ISL54222IRUZ-T INTERSIL [Intersil Corporation], ISL54222IRUZ-T Datasheet - Page 7

• Manufacturer Part Number: ISL54222IRUZ-T
• Description: High-Speed USB 2.0 (480Mbps) Multiplexer
• Manufacturer: INTERSIL [Intersil Corporation]

Application Block Diagram
Detailed Description
The ISL54222 device is a dual single pole/double throw
(SPDT) analog switch configured as a DPDT that operates
from a single DC power supply in the range of 1.8V to 3.3V.
It was designed to function as a dual 2-to-1 multiplexer to
select between two USB high-speed differential data signals
in portable battery powered products. It is offered in a TDFN,
MSOP, and a small µTQFN packages for use in MP3
players, cameras, PDAs, cellphones, and other personal
media players. The device has an enable pin to open all
switches.
The part consists of four 5.5Ω high speed (HSx) switches.
These switches have high bandwidth and low capacitance to
pass USB high-speed (480Mbps) differential data signals
with minimal edge and phase distortion. They can also swing
from 0V to V
data signals with minimal distortion.
The ISL54222 was designed for MP3 players, cameras,
cellphones, and other personal media player applications
that have multiple high-speed or full-speed transceivers
sections and need to multiplex between these USB sources
to a single USB host (computer). A typical application block
diagram of this functionality is previously shown.
A detailed description of the HS switches is provided in the
following section.
High-Speed (HSx) Switches
The HSx switches (HSD1-, HSD1+, HSD2-, HSD2+) are
bi-directional switches that can pass rail-to-rail signals.
When powered with a 1.8V supply, these switches have a
nominal r
with a r
HSD1 and HSD2 switches over this signal range is only
0.072Ω, ensuring minimal impact by the switches to USB
ON
ON
flatness of 0.44Ω. The r
DD
of 5.5Ω over the signal range of 0V to 400mV
to pass USB full speed (12Mbps) differential
VBUS
D-
D+
GND
7
ON
matching between the
D-
D+
SEL
LOGIC CIRCUITRY
ISL54222
V
GND
DD
ISL54222
HSD1+
HSD2+
HSD1-
HSD2-
OE
high speed signal transitions. As the signal level increases,
the r
the switch resistance is nominally 12Ω. See Figures 7, 8, 9,
10, 11, 12 in the “Typical Performance Curves” beginning on
page 9.
The HSx switches were specifically designed to pass USB
2.0 high-speed (480Mbps) differential signals in the range of
0V to 400mV. They have low capacitance (6.5pF) and high
bandwidth to pass the USB high-speed signals with
minimum edge and phase distortion to meet USB 2.0 high
speed signal quality specifications. See Figure 13 in the
“Typical Performance Curves” on page 10 for USB
High-speed Eye Pattern taken with switches in the
differential signal paths.
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 14
and 15 in the “Typical Performance Curves” on page 11 for
USB Full-speed Eye Pattern taken with switches in the
differential signal paths.
The maximum normal operating signal range for the HSx
switches is from 0V to V
allow to exceed the V
more than -0.3V for normal operation.
However, in the event that the USB 5.25V V
shorted to one or both of the D-/D+ pins, the ISL54222 has
special fault protection circuitry to prevent damage to the
ISL54222 part. The fault circuitry allows the signal pins (D-,
D+, HSD1-, HSD1+, HSD2-, HSD2+) to be driven up to 5.5V
while the V
this condition the part draws < 300µA of I
causes no stress to the IC. In addition when V
(ground) all switches are OFF and the fault voltage is
isolated from the other side of the switch. When V
ON
switch resistance increases. At signal level of 1.8V,
DD
supply voltage is in the range of 0V to 3.3V. In
DD
PORTABLE MEDIA DEVICE
DD
voltage rail or go below ground by
µCONTROLLER
TRANSCEIVER
TRANSCEIVER
HIGH_SPEED
FULL-SPEED
FULL-SPEED
HIGH-SPEED
. The signal voltage should not be
USB
USB
OR
OR
#2
#1
DD
BUS
current and
DD
voltage gets
February 9, 2009
DD
is at 0V
is in the
FN6835.0