SM5950AM

NIPPON PRECISION CIRCUITS INC.—11

System Reset (RSTN)

The SM5950AM must be reset if any of the following conditions occur during normal operation. A reset pulse

is a LOW-level pulse applied to RSTN, although the reset operation actually occurs on the rising edge of the

LOW-level pulse.

I

When the power supply is applied

A reset (RSTN = LOW to HIGH) is required when the power supply voltage is applied and after the LRCI,

BCKI, SCKO (and LRCO, BCKO if in slave mode) clocks have stabilized.

I

When the LRCI and BCKI clocks are interrupted

This occurs when the sampling frequency is switched, when clocks stop due to a condition in a previous stage,

when the LRCI, BCKI clocks are dynamically switched, or when otherwise the clocks are not continuous.

A reset (RSTN = LOW to HIGH) is required after the LRCI, BCKI clocks have stabilized.

I

When the SCKO (and LRCO, BCKO if in slave mode) clocks are interrupted

This occurs when the sampling frequency is switched, when clocks stop due to a condition in a previous stage,

when the SCKO, LRCO, BCKO clocks are dynamically switched, or when otherwise the clocks are not contin-

uous.

A reset (RSTN = LOW to HIGH) is required after the SCKO, LRCO, BCKO clocks have stabilized.

A reset pulse is required under these conditions because the conversion ratio calculated based on such non-con-

tinuous clocks will result in an incorrect conversion ratio, and hence the output data will have incorrect values.

Output state during reset interval

DOUT is tied LOW during the reset interval (refer to section "Direct Mute" for operation after the reset is

released). In master mode, the LRCO and BCKO clocks are also tied LOW.

Direct Mute (DMUTE)

Direct mute ON/OFF

Other mute operations

Direct mute also occurs at system reset.

DMUTE

Function

L

Audio data output starts from the next output word.

H

0 data is output from the next output word.

RSTN

Function

L

0 data is output from the next output word.

H

Computed data output starts after 8 output word cycles.