ISL54230 Datasheet, PDF (9/16 Pages) Intersil Corporation – Octal Multiprotocol Switch

ISL54230
and supply voltage will be reduced. The device may
unexpectedly shut down if transient voltages trigger the
POR.
Overvoltage and Short Circuit Considerations
The ISL54230 should be protected from overvoltage
conditions. The IC contains ESD protection diodes that are
back biased from the switch terminals to ground. Negative
voltages on the switch terminals that are large enough to
forward-bias these ESD protection diodes will result in a
large current flowing from ground that may destroy these
diodes. Thus signals on the switch terminals should not
swing below ground and cannot exceed the specified
“Absolute Maximum Ratings” on page 4 for safe operation.
The ISL54230 can have signals that go above the positive
supply rail with no adverse effects up to +5.5V. The ESD
protection circuitry permits the signal from going beyond the
V_DD supply (even with V_DD = 0V) without inducing large
leakage currents on the switch pins when the supply voltage
is less than +5.5V. This feature complies with the USB 2.0
Specifications for short circuit protection in the event that the
5.25V V_BUS line shorts to the USB signal lines.
Note: When the supply voltage is above the POR threshold
but below the V_BUS voltage and a V_BUS fault conditions
occurs, the V_BUS signal will be passed to the other side of
the switch if the logic control pins are biased such that the
switch is turned ON.
USB Switches (COM2x and COM3x)
The four USB FS and HS capable switches are bi-directional
analog switches that can pass rail-to-rail signals with
minimal distortion. With a 3.0V power supply these switches
have a nominal ON-resistance of 6Ω in the 0V to 400mV
signal range. The low capacitance and high bandwidth of the
switches makes them ideal for USB applications. They are
specifically designed to pass both USB FS (12Mbps) and
USB HS (480Mbps) differential signals while meeting the
USB 2.0 signal quality eye diagrams (Figures 25 and 26).
The USB switches are designed with integrated protection
circuitry for fault conditions as defined in the USB 2.0
Specifications-Section 7.1.1. If a condition where V_BUS
(5.25V) is shorted to the D+ or D- pin this will not damage
the device, even without power to the IC.
1Ω Switches (COM1A and COM4A) And 6Ω
Switches (COM1B and COM4B)
The two 1Ω switches are bi-directional analog switches that
can pass rail-to-rail signals, making them well suited for
analog or digital signal routing. The low ON-resistance of the
switches makes them ideal for switching ON/OFF power
supply lines for applications that interface with devices that
require power (ie: SIM cards or flash memory devices). With
a ON-resistance of 1Ω the power dissipation through the
switch is minimal.
The two 6Ω switches are bi-directional analog switches that
can pass rail-to-rail signals, making them well suited for
analog or digital signal routing such as audio, UART or
Full-Speed USB.
The low ON-resistance of these switches are well suited for
passing audio signals with good THD performance, even
with low impedance loads such as 32Ω headphones
(see Figure 24 for THD performance curves).
Logic Control Pins
The ISL54230 contains six logic control pins, IN1 through
IN4 for independently controlling each DPDT switch and two
OE enable pins. The logic control pins determine the state of
the switches. Refer to the “Input Select” and “OE Control”
Truth Tables on page 3.
When the OEx control pins are logic LOW, only the switches
on COM2x and COM3x are active and the switch state
determined by IN2 and IN3 respectively. When the OEx
control pins are logic HIGH, all switches are active and the
switch state determined by the INx control pins.
When the OEx control pins are in opposing logic states
either COM1x and COM2x are active or COM3x and COM4x
are active depending on what states OE1 and OE2 are at.
The active switches are controlled by the respective INx
control pin. This feature is useful for applications that
interface the ISL54230 to Master/Slave devices or
controlling two SIM cards in Dual SIM Card cellphones. The
OEx control pins permit total deactivation of each half of the
switch blocks to disable devices connected to those
switches.
LOGIC CONTROL VOLTAGE LEVELS
OEx = Logic “0” (Low) when V_OEx ≤ 0.5V
OEx = Logic “1” (High) when V_OEx ≥ 1.4V
INx = Logic “0” (Low) when V_INx ≤ 0.5V
INx = Logic “1” (High) when V_INx ≥ 1.4V
The logic control pins are +1.8V CMOS logic compatible (0.45V
V_OLMAX and 1.35V V_OHMIN) for supply voltages from +1.8V to
+3.6V. over a supply range of 1.8V to 3.3V (see Figure 23). At
3.6V the V_IL level is 0.5V maximum. This is still below the 1.8V
CMOS guaranteed low output maximum level of 0.45V, but
noise margin is reduced. At 3.6V the V_IH level is 1.4V minimum.
While this is above the 1.8V CMOS guaranteed high output
minimum of 1.35V under most operating conditions the switch
will recognize this as a valid logic high.
The digital input stages draws a larger supply current whenever
the digital input voltage is not at one of the supply rails. Driving
the digital input signals from GND to V+ with a fast transition
time minimizes power dissipation. The ISL54230 has been
designed to minimize the supply current whenever the digital
input voltage is not driven to the supply rails (0V to V+). For
example driving the device with 1.8V logic high while
operating with a 3.6V supply the device draws only 1µA of
current.
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FN6825.0
December 26, 2008