ISL54224 Datasheet, PDF (11/18 Pages) Intersil Corporation – High-Speed USB 2.0 (480Mbps) Multiplexer with Overvoltage Protection (OVP) and Overvoltage Indicator Output

ISL54224
For lowest power consumption you should use the lowest
V_DD supply.
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.
In a typical application, V_DD will be in the range of
2.8V to 4.3V and will be connected to the battery or
LDO of the portable media device.
LOGIC CONTROL
The state of the ISL54224 device is determined by the
voltage at the SEL pin and the OE/ALM pin. SEL is only
active when the OE/ALM pin is logic “1” (High). Refer to
“Truth Table” on page 2.
The ISL54224 logic pins are designed to minimize
current consumption when the logic control voltage is
lower than the V_DD supply voltage. With V_DD = 3.6V and
logic pins at 1.4V the part typically draws only 25µA.
With V_DD = 4.3V and logic pins at 2.6V the part typically
draws only 35µA. Driving the logic pins to the V_DD supply
rail minimizes power consumption.
The SEL pin and OE/ALM pin have special circuitry that
allows them to be driven with a voltage higher than the
V_DD supply voltage. These pins can be driven up to
5.25V with a V_DD supply in the range of 2.7V to 5.25V.
The SEL pin and OE/ALM pin are internally pulled low
through 4MΩ resistors to ground and can be tri-stated by
a µProcessor.
The OE/ALM pin is an open drain connection. It should be
pulled high through an external 100kΩ pull-up resistor.
The OE/ALM pin can then be driven “Low” by a
µProcessor to open all switches or it can be monitored by
the µProcessor for a “Low” when the part goes into an
over-voltage condition.
Logic Control Voltage Levels
TABLE 2. LOGIC CONTROL VOLTAGE LEVELS
V_DD
SUPPLY
RANGE
LOGIC = “0” (LOW) LOGIC = “1” (HIGH)
OE/ALM
SEL
OE/ALM
SEL
2.7V to 3.6V ≤ 0.5V
≤ 0.5V
or floating or floating
3.7V to 4.2V ≤ 0.7V
≤ 0.7V
or floating or floating
4.3V to 5.25V ≤ 0.8V
≤ 0.8V
or floating or floating
≥1.4V
≥1.7V
≥2.0V
≥1.4V
≥1.7V
≥2.0V
HSD1 USB Channel
If the SEL pin = Logic “0” and the OE/ALM pin = Logic
“1”, high-speed Channel 1 will be ON. The HSD1- and
HSD1+ switches are ON and the HSD2- and HSD2+
switches are OFF (high impedance).
When a computer or USB hub is plugged into the
common USB connector and Channel 1 is active, a link
will be established between the USB 1 transceiver section
of the media player and the computer. The device will be
able to transmit and receive data from the computer.
HSD2 USB Channel
If the SEL pin = Logic “1” and the OE/ALM pin = Logic
“1”, high-speed Channel 2 will be ON. The HSD2- and
HSD2+ switches are ON and the HSD1- and HSD1+
switches are OFF (high impedance).
When a USB cable from a computer or USB hub is
connected at the common USB connector and Channel 2
is active, a link will be established between the USB 2
driver section of the media player and the computer. The
device will be able to transmit and receive data from the
computer.
All Switches OFF Mode
If the SEL pin = Logic “0” or Logic “1” and the OE/ALM
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 ISL54224 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.
Whenever the ISL54224 senses a fault condition on the
COM pins, the OE/ALM pin will be internal pulled low by
the device and all switches will be turned OFF.
USB 2.0 V_BUS Short Requirements
The USB specification in section 7.1.1 states a USB
device must be able to withstand a V_BUS short (4.4V to
5.25V) or a -1V short to the D+ or D- signal lines when
the device is either powered off or powered on for at
least 24 hours.
The ISL54224 part has special power-off protection and
OVP detection circuitry to meet these short circuit
requirements. This circuitry allows the ISL54224 to
provide protection to the USB down-stream transceivers
connected at its signal pins (HS1D-, HS1D+, HS2D-,
HS2D+) to meet the USB specification short circuit
requirements.
The power-off protection and OVP circuitry allows the
COM pins (D-, D+) to be driven up to 5.25V or down to
-5V while the V_DD supply voltage is in the range of 0V to
5.25V. In these overvoltage conditions with a 500Ω
external VDD resistor the part draws < 55µA of current
into the COM pins and causes no stress/damage to the
IC. In addition, all switches are OFF and the shorted
V_BUS voltage will be isolated from getting through to the
other side of the switch channels, thereby protecting the
USB transceivers.
11
FN6969.0
June 7, 2010