3
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AN1369.0
February 3, 2009
connecting to the load. This allows any transients generated
by the source to be discharged through the shunt resistor
first, eliminating any audible click and pop noises. With a
typical DC blocking capacitor of 200µF and the shunt
resistance having a typical value of 140
Ω,
allowing a 250ms
dead time in for discharging a transient will eliminate the
click and pop noise.
Applications
The ISL540XX ICs are designed to be a Dual SPDT or
SPST switch for multiplexing or switching of signals that
require low insertion loss, low power consumption, and
negative voltage swing capability. Such applications include
Audio/Video equipment, battery or portable devices and
medical equipment. In addition, the Click and Pop
Elimination Circuitry makes it ideal for portable audio such
as MP3 players and cell phones.
Using The Board (
Refer to Figure 2
)
Lab Equipment
The equipment, external supplies and signal sources
needed to operate the board are listed below:
1. +1.8V to +6.5V DC Power Supply
2. Audio Signal Generator
3. Audio Signal Oscilloscope
4. Logic Control Generator and/or Pulse Generator
Initial Board Setup Procedure
1. Attach the evaluation board to the DC power supply at J1
(V
CC
) and J2 (GND). Positive terminal at J1 and negative
terminal at J2. The supply should be capable of delivering
+1.8V to +6.5V and 100µ
A
of current.
2. Connect the Audio Source Signal to the NOx or NCx BNC
inputs . The analog input voltage range can be from
V
CC
-6.5V up to V
CC
.
3. Connect the Audio Signal Oscilloscope to the COMx BNC
outputs .
4. Connect the Logic Control generator to the INx logic
inputs.
NCx Switches Active
1. Drive the INx pins to logic “LOW”.
2. The NCx switches are now connected to the COMx
terminals (ISL54059, ISL54061, ISL54062, and
ISL54064 only).
3. The NOx switches have shunt resistors on the terminals
to ground (ISL54062 and ISL54063 only).
NOx Switches Active
1. Drive the INx pins to logic “HIGH”.
2. The NOx switches are now connected to the COMx
terminals (ISL54059, ISL54060, ISL54062 and ISL54063
only).
3. The NCx switches have shunt resistors on the terminals
to ground (ISL54062 and ISL54064 only).
FIGURE 2. BASIC EVALUATION TEST SETUP BLOCK DIAGRAM
+1.8V TO +6.5V
DC POWER
SUPPLY
+
-
AUDIO SOURCE
SIGNAL
LEFT
RIGHT
LOGIC CONTROL
AUDIO SIGNAL
OSCILLOSCOPE
CHA
CHB
Application Note 1369
