ISL54214_14 Datasheet, PDF (10/22 Pages) Intersil Corporation – USB 2.0 High-Speed x 2 Channels/Stereo Audio Dual SP3T (Dual 3 to 1 Multiplexer)

ISL54214
Application Block Diagrams
3.3V
USB
HIGH-SPEED
TRANSCEIVER
#2
AUDIO
CODEC
USB
HIGH-SPEED
TRANSCEIVER
#1
OR UART
TRANSCEIVER
2D-
2D+
L
R
1D-
1D+
V_DD
ISL54214
LOGIC CONTROL
C0
4MΩ ^C1
COM -
COM +
1kΩ
50kΩ
50kΩ
GND
1kΩ
µCONTROLLER
V_BUS
Detailed Description
The ISL54214 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 differential 3 to 1
multiplexer to select between two different USB
differential data signals and audio L and R stereo
signals. Its offered in tiny µTQFN and TQFN packages
for use in MP3 players, PDAs, cellphones, and other
personal media players.
A device consists of two 2.3Ω audio switches and four
6.2Ω USB switches. The audio switches can accept
signals that swing below ground. They were designed
to pass audio left and right stereo signals, that are
ground referenced, with minimal distortion. The USB
switches were designed to pass high-speed USB
differential data signals with minimal edge and phase
distortion.
The ISL54214 was specifically designed for MP3
players, personal media players and cellphone
applications that need to combine the stereo audio and
USB channels into a single shared connector, thereby
saving space and component cost. The Typical
application block diagram of this functionality is
previously shown.
The ISL54214 contains two logic control pins (C1 and
C0) that determine the state of the device. The part
has the following five states or modes of operation: All
SWITCHES OFF; USB1; USB2; Audio; and Audio Mute.
These states are discussed in detail in “Logic Control”
on page 11.
A detailed description of the various types of switches
is provided in the following sections.
10
Audio Switches
The two audio switches (L, R) are 2.3Ω switches that
can pass signals that swing below ground.
Over a signal range of ±1V (0.707V_RMS) with V_DD >
2.7V, these switches have an extremely low r_ON
resistance variation. They can pass ground referenced
audio signals with very low distortion (<0.05%
THD+N) when delivering 15.6mW into a 32Ω
headphone speaker load. See Figures 16, 17, 18, 19
and 20 THD+N performance curves.
Crosstalk between the L and R audio switches over the
frequency range of 20Hz to 20kHz when driving a 32Ω
load is < -88dB. These switches have excellent
off-isolation > 105dB over the audio band when
connected to 32Ω loads and 77dB when connected to
20kΩ loads (In Audio Mute mode). See Figures 21 and
22 in “Typical Performance Curves” section.
The audio drivers should be connected at the L and R
side of the switch (pins 2 and 3) and the speaker loads
should be connected at the COM side of the switch
(pins 7 and 8).
The audio switches are active (turned ON) whenever
the C1 and C0 logic pins are logic “1” (High).
USB Switches
The four USB switches (1D+, 1D-, 2D+, 2D-) are
6.2Ω 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 23 and 24 for the high-speed
eye pattern taken with the switch in the signal path.
FN6816.3
June 28, 2010