ISL54217IRTZ Intersil, ISL54217IRTZ Datasheet - Page 13

• Manufacturer Part Number: ISL54217IRTZ
• Description: IC USB SWITCH DUAL SP3T 12TQFN
• Manufacturer: Intersil

Specifications of ISL54217IRTZ

• Function: USB Switch
• Circuit: 2 x SP3T
• On-state Resistance: 8 Ohm
• Voltage Supply Source: Single Supply
• Voltage - Supply, Single/dual (±): 2.7 V ~ 4.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 12-TQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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)
13
ISL54217
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. Any signals connected at the USB2 signal
lines will momentarily get passed through to the COM
outputs.
Delay time between C1 and C0 must be <100ns and
should be controlled by logic control drivers with well
behaved monotonic transitions from High to Low and Low
to High and with typical logic family rise and fall times of
1ns to 6ns.
POWER
The power supply connected at VDD (pin 11) provides
power to the ISL54217 part. Its voltage should be kept in
the range of 2.7V to 4.6V. In a typical application, V
will be in the range of 2.7V to 4.3V and will be connected
to the battery or LDO of the MP3 player or cellphone.
A 0.01µF or 0.1µF decoupling capacitor should be
connected from the VDD pin to ground to filter out any
power supply noise from entering the part. The capacitor
should be located as close to the VDD pin as possible.
Before power-up and power-down of the ISL54217 part,
the C1 and C0 control pins should be driven to ground or
tri-stated. This will put the switch in the ALL SWITCHES
OFF state, which turns all switches OFF and activate the
click and pop circuitry. This will minimize transients at the
speaker loads during power-up and power-down of the
ISL54217 device. See Figure 32 in the “Typical
Performance Curves” section.
AC COUPLED CLICK AND POP OPERATION
Single supply audio drivers have their signal biased at a DC
offset voltage, usually at 1/2 the DC supply voltage of the
driver. As this DC bias voltage comes up or goes down
during power-up or power-down of the driver, a transient
can be coupled into the speaker load through the DC
blocking capacitor (see the “Block Diagram” on page 11).
When a driver is OFF and suddenly turned ON the rapidly
changing DC bias voltage at the output of the driver will
cause an equal voltage at the input side of the switch due
to the fact that the voltage across the blocking capacitor
cannot change instantly. If the switch is in the Audio
mode or there is no low impedance path to discharge the
blocking capacitor voltage, before turning the audio
switch ON, a transient discharge will occur in the speaker,
generating a click/pop noise.
Proper elimination of a click/pop transient at the speaker
loads while powering up or down of the audio drivers
requires that the ISL54217 have its click/pop circuitry
activated by putting the part in the ALL SWITCHES OFF
mode. This allows the transients generated by the audio
drivers to be discharged through the click and pop shunt
circuitry.
June 17, 2010
FN6817.4
DD