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ML145027EP Просмотр технического описания (PDF) - Unspecified

Номер в каталогеML145027EP ETC
Unspecified 
Компоненты ОписаниеEncoder and Decoder Pairs CMOS


ML145027EP Datasheet PDF : 19 Pages
First Prev 11 12 13 14 15 16 17 18 19
ML145026, ML145027, ML145028
LANSDALE Semiconductor, Inc.
ML145027 AND ML145028 TIMING
To verify the ML145027 or ML145028 timing, check the-
waveforms on C1 (Pin 7) and R2/C2 (Pin 10) as compared to
the incoming data waveform on Din (Pin 9).
The R–C decay seen on C1 discharges down to 1/3 VDD
before being reset to VDD. This point of reset (labelled “DOS”
in Figure 15) is the point in time where the decision is made
whether the data seen on Din is a 1 or 0. DOS should not be
too close to the Din data edges or intermittent operation may
occur.
The other timing to be checked on the ML145027 and
ML145028 is on R2/C2 (see Figure 16). The R–C decay is
continually reset to VDD as data is being transmitted. Only
between words and after the end–of–transmission (EOT) does
R2/C2 decay significantly from VDD. R2/C2 can be used to
identify the internal end–of–word (EOW) timing edge which is
generated when R2/C2 decays to 2/3 VDD. The internal EOT
timing edge occurs when R2/C2 decays to 1/3 VDD. When the
waveform is being observed, the R–C decay should go down
between the 2/3 and 1/3 VDD levels, but not too close to either
level before data transmission on Din resumes.
Verification of the timing described above should ensure a
good match between the ML145026 transmitter and the
ML145027 and ML145028 receivers.
VDD
Din
0V
VDD
C1 2/3
1/3
0V
DOS
DOS
Figure 15. R ÐC Decay on Pin 7 (C1)
VDD
2/3
R2/C2 1/3
0V
EOW
EOT
F igure 16. R ÐC Decay on P in 10 (R 2/C 2)
Page 13 of 19
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Legacy Device:Motorola/Freescale MC145026, MC145027, MC145028
These devices are designed to be used as encoder/decoder pairs in remote control applications.
The ML145026 encodes nine lines of information and serially sends this information upon receipt of a transmit enable (TE) signal. The nine lines may be encoded with trinary data (low, high, or open) or binary data (low or high). The words are transmitted twice per encoding sequence to
increase security.
The ML145027 decoder receives the serial stream and interprets five of the trinary digits as an address code. Thus, 243 addresses are possible. If binary data is used at the encoder, 32 addresses are possible. The remaining serial information is interpreted as four bits of binary data. The valid transmission (VT) output goes high on the ML145027 when two conditions are met. First, two addresses must be consecutively received (in one encoding sequence) which both match the local address. Second, the 4 bits of data must match the last valid data received. The active VT indicates that the information at the Data output pins has been updated.
The ML145028 decoder treats all nine trinary digits as an address which allows 19,683 codes. If binary data is encoded, 512 codes are possible. The VT output goes high on the ML145028 when two addresses are consecutively received (in one encoding sequence) which both match the local
address.

• Operating Temperature Range: TA= – 40 to + 85°C
• Very–Low Standby Current for the Encoder: 300 nA Maximum @ 25°C
• Interfaces with RF, Ultrasonic, or Infrared Modulators and Demodulators
• RC Oscillator, No Crystal Required
• High External Component Tolerance; Can Use ± 5% Components
• Internal Power–On Reset Forces All Decoder Outputs Low
• Operating Voltage Range: ML145026 = 2.5 to 18 V*
                                     ML145027, ML145028 = 4.5 to 18 V
• For Infrared Applications, See Application Note AN1016/D

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