MC145026, MC145027, MC145028 Technical Data, Rev. 4

10

Freescale Semiconductor

Pin Descriptions

TE

Transmit Enable (Pin 14)

This active-low transmit enable input initiates transmission when forced low. An internal pull-up device

keeps this input normally high. The pull-up current is specified in the Electrical Characteristics table.

Data Out (Pin 15)

This is the output of the encoder that serially presents the encoded data word.

Negative Power Supply (Pin 8)

The most-negative supply potential. This pin is usually ground.

Positive Power Supply (Pin 16)

The most-positive power supply pin.

4.2

MC145027 and MC145028 Decoders

A1 - A5, A1 - A9

Address Inputs (Pins 1 - 5)-MC145027,

Address Inputs (Pins 1 - 5, 15, 14, 13, 12)-MC145028

These are the local address inputs. The states of these pins must match the appropriate encoder inputs for

the VT pin to go high. The local address may be encoded with trinary or binary data.

D6 - D9

Data Outputs (Pins 15, 14, 13, 12)-MC145027 Only

These outputs present the binary information that is on encoder inputs A6/D6 through A9/D9. Only binary

data is acknowledged; a trinary open at the MC145026 encoder is decoded as a high level (logic 1).

Data In (Pin 9)

This pin is the serial data input to the decoder. The input voltage must be at CMOS logic levels. The signal

source driving this pin must be dc coupled.