LC75348 データシートの表示（PDF） - SANYO -> Panasonic

部品番号

コンポーネント説明

メーカー

LC75348

Single-Chip Electronic Volume and Tone Control System

SANYO -> Panasonic 

LC75348, 75348M

Usage Notes

• The internal transistor states are undefined when power is first applied. Applications must mute the output until control

data has been written to the IC.

• Operational description of the zero cross switching circuit

The LC75348 and LC75348M provide a function that can switch the zero cross comparator signal detection point,

allowing applications to select an optimal detection point for the block whose data is being updated. Basically,

switching noise can be minimized if the signal immediately following the block whose data is updated is input to the

zero cross comparator. This means that the detection point must be switched each time data is updated.

Selector

Volume

Tone controls

Switch

Zero cross

comparator

LC75348 and LC75348M Zero Cross Detection Circuit

• Zero cross switching control procedure

The zero cross switching control procedure consists of three steps. First, set the zero cross control bit to zero cross

detection mode (D25 = 0), then specify the block for detection (with bits D28 and D29), and finally transfer the data.

Since these control bits are latched first, immediately after the data is transferred, i.e. on the CE falling edge, the mode

can be set in a single data transfer operation when updating the volume control or other control block data. The figure

below presents an example of the control used when updating the volume control block data.

D25

D28

D29

0

1

0

Zero cross detection

mode setting

Volume control

block setting

No. 7308 -17/21

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