PT2318 Просмотр технического описания (PDF) - Princeton Technology

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PT2318

Sound Fader Controller IC

Princeton Technology 

Tel: 886-2-66296288

Fax: 886-2-29174598

URL: http://www.princeton.com.tw

Sound Fader Controller IC

MUTE

PT2318 provides three mute modes namely:

1. Zero Crossing Mode via the I2C bus using 2 independent zero crossing detectors.

2. Fast Mute via Mute Pin

3. Fast Mute via I2C Bus either by General Mute (GMU) or by Volume 2 Block Setting.

PT2318

The following table shows the setting for the Zero Crossing Mode and the General Mute Mode

GMU

0

0

1

1

ZCM

0

1

0

1

Function

Direct MUTE off

MUTE off delayed until the next Zero Crossing

Direct MUTE

MUTE delayed until the next Zero Crossing

Notes:

1. GMU=General Mute Bit (Mute control for all outputs)

2. ZCM=Zero Crossing Mode Bit

The mute function is immediately performed if the ZCM=“0”. If ZCM=”1”, the mute is activated after

changing the GMU bit. The actual mute switching is delayed until the next zero crossing of the audio

frequency signal. The left and right audio channels are independent of each other, therefore, there are

two built-in comparators controlling the independent mute switches. In order to avoid too much delay in

mute switching when very low frequencies are processed, the maximum delay time is limited to a

typical value of 100ms by an integrated timing circuit and an external capacitor. This timing circuit is

triggered by the reception of a new data word for the switch function (including a GMU bit). After an

external capacitor is discharged and charged, the muting switch follows the GMU bit if there was no

zero crossing detected during that particular time.

Externally controlling the mute function is possible. If the mute pin is set to Ground, all outputs are

muted immediately (this is the hardware mute.). Please refer to the diagram below.

PT2318

HARDWARE

MUTE SWITCH

12 MUTE

The mute request overwrites all mute controls via the I2C bus for the time the pin is held at “LOW” level.

The hardware mute function is ideal for Radio Data System applications. The zero crossing mute

avoids modulation plops. This feature is advantageous when the changing presets and/or sources.

PT2318 V1.2

- 18 -

March, 2006

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