ISL54207 Datasheet, PDF (10/14 Pages) Intersil Corporation – Low Voltage, Dual SPDT, USB/CVBS/ Audio Switches, with Negative Signal Capability

ISL54207
USB Mode
If the VBUS pin = Logic “1” and CTRL pin = Logic “0” or
Logic “1,” the part will go into USB mode. In USB mode, the
NO1 and NO2 5Ω switches are ON and the NC1 and NC2
3Ω audio switches are OFF (high impedance). When a USB
cable from a computer or USB hub is connected at the
common connector, the voltage at the VBUS pin will be
driven to be in the range of 4.4V to 5.25V. The ISL54207 part
will go into the USB mode. In USB mode, the computer or
USB hub transceiver and the media player USB transceiver
are connected and digital data will be able to be transmitted
back and forth.
When the USB cable is disconnected, the ISL54207
automatically turns the NO1 and NO2 switches OFF.
Low Power Mode
If the VBUS pin = Logic “0” and CTRL pin = Logic “0,” the
part will be in the Low Power mode. In the Low Power mode,
the NCx switches and the NOx switches are OFF (high
impedance). In this state, the device draws typically 1nA of
current.
EXTERNAL V_BUS SERIES RESISTOR
The ISL54207 contains a clamp circuit between VBUS and
VDD. Whenever the V_BUS voltage is greater than the V_DD
voltage by more than 2.55V, current will flow through this
clamp circuitry into the V_DD power supply bus.
During normal USB operation, V_DD is in the range of 2.7V to
3.6V and V_BUS is in the range of 4.4V to 5.25V. The clamp
circuit is not active and no current will flow through the clamp
into the V_DD supply.
In a USB application, the situation can exist where the V_BUS
voltage from the computer could be applied at the VBUS pin
before the V_DD voltage is up to its normal operating voltage
range and current will flow through the clamp into the V_DD
power supply bus. This current could be quite high when
V_DD is OFF or at 0V and could potentially damage other
components connected in the circuit. In the application
circuit, a 22kΩ resistor has been put in series with the VBUS
pin to limit the current to a safe level during this situation.
It is recommended that a current limiting resistor in the range
of 10kΩ to 50kΩ be connected in series with the VBUS pin. It
will have minimal impact on the logic level at the VBUS pin
during normal USB operation and protect the circuit during
the time V_BUS is present before V_DD is up to its normal
operating voltage.
Note: No external resistor is required in applications where
V_BUS will not exceed V_DD by more than 2.55V.
POWER
The power supply connected at VDD (pin 1) provides power
to the ISL54207 part. Its voltage should be kept in the range
of 2.7V to 3.6V when used in a USB/Audio/Video application
to ensure you get proper switching when the V_BUS voltage is
at its lower limit of 4.4V.
Typical Performance Curves T_A = +25°C, Unless Otherwise Specified
0.11
0.4
R_LOAD = 32Ω
0.1 ^{VLOAD = 0.707VRMS}
R_LOAD = 32Ω
V_DD = 3V
0.3
0.09
V_DD = 2.6V
0.08
0.2
0.07
V_DD = 2.7V
0.06
0.05
0.1
V_DD = 3.6V
V_DD = 3V
3V_P-P
2.5V_P-P
2V_P-P
0.04
20
200
2k
20k
FREQUENCY (Hz)
FIGURE 10. THD+N vs SUPPLY VOLTAGE vs FREQUENCY
1V_P-P
0
20
200
2k
20k
FREQUENCY (Hz)
FIGURE 11. THD+N vs SIGNAL LEVELS vs FREQUENCY
10
FN6403.0
December 5, 2006