mc145028 Freescale Semiconductor, Inc, mc145028 Datasheet - Page 16

• Manufacturer Part Number: mc145028
• Description: Mc145027 Encoder And Decoder Pair
• Manufacturer: Freescale Semiconductor, Inc

MC145027 and MC145028 Timing
5
To verify the MC145027 or MC145028 timing, check the waveforms on C1 (Pin 7) and R2/C2 (Pin 10) as
compared to the incoming data waveform on D
The R-C decay seen on C1 discharges down to 1/3 V
(labelled “DOS” in
is a 1 or 0. DOS should not be too close to the D
The other timing to be checked on the MC145027 and MC145028 is on R2/C2 (see
decay is continually reset to V
end-of-transmission (EOT) does R2/C2 decay significantly from V
internal end-of-word (EOW) timing edge which is generated when R2/C2 decays to 2/3 V
EOT timing edge occurs when R2/C2 decays to 1/3 V
decay should go down between the 2/3 and 1/3 V
transmission on D
Verification of the timing described above should ensure a good match between the MC145026 transmitter
and the MC145027 and MC145028 receivers.
16
MC145027 and MC145028 Timing
in
Figure
resumes.
R2/C2
16) is the point in time where the decision is made whether the data seen on D
D
C1
MC145026, MC145027, MC145028 Technical Data, Rev. 4
in
DD
V
V
V
0 V
2/3
1/3
0 V
0 V
2/3
1/3
DD
Figure 17. R-C Decay on Pin 10 (R2/C2)
DD
DD
as data is being transmitted. Only between words and after the
Figure 16. R-C Decay on Pin 7 (C1)
DOS
in
in
DD
(Pin 9).
data edges or intermittent operation may occur.
levels, but not too close to either level before data
DD
DD
. When the waveform is being observed, the R-C
before being reset to V
DOS
EOW
DD
EOT
. R2/C2 can be used to identify the
DD
. This point of reset
Freescale Semiconductor
Figure
DD
17). The R-C
. The internal
in