MT8889C
V
DD
MT8889C
V
DD
St/GT
ESt
R1
C1
Vc
Data Sheet
t
GTA
= (R1C1) In (V
DD
/ V
TSt
)
t
GTP
= (R1C1) In [V
DD
/ (V
DD
-V
TSt
)]
Figure 5 - Basic Steering Circuit
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):
t
REC
≥
t
DPmax
+ t
GTPmax
- t
DAmin
t
REC
≤
t
DPmin
+ t
GTPmin
- t
DAmax
t
ID
≥
t
DAmax
+ t
GTAmax
- t
DPmin
t
DO
≤
t
DAmin
+ t
GTAmin
- t
DPmax
t
GTP
= (R
P
C1) In [V
DD
/ (V
DD
-V
TSt
)]
t
GTA
= (R1C1) In (V
DD
/V
TSt
)
V
DD
C1
St/GT
R
P
= (R1R2) / (R1 + R2)
R1
ESt
R2
a) decreasing tGTP; (tGTP < tGTA)
t
GTP
= (R1C1) In [V
DD
/ (V
DD
-V
TSt
)]
V
DD
C1
St/GT
t
GTA
= (R
p
C1) In (V
DD
/V
TSt
)
R
P
= (R1R2) / (R1 + R2)
R1
ESt
R2
b) decreasing tGTA; (tGTP > tGTA)
Figure 6 - Guard Time Adjustment
6
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
