ISL54200

9

FN6408.2

June 17, 2010

Application Block Diagram

Detailed Description

The ISL54200 device is a dual single pole/double throw

(SPDT) analog switch that operates from a single DC

power supply in the range of 2.7V to 5.5V. It was

designed to function as a dual 2-to-1 multiplexer to

select between a USB high-speed transceiver and a USB

full-speed transceiver in portable battery powered

products. It is offered in a TDFN package and a small

µTQFN package for use in MP3 players, cameras, PDAs,

cellphones, and other personal media players. The device

has an enable pin to open all switches.

The part consists of two 7Ω full speed (FSx) switches and

two 4.5Ω high speed (HSx) switches. The FSx switches

USB full speed (12Mbps) differential data signals with

minimal distortion. The HSx switches have high

bandwidth and low capacitance to pass USB high-speed

(480Mbps) differential data signals with minimal edge

and phase distortion.

The ISL54200 was designed for MP3 players, cameras,

cellphones, and other personal media player applications

that have both high-speed and full-speed transceivers

and need to multiplex between these USB sources to a

single USB host (computer). A typical application block

diagram of this functionality is shown on page 9.

A detailed description of the two types of switches are

provided in the following sections.

FSx Switches (FSD1, FSD2)

The two FSx switches (FSD1, FSD2) are bidirectional

switches that can pass rail-to-rail signals. When powered

resistance of 7Ω over the signal range of 0V to 3.3V. They

were specifically designed to pass USB full-speed

(12Mbps) differential signals and meet the USB 2.0 full-

speed signal quality specifications. See Figure 8.

The FSx switches can also pass USB high speed signals

(480Mbps) but do not quite meet the USB 2.0 high speed

signal quality eye diagram compliance requirement.

The maximum signal range for the FSx switches is from

than -1.5V.

When operated with a 2.7V to 3.6V supply, the FSx

switches are active (turned ON) whenever the IN logic

HSx Switches (HSD1, HSD2)

The two HSx switches (HSD2, HSD1) are bi-directional

switches that can pass rail-to-rail signals. When powered

and HSD2 switches over this signal range is only 0.01Ω,

ensuring minimal impact by the switches to USB high

speed signal transitions. As the signal level increases, the

the switch resistance is nominally 20Ω.

The HSx switches were specifically designed to pass USB

2.0 high-speed (480Mbps) differential signals typically in

the range of 0V to 400mV. They have low capacitance

and high bandwidth to pass the USB high-speed signals

with minimum edge and phase distortion to meet USB

2.0 high speed signal quality specifications. See Figures 9

and 10.

The HSx switches can also pass USB full-speed signals

(12Mbps) with minimal distortion and meet all the USB

PORTABLE MEDIA DEVICE

ISL54200

USB

TRANSCEIVER

HIGH-SPEED

COMD1

COMD2

IN

GND

HSD1

HSD2

FSD1

FSD2

VDD

EN

LOGIC

µCONTROLLER

4MΩ

USB

TRANSCEIVER

FULL-SPEED

VBUS

D-

D+

GND

3.3V

ISL54200