Preliminary Information MT9126
8-35
10 ENB2/F0od PCM B-Channel Enable Strobe 2 (Input) / Delayed Frame Pulse (Output).
SSI operation: ENB2 (Input). An 8-bit wide enable strobe input defining B2 channel
(AD)PCM data. A valid 8-bit strobe must be present at this input for SSI operation. See
Figures 4 & 6.
ST-BUS operation: F0od
(Output). This pin is a delayed frame strobe output. When LIN-
EAR=0, this becomes a delayed frame pulse output occurring 64 C4
clock cycles after
F0i
and when LINEAR = 1 at 128 C4 clock cycles after F0i . See Figures 7, 8, 9 & 14.
11 ENB1 PCM B-Channel Enable Strobe 1 (Input).
SSI operation: An 8-bit wide enable strobe input defining B1 channel (AD)PCM data. A
valid 8-bit strobe must be present at this input for SSI operation.
ST-BUS operation: When tied to V
SS
transparent bypass of the ST-BUS D- and C- chan-
nels is enabled. When tied to V
DD
the ST-BUS D-channel and C-channel output timeslots
are forced to a high-impedance state.
12 PCMo2 Serial PCM Stream 2 (Output). 128 kbit/s to 4096 kbit/s serial companded/linear PCM
output stream. Clocked out by rising edge of BCLK in SSI mode. Clocked out by MCLK
divided by two in ST-BUS mode. See Figure 14.
13 PCMi2 Serial PCM Stream 2 (Input). 128 kbit/s to 4096 kbit/s serial companded/linear PCM input
stream. Data bits 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.
14 SEL SELECT (Input).
PCM bypass mode: When SEL=0 the PCM1 port is selected for PCM bypass operation
and when SEL=1 the PCM2 port is selected for PCM bypass operation.
See Figures 6 & 9.
16 kbit/s transcoding mode:
SSI Operation - in 16 kbit/s transcoding mode, the ADPCM words are assigned to the I/O
timeslot defined by ENB2 when SEL=1 and by ENB1 when SEL=0. See Figure 4.
ST-BUS operation- in 16 kbit/s transcoding mode, the ADPCM words are assigned to the
B2 timeslot when SEL=1 and to the B1 timeslot when SEL=0. See Figure 9.
15 A/µ
A-Law/µ−Law Select (Input). This input pin selects µ−Law companding when set to
logic 0, and A-Law companding when set to logic 1. This control is for all channels .This
input is ignored in Linear mode during which it may be tied to V
SS
or V
DD
.
16 FORMAT FORMAT Select (Input). Selects ITU-T PCM coding when high and Sign-Magnitude
PCM coding when low. This control is for all channels.This input is ignored in Linear
mode during which it may be tied to V
SS
or V
DD
.
17 PWRDN
Power-down (Input). An active low reset forcing the device into a low power mode
where all outputs are high-impedance and device operation is halted.
18 IC Internal Connection (Input). Tie to V
SS
for normal operation.
Pin Description
Pin # Name Description
