9

FN6318.1

June 27, 2006

Application Block Diagram

Detailed Description

The ISL5441X family of devices are dual single pole/double

throw (SPDT) analog switches that operate from a single

power supply. They were designed to function as dual 2 to 1

multiplexers to select between USB differential data signals

and mono Audio/Composite Video Broadcast System

(CVBS). They come in tiny µTQFN package for use in digital

cameras, camcorders, video MP3 players, PDAs,

cellphones, and other personal media players.

All devices in this family consist of two 1

Ω normally closed

(NC) Audio/Video switches and two 5

Ω normally open (NO)

USB switches. The audio/video switches can accept signals

that swing below ground. They were designed to pass

ground reference audio or DC-restored with synch

composite video signals with minimal distortion. The USB

switches were designed to pass full-speed USB differential

data signals with minimal edge and phase distortion.

The ISL54415 and ISL54416 were specifically designed for

digital cameras, camcorders, MP3 players, cellphones and

other personal media player applications that need to

combine the audio/video jacks and the USB data connector

into a single shared connector, thereby saving space and

component cost. A typical application block diagram of this

functionality is shown above. The ISL54415 and ISL54416

voltage, which is used to switch between the audio/video

drivers and USB transceiver of media player. The ISL54415

contains additional circuitry to generate the required USB

resistor.

The ISL54417 is an audio/video and data switch who’s logic

control is typical of a standard dual SPDT device.

A detailed description of the two types of switches and of

each part type in the ISL5441X family are provided in the

following sections. The digital data transmission (USB, etc.)

and audio/video playback are intended to be mutally

exclusive operations.

NC1 and NC2 Audio/Video Switches

The two NC (normally closed) audio/video switches (NC1,

NC2) are 1

Ω high bandwidth switches that can pass signals

that swing below ground by as much as 1.5V. They were

design to pass ground reference audio signals and

DC-restored Composite Video Broadcast System (CVBS)

including negative synchronizing pulse with minimal

insertion loss and very low distortion and degradation.

The -3dB bandwidth into 50

Ω is 394MHz and into 75Ω is

264MHz. Crosstalk between NC1 and NC2 @ 4MHz is

-60dB which allows composite video to be routed through

one switch and mono-audio through the other switch with

little interference.

The recommended maximum signal range is from -1.5V to

1.5V. You can apply positive signals greater than 1.5V but

rail or swing more negative than -1.5V.

Over a signal range of ±1V these switches have an

referenced audio signal with very low distortion (<0.007%

THD+N) when delivering 12mW into a 32

Ω headphone

speaker load. See Figures 10 and 11 THD+N performance

curves.

Figures 8 and 9 show the vector scope plots of a standard

NTSC color bar signal at both the input (Figure 8) and output

(Figure 9) of the ISL54415. The plots show that except for a

there is virtually no degradation of the video waveform

through the switch.

ISL54415

USB

TRANSCEIVER

FULL-SPEED

AUDIO

COM1

COM2

GND

NO1

NO2

NC1

NC2

NTSC OR PAL

VIDEO

D-

D+

ISL54415, ISL54416, ISL54417