MT9126

Preliminary Information

8-34

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1

EN1

Enable Strobe 1 (Output). This 8 bit wide, active high strobe is active during the B1

PCM channel in ST-BUS mode. Becomes a single bit, high true pulse when LINEAR=1.

In SSI mode this output is high impedance.

2

MCLK

Master Clock (input). This is a 4.096 MHz (minimum) input clock utilized by the

transcoder function; it must be supplied in both ST-BUS and SSI modes of operation.

In ST-BUS mode the C4 ST-BUS clock is applied to this pin. This synchronous clock is

also used to control the data I/O flow on the PCM and ADPCM input/output pins

according to ST-BUS requirements.

In SSI mode this master clock input is derived from an external source and may be

asynchronous with respect to the 8 kHz frame. MCLK rates greater than 4.096 MHz are

acceptable in this mode since the data I/O rate is governed by BCLK.

3F0i

Frame Pulse (Input). Frame synchronization pulse input for ST-BUS operation. SSI

4

C2o

2.048 MHz Clock (Output). This ST-BUS mode bit clock output is the MCLK (C4) input

divided by two, inverted, and synchronized to F0i. This output is high-impedance during

SSI operation.

5

BCLK

Bit Clock (Input). 128 kHz to 4096 kHz bit clock input for both PCM and ADPCM ports;

used in SSI mode only. The falling edge of this clock latches data into ADPCMi, PCMi1

and PCMi2. The rising edge clocks data out on ADPCMo, PCMo1 and PCMo2. This input

6

PCMo1

Serial PCM Stream 1 (Output). 128 kbit/s to 4096 kbit/s serial companded/linear PCM

output stream. Data are clocked out by rising edge of BCLK in SSI mode. Clocked out by

MCLK divided by two in ST-BUS mode. See Figure 14.

7

PCMi1

Serial PCM Stream 1 (Input). 128 kbit/s to 4096 kbit/s serial companded/linear PCM

input stream. Data are clocked in on falling edge of BCLK in SSI mode. Clocked in at the

3/4 bit position of MCLK in ST-BUS mode. See Figure 14.

Digital Ground. Nominally 0 volts.

9

LINEAR

bit linear PCM. Linear PCM operates only at a bit rate of 2048 kbit/s. Companded PCM is

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

28

27

26

25

24

23

22

21

MS1

VDD

MS3

IC

MS4

FORMAT

MS2

PWRDN

ADPCMi

ADPCMo

MS5

MS6

EN2

PCMo1

BCLK

PCMi1

LINEAR

ENB2/F0od

VSS

C2o

MCLK

F0i

PCMi2

ENB1

PCMo2

EN1

SEL

A/

µ