mt88l89asr1 Zarlink Semiconductor, mt88l89asr1 Datasheet - Page 6

• Manufacturer Part Number: mt88l89asr1
• Description: 3 V Integrated Dtmf Transceiver With Adaptive Micro Interface
• Manufacturer: Zarlink Semiconductor

Guard Time Adjustment
The simple steering circuit shown in Figure 5 is adequate for most applications. Component values are chosen
according to the following inequalities (see Figure 7):
V
St/GT
ESt
V
St/GT
ESt
DD
DD
V
MT88L89
DD
St/GT
V
ESt
Figure 6 - Guard Time Adjustment
R1
DD
Figure 5 - Basic Steering Circuit
R1
t
t
REC
REC
t
t
DO
ID
≥ t
Zarlink Semiconductor Inc.
≥ t
≤ t
≤ t
DAmax
DPmax
DAmin
DPmin
MT88L89
t
t
GTP
GTA
t
t
R1
GTP
GTP
R2
a) decreasing
b) decreasing
R2
C1
C1
= (R1C1) In [V
+ t
= (R1C1) In (V
+ t
+ t
+ t
= (R
= (R1C1) In [V
6
GTAmax
t
t
GTAmin
GTA
GTPmin
GTA
GTPmax
P
C1) In [V
R
R
Vc
P
P
= (R1C1) In (V
= (R
C1
= (R1R2) / (R1 + R2)
= (R1R2) / (R1 + R2)
- t
- t
t
t
- t
GTP
p
GTA
- t
DD
C1) In (V
DPmin
DD
DPmax
DAmax
DD
DD
DAmin
; (
; (
/ (V
/ V
/ (V
/ (V
t
t
GTP
GTP
TSt
DD
DD
DD
DD
DD
-V
)
-V
-V
>
<
TSt
/V
/V
t
t
TSt
TSt
GTA
TSt
GTA
TSt
)]
)]
)]
)
)
)
)
Data Sheet