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MC145026

MC145027

MC145028

SC41343

SC41344

Encoder and Decoder Pairs CMOS

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

MAXIMUM RATINGS* (Voltages Referenced to V_SS)

* Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the limits in the Electrical Characteristics tables or Pin Descriptions section.

This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this high–impedance circuit. For proper operation, V_in and Vout should be constrained to the range V_SS ≤ (V_in or V_out) ≤ V_DD.

PIN ASSIGNMENTS

Figure 1. MC145026 Encoder Block Diagram

Figure 2. MC145027 Decoder Block Diagram

Figure 3. MC145028 Decoder Block Diagram