6-4

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1CSTi

Control ST-BUS In (TTL Input) - This ST-BUS interface pin accepts a serial input

stream which loads the Control Register.

The mode of operation of the

device, the bits in the Violation word, and, the resetting of Data Activity (DA) and

Scan Point output (SPo) are controlled by this register. The contents of the register

are updated once every ST-BUS frame when the interface is enabled.

2DSTi

Data ST-BUS In (TTL Input) - Accepts the 8 bits of TEM Data when the ST-BUS

interface is enabled.

3C2i

2.048 MHz Clock (TTL Input) - This is the input for the 2.048 MHz clock.

4

DSTo

ST-BUS Output (Three-State Output) - This is the 2.048 Mbps serial output for

theTEM encoded word. It is enabled when both F1i and CA are low.

5F1i

Framing Type 1 Input (TTL Input) - This active low input, in conjunction with CA,

enables the ST-BUS interface (DSTi, DSTo and CSTi). It is internally sampled on

every positive edge of the C2i clock and provides frame synchronization.

6CA

Control Address (TTL Input) - This active low input (in conjunction with F1i)

enables the ST-BUS interface.

7DF

Data Format Select (CMOS Input) - When HIGH, the Data Codec accepts and

delivers the data in unipolar Return to Zero (RZ) format. When LOW, the data

format is unipolar NRZ.

8RxE

Received Energy Signal (Schmitt Input) - When RxE goes LOW it establishes the

last pulse before RxE goes LOW is established as the unipolar MARK input. RxE

also enables the operation of DA and SPo outputs the loopback modes (Modes 4, 5

and 6) of the codec, RxE is forced to the LOW state internally independent of the pin

condition. RxE should be exerted LOW for the duration of a data call.

Data Transmit 1 (Schmitt Input) - If DF= LOW, accepts data in the NRZ format.

(HIGH = MARK, LOW = SPACE).

If DF=HIGH, accepts active low unipolar pulses representing the digital data in the

RZ format. MARK or SPACE polarity is established by the RxE input.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

24

23

22

21

20

19

18

17

CSTi

DSTi

C2i

DSTo

F1i

CA

DF

RxE

DX1

DX2

NRZo

VSS

VDD

NC

PRST

NC

NC

DR1

DR2

DA

SPo

SPi

DP

SCLK