isl54406 Intersil Corporation, isl54406 Datasheet - Page 7

• Manufacturer Part Number: isl54406
• Description: Stereo Click And Pop Eliminator With Audio Muting
• Manufacturer: Intersil Corporation

Application Block Diagram
Detailed Description
The ISL54406 device is a dual single pole-single throw
(SPST) analog switch that operates from a single DC power
supply in the range of +2.7V to +5V. It was designed to
function as a transient suppressor to eliminate Click and Pop
noise on headphones. It comes in a 10 Ld (3mmx3mm)
TDFN or a tiny 10 Ld (1.8mmx1.4mm) µTQFN package for
use in MP3 players, PDAs, cellphones, and other personal
media players.
The part consist of a pair of 2.5Ω audio switches. The audio
switches can accept signals that swing below ground by as
much as -1.5V. They were designed to pass audio left and
right stereo signals that are ground referenced with minimal
distortion.
The ISL54406 was specifically designed for MP3 players,
personal media players and cellphone applications that
require but do not have Click and Pop elimination. See
“Application Block Diagram” on page 7.
The ISL54406 contains logic control pins SEL1 and SEL2
that will determine the state of the switch. See the “Truth
Table” on page 2 for a description of each state. A detailed
description of the audio switches are provided in the section
that follows.
Audio Switches
The two 2.5Ω audio switches (L, R) are designed to pass
signals that swing 1.5V above and below ground. Crosstalk
between the audio switches is -90dB over the audio band.
These switches have excellent off-isolation of 110dB over
the audio bandwidth with a 32Ω load.
Over a signal range of ±1V (0.707V
these switches have an extremely low r
SPEAKER
SPEAKER
RIGHT
LEFT
7
RMS
ON
) with V
resistance
ROUT
LOUT
DD
220kΩ
220kΩ
> 2.7V,
GND
LOGIC CONTROL
L
SHUNT
3.3V
ISL54406
6Ω
6Ω
VDD
R
SHUNT
0.1µF
CLICK AND POP
CIRCUITRY
variation (0.03Ω). They can pass ground referenced audio
signals with very low distortion (<0.04% THD+N) when
delivering 4mW into a 32Ω headphone speaker load. See
Figures 10, 11, 12 and 13 for THD+N performance curves.
The audio drivers should be connected at the LIN and RIN
side of the switch and the speaker loads should be
connected at the LOUT and ROUT side of the switch for
proper Click and Pop elimination. The switches have Click
and Pop circuitry on the LIN and RIN side that is activated
when the SEL1 pin is driven High and SEL2 pin is driven
Low. The audio switches are turned OFF in this state. The
ISL54406 should be put in this mode before powering down
or powering up of the audio source drivers. The high
off-isolation of the audio switches along with the Click and
Pop circuitry will prevent the transients generated during
power-up and power-down of the audio source from getting
through to the headphones, thus eliminating Click and Pop
noise in the headphones. The audio switches are turned ON
and the Click and Pop circuitry disabled whenever SEL1 and
SEL2 is driven High.
ISL54406 Operation
The discussion that follows will describe using the ISL54406
in the “Application Block Diagram” on page 7.
LOGIC CONTROL
The state of the ISL54406 device is determined by the logic
level at the SEL1 and SEL2 pins. The part has four states or
modes of operation. The Audio Playback Mode, Audio Mute
Mode, Click and Pop Mode, and Shutdown Mode. Refer to
“Truth Table” on page 2 for the logic state of each mode of
operation. The SEL1 and SEL2 pins are internally pulled low
through 4MΩ resistors to ground and can be left floating to
pull the logic pins Low.
4MΩ
ISL54406
4MΩ
SEL2
SEL1
RIN
LIN
220µF
220µF
µCONTROLLER
CODEC
AUDIO
May 28, 2008
FN6578.0