isl54214 Intersil Corporation, isl54214 Datasheet - Page 9

• Manufacturer Part Number: isl54214
• Description: Usb 2.0 High-speed X 2channels/stereo Audio Dual Sp3t Dual 3 To 1 Multiplexer
• Manufacturer: Intersil Corporation

Application Block Diagrams
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 10.
TRANSCEIVER
TRANSCEIVER
TRANSCEIVER
HIGH-SPEED
HIGH-SPEED
CODEC
AUDIO
UART
USB
USB
# 1
# 2
or
9
2D-
2D+
1D-
1D+
L
R
50kΩ
ISL54214
GND
LOGIC CONTROL
ISL54214
VDD
50kΩ
3.3V
A detailed description of the various types of switches are
provided in the following sections.
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
these switches have an extremely low R
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, 22, and 23 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
1kΩ
4MΩ
COM -
COM +
1kΩ
C0
C1
±
µCONTROLLER
1V (0.707Vrms) with VDD > 2.7V,
V
BUS
ON
resistance
December 11, 2008
FN6816.0