ISL54233IRTZ-T7A Datasheet, PDF (8/18 Pages) Intersil Corporation – Wideband Differential 3:1 Multiplexer

Application Block Diagram
USB
TRANSCEIVER
DIGITAL
VIDEO
UART
3D-
3D+
2D-
2D+
1D-
1D+
ISL54233
3.3V
100Ω
VDD
LOGIC CONTROL
C0
4MΩ ^C1
COM -
µCONTROLLER
VBUS
COM +
GND
ISL54233
AUDIO
CODEC
ISL54406
HEAD
PHONE
JACK
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
switches is from -1V to V_DD. The signal voltage at D- and D+
should not be allowed to exceed the V_DD voltage rail or go below
ground by more than -1V for normal operation.
Fault Protection and Power-Off Protection
However, in the event that the USB 5.25V V_BUS voltage were
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-,
2D+, 3D-, 3D+) to be driven up to 5.25V while the V_DD supply
voltage is in the range of 0V to 4.6V. This fault condition causes
no stress to the IC.
In addition, when V_DD is at 0V (ground) all switches are OFF and
the fault voltage is isolated from the other side of the switch
(Power-Off Protection).
When V_DD is in the range of 2.7V to 4.6V, the fault voltage will
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.
8
FN7918.0
December 21, 2011