ISL54406 Datasheet, PDF (9/16 Pages) Intersil Corporation – Stereo Click and Pop Eliminator with Audio Muting

ISL54406
Application Block Diagram
3.3V
0.1µF
LEFT
SPEAKER
RIGHT
SPEAKER
VDD
SEL1
LOGIC CONTROL
L_SHUNT
SEL2
4MΩ _4MΩ
6Ω
LOUT
220µF
LIN
220kΩ
ROUT
CLICK AND POP
CIRCUITRY
220µF
RIN
220kΩ
6Ω
R_SHUNT
GND
ISL54406
µCONTROLLER
AUDIO
CODEC
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 9.
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_RMS) with V_DD >
2.7V, these switches have an extremely low r_ON
resistance 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 9.
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.
Logic Control Voltage Levels:
SEL1 and SEL2 = Logic “0” (Low) when ≤ 0.5V or
Floating.
SEL1 and SEL2 = Logic “1” (High) when ≥ 1.4V
9
FN6578.1
July 14, 2010