attained by choosing a suitable
values of R
gain setting pin GS of MT8870D-1. As shown in the diagram, the component values of R
time requirements when the total component tolerance is 6%. For better performance, it is recommended to use the
non-symmetric guard time circuit in Fig. 8.
1
and R
2
to provide 3 dB attenuation, such that -34 dBm input signal will correspond to -37 dBm at the
Table 2 - Recommended Resonator Specifications
Note: Qm=quality factor of RLC model, i.e., 1/2ΠƒR1C1.
Parameter
Figure 8 - Non-Symmetric Guard Time Circuit
V
St/GT
ESt
DD
Qm
R1
C1
C0
L1
∆f
MT8870D/MT8870D-1
R
1
Zarlink Semiconductor Inc.
t
Ohms
GTP
Unit
mH
pF
pF
C
%
R
8
-
=(R
1
2
t
GTA
P
C
=(R
1
)In[V
R
P
1
C
=(R
Notes:
R
R
C
DD
1
)In(V
1
2
1
1
=368 K Ω ± 1%
=2.2 M Ω ± 1%
=100 nF ± 5%
/(V
Resonator
R
2
DD
10.752
37.915
896.37
DD
)/(R
±0.2%
4.984
.432
-V
/V
1
TSt
+R
TSt
)]
)
2
)
3
and C
2
Data Sheet
are the guard