mc145027 pdf

These devices are designed to be used as encoder/decoder pairs in remote
control applications.
The MC145026 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 MC145027 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 MC145027 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 MC145028 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 MC145028 when two addresses are consecutively
received (in one encoding sequence) which both match the local address.
• Operating Temperature Range: – 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: MC145026 = 2.5 to 18 V*
MC145027, MC145028 = 4.5 to 18 V
• Low–Voltage Versions Available:
SC41343 = 2.8 to 10 V Version of the MC145027
SC41344 = 2.8 to 10 V Version of the MC145028
• For Infrared Applications, See Application Note AN1016/D