CS212 datasheet(6/7 Pages) CHERRY

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TYPICAL WRITE WORD:

Assume CS212 #2 is to be updated so that OUT0=1 and

OUT1=0.

OUTPUTS

1. OUT0 and OUT1: Pin #'s 1, 16:

These outputs are updated according to the information

present during the write word.

2. DSR: Pin #15:

The DSR pin is a monitor of the clock signal for the on-

chip D flip flops, corresponding to OUT0 and OUT1. It

can be used to strobe data from OUT0 and OUT1 into

external circuitry connected to the CS212.

These three outputs can sink up to 1mA at 1.2V. They are

Darlington type open collector outputs.

3. Data Out: Pin #11:

The Data Out pin is used to transmit the status of IN0

and IN1 to the line. For Data=1, the line driver is off. For

Data=0, the line driver is turned on. This output is a sat-

urated switch capable of sinking 10mA DC at .4V and

50mA at 1V on a transient basis. The 50mA is needed to

discharge the line capacitance. A 150½ resistor from the

line to Pin 11 limits the current into Pin 11 when the line

driver is on.

INPUTS:

1. Address inputs: Pin#'s 2,3,4,5,6.

The CS212 has 5 address inputs which decide what

address code it will respond to. Their thresholds are

approximately 1/2 VDD and draw less than 20µA. The

inputs should be grounded for Logic "0" and tied to VDD

(PIN 12) through a 10K resistor for Logic "1". The resis-

tor is necessary for non-destruction of the IC with 28V

applied to the line.

2. Data Inputs: Pin#'s 7,8.

IN0 and IN1 (Pins 8 and 7) are digital inputs and are

similar to the address inputs in that they have a thresh-

old of approximately 1/2 VDD. When the CS212 is unad-

dressed, these inputs draw less than 20µA. When the

circuit powers up, IN0 and IN1 typically source 400µA.

3. Detector Loop: Pin #'s 13, 14.

IN2 and IN3 can be used together to form a detector

loop. When used, the outputs are connected together

through a window foil and a diode. These inputs will

generate a logic Ò1Ó at D1 on the line when the pins are

shorted or opened.

When using IN2 and IN3, IN1 must be terminated to

VDD through the 10K Resistor used for the address

inputs. When using IN1, IN2 and IN3 must be shorted

or opened.

4. Line Input: Pin #9

The line input is internally connected to two compara-

tors. These comparators separate the line signal into

clock and data. The line input will draw less than 16µA

of input current.

5. VDD: Pin #12

The VDD Pin provides power to the CS212 circuitry. The

line signal is externally rectified and filtered, then

applied to VDD. The VDD pin draws varying amounts of

current, depending upon the state of the CS212. (See

specification). The unaddressed current is less than

0.8mA.

The operating voltage range is 10V to 18V on Pin 12 of

the IC. This wide range is necessary because of losses in

the line and ripple on VDD.

The circuit is designed to withstand 28V applied to the

line. This is to prevent the destruction of the IC and its

external components if the 2-wire cable is miswired.

IN 1

IN 2

IN 3

1 When IN 1=1

1 When Loop

is Open or Shorted

T0 D, Online

Durning Read

Loop Status

DET.

OUT 0, OUT 1, DSR

LINE

DSR

The Edge is Present

When OUT 0 & OUT 1 are Updated.

00 0

Data Parity

OUT 1

OUT 0

"1" for Write

Add Parity

A4=0 x 24 = 0

A3=0 x 23 = 0

A2=0 x 22 = 0

A1=1 x 21 = 2

A0=0 x 20 = 0

Binary = #2

A0 A1 A2 A3 A4 PA

WRITE

BIT

D0 D1 PD

Functional Description: continued

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