ISL54200_07 Datasheet, PDF (9/16 Pages) Intersil Corporation – USB 2.0 High/Full Speed Multiplexer

ISL54200
The HSx switches can also pass USB full-speed signals
(12Mbps) with minimal distortion and meet all the USB
requirements for USB 2.0 full-speed signaling. See Figure 11.
The maximum signal range for the HSx switches is from
-1.5V to V_DD. The signal voltage should not be allow to
exceed the V_DD voltage rail or go below ground by more
than -1.5V.
The HSx switches are active (turned ON) whenever the IN
voltage is ≥1.4V and the EN logic voltage ≥1.4V when
operated with a 2.7V to 3.6V supply.
ISL54200 Operation
The discussion that follows will discuss using the ISL54200 in
the typical application shown in the“Application Block
Diagram” on page 8.
POWER
The power supply connected at the VDD (pin 1) provides the
DC bias voltage required by the ISL54200 part for proper
operation. The ISL54200 can be operated with a VDD
voltage in the range of 2.7V to 5.5V. When used in a USB
application, the VDD voltage should be kept in the range of
3.0V to 5.5V to ensure you get the proper signal levels for
good signal quality.
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.
LOGIC CONTROL
The state of the ISL54200 device is determined by the
voltage at the IN pin (pin 2) and the EN pin (pin 10). IN is
only active when the EN pin is logic “1” (High). Refer to the
“Truth Table” on page 2.
The EN pin is internally pulled low through a 4MΩ resistor to
ground. For logic “0” (Low) it can be driven low or allowed to
Float. The IN pin must be driven low or high and cannot be
left floating.
Logic control voltage levels:
EN = Logic “0” (Low) when V_EN ≤0.5V or Floating.
EN = Logic “1” (High) when V_EN ≥1.4V
IN = Logic “0” (Low) when V_IN ≤0.5V.
IN = Logic “1” (High) when V_IN ≥1.4V
Full-speed Mode
If the IN pin = Logic “0” and the EN pin = Logic “1”, the part
will be in the full-speed mode. In this mode, the FSD1 and
FSD2 switches are ON and the HSD1 and HSD2 switches
are OFF (high impedance). In a typical application, V_DD will
be in the range of 2.8V to 3.6V and will be connected to the
battery or LDO of the portable media device. When a
computer or USB hub is plugged into the common USB
connector and the part is in the full-speed mode, a link will
be established between the full-speed driver section of the
media player and the computer. The device will be able to
transmit and receive data from the computer at a data rate of
12Mbps.
High-speed Mode
If the IN pin = Logic “1” and the EN pin = Logic “1”, the part
will go into high-speed mode. In high-speed mode, the
HSD1 and HSD2 switches are ON and the FSD1 and FSD2
switches are OFF (high impedance). When a USB cable
from a computer or USB hub is connected at the common
USB connector and the part is in the high-speed mode, a link
will be established between the high-speed driver section of
the media player and the computer. The device will be able
to transmit and receive data from the computer at a data rate
of 480Mbps.
All Switches OFF Mode
If the IN pin = Logic “0” or Logic “1” and the EN pin = Logic “0”,
all of the switches will turn OFF (high impedance).
The all OFF state can be used to switch between the two
USB sections of the media player. When disconnecting from
one USB device to the other USB device, you can
momentarily put the ISL54200 switch in the “all off” state in
order to get the computer to disconnect from the one device
so it can properly connect to the other USB device when that
channel is turned ON.
9
FN6408.1
July 11, 2007