ISL54233

8

FN7918.0

December 21, 2011

Application Block Diagram

Detailed Description

The ISL54233 device consists of dual SP3T (single pole/triple

throw) analog switches. It operates from a single DC power

supply in the range of 2.7V to 4.6V. It was designed to function as

a differential 3 to 1 multiplexer to select between three different

differential data signals. It is offered in tiny UTQFN and TQFN

packages for use in MP3 players, PDAs, cellphones, and other

personal media players.

The device consists of six 6Ω data switches. It was designed to

pass high-speed USB differential data and digital video signals

with minimal edge and phase distortion. It can swing rail-to-rail to

pass UART and full-speed USB signals.

The COM pins can accept signals that swing below ground by as

much as -2V. This allows an audio source to be wired-OR

connected at the COM pins.

The ISL54233 was specifically designed for MP3 players,

personal media players and cellphone applications that need to

combine three differential data channels into a single shared

connector, thereby saving space and component cost. This

functionality is shown in the Typical Application Block Diagram

on page 1.

A detailed description of the switches is provided in the following

sections.

Data Switches

The six data switches (1D+, 1D-, 2D+, 2D-, 3D+, 3D-) are 6Ω

bidirectional switches that were specifically designed to pass

high-speed USB differential data signals in the range of 0V to

400mV. The switches have low capacitance and high bandwidth

to pass USB high-speed signals (480Mbps) with minimum edge

and phase distortion to meet USB 2.0 signal quality

specifications. See Figures 15 and 16 for high-speed Eye Pattern

taken with the switch in the signal path.

These switches can also swing rail-to-rail and pass USB full-speed

(12Mbps) and UART signals with minimal distortion. See

Figure 17 for USB full-speed Eye Pattern taken with the switch in

the signal path.

The maximum normal operating signal range for the USB

ground by more than -1V for normal operation.

Fault Protection and Power-Off Protection

shorted to one or both of the COM pins, the ISL54233 has fault

protection circuitry to prevent damage to the ISL54233 part. The

fault circuitry allows the signal pins (COM-, COM+, 1D-, 1D+, 2D-,

voltage is in the range of 0V to 4.6V. This fault condition causes

no stress to the IC.

the fault voltage is isolated from the other side of the switch

(Power-Off Protection).

pass through to the output of an active switch channel.

Note: During the fault condition, normal operation is not

guaranteed until the fault condition is removed.

ISL54233 Operation

The discussion that follows will discuss using the ISL54233 in the

“Application Block Diagram” on page 8.

ISL54233

DIGITAL

VIDEO

UART

COM -

COM +

C1

GND

1D+

1D-

2D+

2D-

VDD

C0

LOGIC CONTROL

µCONTROLLER

VBUS

3.3V

3D-

USB

4MΩ

TRANSCEIVER

3D+

AUDIO

CODEC

ISL54406

HEAD

PHONE

JACK

100Ω