ISL54210 Datasheet, PDF (12/21 Pages) Intersil Corporation – MP3/USB 2.0 High Speed Switch with Negative Signal Handling/Click and Pop Suppression

ISL54210
USB Switches
The two USB switches (D+, D-) are 5.5Ω bidirectional
switches that were specifically designed to pass
high-speed USB differential signals typically 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 Figure 20
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 21 for full-speed eye pattern taken with switch in
the signal path.
The maximum signal range for the USB switches is from
-1.5V to V_DD. The signal voltage at D- and D+ should not
be allowed to exceed the V_DD voltage rail or go below
ground by more than -1.5V.
The USB switches are active (turned ON) whenever the
V_BUS voltage is ≥ to V_DD + 0.8V. V_BUS is internally pulled
low, so when V_BUS is floating the USB switches are OFF.
ISL54210 Operation
The following discusses using the ISL54210 in the
“Typical Application Block Diagram” on page 11.
V_DD SUPPLY
The DC power supply connected at V_DD (Pin 10 for
µTQFN, Pin 1 for TDFN) provides the required bias
voltage for proper switch operation. Its voltage should be
kept in the range of 2.7V to 3.6V when used in a
USB/Audio application to ensure you get proper
switching when the V_BUS voltage is at its lower limit of
4.4V.
In a typical USB/Audio application for portable battery
powered devices, the V_DD voltage will come from a
battery or an LDO and be in the range of 2.7V to 4.3V.
For best possible USB full-speed operation (12Mbps), it is
recommended that the V_DD voltage be ≥2.7V in order to
get a USB data signal level above 2.7V.
Before power-up and power-down of the ISL54210 part,
the V_BUS and CTRL control pins should be driven to
ground or tri-stated. This will put the switch in the mute
state which turns all switches OFF and activates the click
and pop circuitry. Which will minimize transients at the
speaker loads during power-up and power-down.
LOGIC CONTROL
The state of the ISL54210 device is determined by the
voltage at the V_BUS pin (Pin 1 for µTQFN, Pin 2 for TDFN)
and the CTRL pin (Pin 9 for µTQFN, Pin 10 for TDFN). The
part has three states or modes of operation: Audio Mode,
USB Mode and Mute Mode. Refer to the “Truth Table” on
page 2.
The V_BUS pin and CTRL pin are internally pulled low
through 4MΩ resistors to ground and can be left floating
or tri-stated. The CTRL control pin is only active when
V_BUS is logic “0”.
Logic Control Voltage Levels:
V_BUS = Logic “0” (Low) when V_BUS ≤ V_DD + 0.2V or
Floating.
V_BUS = Logic “1” (High) when V_BUS ≥ V_DD + 0.8V
CTRL = Logic “0” (Low) when ≤ 0.5V or Floating.
CTRL = Logic “1” (High) when ≥ 1.4V
Audio Mode
If the V_BUS pin = Logic “0” and CTRL pin = Logic “1”, the
part will be in the Audio mode. In Audio mode, the L
(left) and R (right) 2.5Ω audio switches are ON, the D-
and D+ 5.5Ω switches are OFF (high impedance) and the
audio click and pop circuitry is OFF (high impedance).
In a typical application, V_DD will be in the range of 2.7V
to 3.6V and will be connected to the battery or LDO of
the MP3 player or cellphone. When a headphone is
plugged into the common connector, nothing gets
connected at the V_BUS pin (its internally pulled low) and
as long as the CTRL = Logic “1” the ISL54210 part
remains in the audio mode and the audio drivers of the
player can drive the headphones and play music.
USB Mode
If the V_BUS pin = Logic “1” and CTRL pin = Logic “0” or
Logic “1” the part will go into USB mode. In USB mode,
the D- and D+ 5.5Ω switches are ON and the L and R
2.5Ω audio switches are OFF (high impedance).
When a USB cable from a computer or USB hub is
connected at the common connector, the voltage at the
V_BUS pin will be driven with the USB VBUS voltage which
will be in the range of 4.4V to 5.25V. The ISL54210 part
will go into the USB mode. In USB mode, the computer
or USB hub transceiver and the MP3 player or cellphone
USB transceiver are connected and digital data will be
able to be transmitted back and forth.
When the USB cable is disconnected the ISL54210
automatically turns the D+ and D- switches OFF.
Mute Mode
If the V_BUS pin = Logic “0” and CTRL pin = Logic “0”, the
part will be in the Mute mode. In the Mute mode, the
audio switches and the USB switches are OFF (high
impedance) and the audio click and pop circuitry is ON.
Before powering down or powering up of the audio
CODECs drivers, the ISL54210 should be put in the Mute
mode. In Mute 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 “AC-Coupled click and
pop operation” on page 13.
Before power-up and power-down of the ISL54210 part,
the V_BUS and CTRL control pins should be driven to
ground or tri-stated. This will put the switch in the mute
state, which turns all switches OFF and activates the click
and pop circuitry. This will minimize transients at the
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FN6661.2
March 18, 2010