ISL54217_09 Datasheet, PDF (11/21 Pages) Intersil Corporation – USB 2.0 High-Speed x 2Channels/Stereo Audio Dual SP3T (Dual 3-to-1 Multiplexer)

ISL54217
Logic Control Voltage Levels
With VDD in the range of 2.7V to 3.6V the logic levels are:
C1, C0 = Logic “0” (Low) when ≤ 0.5V or Floating.
C1, C0 = Logic “1” (High) when ≥ 1.4V
ALL SWITCHES OFF Mode
If the C1 pin = Logic “0” and C0 pin = Logic “0” the part will
be in the ALL SWITCHES OFF mode. In this mode the 2D-
and 2D+ USB switches, the L and R audio switches and the
1D- and 1D+ USB switches will be OFF (high impedance).
The audio click and pop shunt circuitry will be activated (ON)
and the 1kΩ COM shunt resistors will be disconnected
(OFF).
Before powering down or powering up of the audio CODECs
drivers the ISL54217 should be put in the ALL SWITCHES
OFF mode. In this mode transients present at the L and R
signal pins due to the changing DC voltage of the audio
drivers will not pass to the headphones, preventing clicks
and pops in the headphones. See the “AC Coupled click and
pop operation” on page 12.
It is recommended that when transitioning from USB1 to
USB2 or from USB2 to USB1 that you always pass through
the All Switches OFF state.
Audio Mode
If the C1 pin = Logic “1” and C0 pin = Logic “1” the part will
be in the Audio mode. In Audio mode the L (left) and R (right)
2.3Ω audio switches are ON. The 1D- and 1D+ 6.2Ω USB
switches and 2D- and 2D+ 6.2Ω USB switches will be OFF
(high impedance).
The audio click and pop circuitry is de-activated. The 1kΩ
shunts on the COM side of the switch will be disconnected
(OFF).
When a headphone is plugged into the common connector,
the µcontroller will drive the C1 and C0 logic pins “High”
putting the part in the audio mode. In the audio mode, the
audio drivers of the player can drive the headphones and
play music.
USB1 Mode
If the C1 pin = Logic “0” and C0 pin = Logic “1” the part will
go into USB1 mode. In USB1 mode the 1D- and 1D+ 6.2Ω
switches are ON. The L and R 2.3Ω audio switches and 2D-
and 2D+ 6.2Ω USB switches will be OFF (high impedance).
The audio L and R click and pop shunt circuitry will be
activated and the 1kΩ COM shunt resistors will be
disconnected (OFF).
When a USB cable from a computer or USB hub is
connected at the common connector, the µcontroller will
route the incoming USB signal to USB transceiver section #1
by taking the C1 pin “Low” and the C0 pin “High” putting the
ISL54217 part into the USB1 mode. In USB1 mode the
computer or USB hub transceiver and the MP3 player or
cellphone USB transceiver #1 are connected and digital data
will be able to be transmit back and forth.
USB2 Mode
If the C1 pin = Logic “1” and C0 pin = Logic “0” the part will
be in the USB2 mode provided that the last state was not the
Audio or Audio Mute state. In the USB2 mode the 2D- and
2D+ 6.2Ω USB switches will be ON and audio switches and
the 1D- and 1D+ USB switches will be OFF (high
impedance).
The audio L and R click and pop shunt circuitry will be
activated and the 1kΩ COM shunt resistors will be
disconnected (OFF).
When a USB cable from a computer or USB hub is
connected at the common connector, the μcontroller will
route the incoming USB signal to USB transceiver section #2
by taking the C1 pin “High” and the C0 pin “Low” putting the
ISL54217 part into the USB2 mode. In USB2 mode the
computer or USB hub transceiver and the MP3 player or
cellphone USB transceiver #2 are connected and digital data
will be able to be transmit back and forth.
Audio MUTE Mode
If the C1 pin = Logic “1” and C0 pin = Logic “0” the part will
be in the Audio MUTE mode provided that the last state was
the Audio state. In the audio MUTE mode the 2D- and 2D+
USB switches, the L and R audio switches and the 1D- and
1D+ USB switches will be OFF (high impedance).
The audio click and pop shunt circuitry will be de-activated
and the 1kΩ COM shunt resistors will be connected (ON).
Note: 1kΩ COM shunt resistors are only ON when in Audio
MUTE mode.
The 1kΩ shunts provide 77dB of off-isolation when driving
10kΩ to 20kΩ amplifier inputs.
Logic Control Timing Between C1 and C0
The ISL54217 has a unique logic control architecture. The
part has five different logic states but only two external logic
control pins, C1 and C0. Refer to “State Diagram” on page 2
and “Truth Table” on page 3.
The following state transitions require both C1 and C0 logic
control bits to change their logic levels in unison:
All OFF(C1 = 0, C0 = 0) -----> Audio (C1 = 1, C0 =1)
Audio (C1 = 1, C0 = 1) -----> All OFF (C1 = 0, C0 = 0)
Audio Mute (C1 = 1, C0 = 0) -----> USB1 (C1 = 0, C0 = 1)
The delay time between transition of these bits must be
< 100ns to ensure that you directly move between these
states without momentarily transitioning to one of the other
states.
For example, if you are going from the “All OFF” state to the
“Audio” state and C0 does not go high until 100ns after C1
went high you will momentarily transition to the “USB2” state.
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FN6817.3
May 4, 2009