ISO-CMOS

MT8950

6-5

10

Data Transmit 2 (Schmitt Input) - If DF = LOW, accepts data pulses which are

restrictions on the use of this input is explained in the text.

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.

11

NRZo

Non-Return to Zero Output (Open Drain Output) - The incoming data, in the RZ

format or the NRZ format , is internally converted to inverted NRZ and appears on

this open drain output. This output in conjunction with the SPi input can be used for

long space detection.

12

Ground (0 Volt).

13

SCLK

Secondary Clock (TTL Input) - This is an external clock input that determines the

timing of the Violation Word and the synchronization pulses. If these features are

14

DP

Drive Point Output (Totem-pole Output) - This output is exerted high when the

Control Register bits b7, b6 and b5 are set to 110 (decimal 6). The operation of the

Codec is normal in every other respect.

15

SPi

Uncommitted Scan Point Input (Voltage Comparator Input ) - A LOW to HIGH

transition on this input causes SPo to be set LOW. This is used to detect a long

SPACE condition in conjunction with NRZo (pin 11).

16

SPo

Uncommitted Scan Point Output (Totem-pole Output ) - This output is set LOW

when the SPi input undergoes a LOW to HIGH transition. The SPo is reset by the

presence of a logic "1" in bit b0 of Control Register. This function is active at all

times except when RxE is false and during power reset conditions.

17

DA

Data Activity (Totem-pole Output ) - The NRZ/RZ input circuitry monitors the

input signal (after polarity is established) and activates this output when it detects a

SPACE on the input. This output is reset by the presence of a logic "1" in bit 1 of the

Control Register. The DA function is active at all times except when RxE is false and

during power reset conditions.

18

Data Receive 2 (Totem-pole Output) - If DF = LOW ( NRZ format), outputs the

secondary data signal in the NRZ form as explained in the text.

If DF = HIGH (RZ format), outputs unipolar, active high MARK pulses.

19

Data Receive 1 (Totem-pole Output) - If DF = LOW (NRZ format) , outputs the

NRZ data signal. ( HIGH = MARK, LOW = SPACE)

If DF = HIGH (RZ format), outputs unipolar, active low SPACE pulses.

20

NC

No connection.

21

NC

No connection.

22

PRST

Power Reset (CMOS Schmitt Input ) - A LOW level on this input evokes the power

reset condition for the codec.

23

NC

No connection.

24

Positive Supply Voltage +5 volts ± 10% .

Pin Description (continued)

Pin #

Name

Description