ISL54057 Datasheet, PDF (7/10 Pages) Intersil Corporation – Ultra Low ON-Resistance, Low-Voltage, Single Supply, Differential 4 to 1 Analog Multiplexer

ISL54057
Test Circuits and Waveforms (Continued)
V+
C
SIGNAL
GENERATOR
A_x
COM_A
ANALYZER
0V or V+
Channel
Select
ADD1
ADD0
COM_B
R_L
GND
B_x
INH
50Ω
N.C.
IMPEDANCE
ANALYZER
V+
C
0V or V+
Ax or Bx
ADD1
ADD0
COMA or COMB
GND INH
Channel
Select
Crosstalk is measured between adjacent channels with one channel
ON and the other channel OFF.
Signal direction through switch is reversed and worst case values
are recorded.
FIGURE 5. CROSSTALK TEST CIRCUIT
FIGURE 6. CAPACITANCE TEST CIRCUIT
Detailed Description
The ISL54057 analog switch offer precise switching
capability from a single 1.6V to 3.6V supply with low
on-resistance (0.41Ω) and high speed operation
(t_ON = 27ns, t_OFF = 18ns). The devices are especially well
suited to portable battery powered equipment thanks to the
low operating supply voltage (1.6V), low power consumption
(0.17µW), low leakage currents (60nA max) , and the tiny
µTQFN package. The ultra low on-resistance and Ron
flatness provide very low insertion loss and distortion to
applications that require signal reproduction.
Supply Sequencing And Overvoltage Protection
With any CMOS device, proper power supply sequencing is
required to protect the device from excessive input currents
which might permanently damage the IC. All I/O pins contain
ESD protection diodes from the pin to V+ and to GND (see
Figure 7). To prevent forward biasing these diodes, V+ must
be applied before any input signals, and the input signal
voltages must remain between V+ and GND.
If these conditions cannot be guaranteed, then precautions
must be implemented to prohibit the current and voltage at
the logic pin and signal pins from exceeding the maximum
ratings of the switch. The following two methods can be used
to provided additional protection to limit the current in the
event that the voltage at a signal pin or logic pin goes below
ground or above the V+ rail.
Logic inputs can be protected by adding a 1kΩ resistor in
series with the logic input (see Figure 7). The resistor limits
the input current below the threshold that produces
permanent damage, and the sub-microamp input current
produces an insignificant voltage drop during normal
operation.
This method is not acceptable for the signal path inputs.
Adding a series resistor to the switch input defeats the
purpose of using a low R_ON switch. Connecting schottky
diodes to the signal pins as shown in Figure 7 will shunt the
fault current to the supply or to ground thereby protecting the
switch. These schottky diodes must be sized to handle the
expected fault current.
OPTIONAL
SCHOTTKY
DIODE
OPTIONAL
PROTECTION
RESISTOR
V+
INH
or
ADD_X
Ax or Bx
V_COMX
OPTIONAL
SCHOTTKY
DIODE
GND
FIGURE 7. OVERVOLTAGE PROTECTION
7
FN6379.0
September 29, 2006