ISL54200_07 Datasheet, PDF (8/16 Pages) Intersil Corporation – USB 2.0 High/Full Speed Multiplexer

Application Block Diagram
3.3V
ISL54200
VBUS
D-
D+
GND
V_DD
ISL54200
IN
LOGIC CIRCUITRY
COMD1
EN
4MΩ
HSD1
HSD2
COMD2
GND
FSD1
FSD2
µCONTROLLER
USB
HIGH-SPEED
TRANSCEIVER
USB
FULL-SPEED
TRANSCEIVER
PORTABLE MEDIA DEVICE
Detailed Description
The ISL54200 device is a dual single pole/double throw
(SPDT) analog switch that operates from a single DC power
supply in the range of 2.7V to 5.5V. It was designed to
function as a dual 2-to-1 multiplexer to select between a
USB high-speed transceiver and a USB full-speed
transceiver in portable battery powered products. It is offered
in a TDFN package and a small µTQFN package 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 two 7Ω full speed (FSx) switches and
two 4.5Ω high speed (HSx) switches. The FSx switches can
swing from 0V to V_DD. They were designed to pass USB
full speed (12Mbps) differential data signals with minimal
distortion. The HSx switches have high bandwidth and low
capacitance to pass USB high-speed (480Mbps) differential
data signals with minimal edge and phase distortion.
The ISL54200 was designed for MP3 players, cameras,
cellphones, and other personal media player applications
that have both high-speed and full-speed transceivers and
need to multiplex between these USB sources to a single
USB host (computer). A typical application block diagram of
this functionality is shown on page 8.
A detailed description of the two types of switches are
provided in the following sections.
FSx Switches (FSD1, FSD2)
The two FSx switches (FSD1, FSD2) are bidirectional
switches that can pass rail-to-rail signals. When powered
with a 3.3V supply, these switches have a nominal r_ON
resistance of 7Ω over the signal range of 0V to 3.3V. They
8
were specifically designed to pass USB full-speed (12Mbps)
differential signals and meet the USB 2.0 full-speed signal
quality specifications. See Figure 8.
The FSx switches can also pass USB high speed signals
(480Mbps) but do not quite meet the USB 2.0 high speed
signal quality eye diagram compliance requirement.
The maximum signal range for the FSx switches is from
-1.5V to V_DD. The signal voltage should not be allowed to
exceed the V_DD voltage rail or go below ground by more
than -1.5V.
When operated with a 2.7V to 3.6V supply, the FSx switches
are active (turned ON) whenever the IN logic control voltage
is ≤0.5V and the EN logic voltage ≥1.4V.
HSx Switches (HSD1, HSD2)
The two HSx switches (HSD2, HSD1) are bi-directional
switches that can pass rail-to-rail signals. When powered
with a 3.3V supply, these switches have a nominal r_ON of
4.5Ω over the signal range of 0V to 400mV with a r_ON
flatness of 0.4Ω. The r_ON matching between the HSD1 and
HSD2 switches over this signal range is only 0.01Ω,
ensuring minimal impact by the switches to USB high speed
signal transitions. As the signal level increases, the r_ON
switch resistance increases. At signal level of 3.3V, the
switch resistance is nominally 20Ω.
The HSx switches were specifically designed to pass USB
2.0 high-speed (480Mbps) differential signals typically in the
range of 0V to 400mV. They have low capacitance 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 Figures 9 and 10.
FN6408.1
July 11, 2007