ISL54217_14 Datasheet, PDF (12/24 Pages) Intersil Corporation – USB 2.0 High-Speed x 2 Channels/Stereo Audio Dual SP3T (Dual 3-to-1 Multiplexer)

ISL54217
eliminating click and pop noise in the headphones. See
the “AC COUPLED CLICK AND POP OPERATION” on
page 13.
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 27 and 28 for High-speed Eye
Pattern taken with switch in the signal path.
These switches can also swing rail to rail and pass USB
full-speed signals (12Mbps) with minimal distortion. See
Figure 29 for Full-speed Eye Pattern taken with 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 allow to exceed the V_DD voltage rail or
go below ground by more than -1V for normal operation.
However, in the event that the USB 5.25V V_BUS voltage
were shorted to one or both of the COM pins, the
ISL54217 has fault protection circuitry to prevent
damage to the ISL54217 part. The fault circuitry allows
the signal pins (COM-, COM+, 1D-, 1D+, 2D-, 2D+, L
and R) 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. 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.
The USB (1D+ and 1D-) switches are active (turned ON)
whenever the C1 is logic “0” (Low) and C0 is logic “1”
(High). The USB (2D+ and 2D-) switches are active
(turned ON) whenever the C1 is logic “1” (High) and C0
is logic “0” (Low) provided the last state was not the
Audio or Audio Mute state.
ISL54217 Operation
The discussion that follows will discuss using the
ISL54217 in the “Block Diagram” on page 11.
LOGIC CONTROL
The state of the ISL54217 device is determined by the
voltage at the C1 pin (pin 9) and the C0 pin (pin 10). The
part has five states or modes of operation. The All
SWITCHES OFF mode, USB1 mode, USB2 mode, Audio
mode and Audio Mute mode. Refer to “Truth Table” on
page 3 and “State Diagram” on page 2 of data sheet.
The C1 pin and C0 pin are internally pulled low through
4MΩ resistors to ground and can be tri-stated or left
floating.
The C1 pin and C0 pin can be driven with a voltage that
is higher than the V_DD supply voltage. They can be
driven up to 5.25V with the V_DD supply in the range of
2.7V to 4.6V. Driving the logic higher than the supply rail
will cause the logic current to increase. With V_DD = 2.7V
and V_LOGIC = 5.25V, I_LOGIC current is approximately
5.5µA.
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 13.
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).
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FN6817.4
June 17, 2010