The demand for analog switches that can route audio signals from a variety of sources is being spurred by high-speed audio, video and data switching. Such activity is especially robust in portable applications like cell phones; MP3, CD/DVD and video players; digital cameras; and PDAs.
Key features of recent switches include, fast switching time, low on resistance R(ON), low power consumption, dual and bidirectional versions and tiny packages.
Vendors include Analog Devices, Austriamicrosystems, Fairchild Semiconductor, Intersil, Maxim Integrated Products, Vishay Intertechnology and Texas Instruments.
Intersil Corp.'s (Milpitas, Calif.) dual analog switch (ISL84684) touts R(ON) of less than 0.5 ohms over the full input signal range for low signal loss and minimal distortion. With signal-to-distortion of 78 dB, the ISL84684 will not compromise MP3 or FM radio performance, the company said. The 2.0 x 1.5-mm single-pole, double-throw (SPDT) switch can “mux-in” such additional functionality such as MP3 playback and FM radio.
Austriamicrosystems (Raleigh, N.C.) claims its first family of high-performance analog switches offer a 40 percent switching time improvement over competing devices, while maintaining low R(ON) flatness and channel matching. The switches combine 0.03 microwatt power consumption typical and fast switching (up to 250 milliamps). The AS1741 provides R(ON) of 0.8 ohm (3-voltt supply) and 2.5 ohm (1.8-V supply).
Texas Instruments Inc. (Dallas) says low total harmonic distortion (THD) and low crosstalk suit this TS5A3159 SPDT analog switch for mobile applications. Designed to operate from 1.65 to 5.5-V, the switch features 0.01 percent THD and -65-dB crosstalk. Its 0.15-ohm R(ON) flatness allows low THD under rail-to-rail signal conditions making it suitable either for selecting among sources upstream of the audio power amp, or for routing downstream between an internal speaker or an external headset, TI said.
The MAX4901, MAX4902, MAX4903, MAX4904 and MAX4905 clickless dual, single-pole, single throw (SPST) and single, SPDT analog switches from Maxim Integrated Products Inc.'s (Sunnyvale, Calif.) feature integrated shunt switches to ground to reduce audio popping and clicking.
The switches' 0.6-ohm R(ON), 0.25-ohm R(ON) flatness, and 0.04 percent THD yield high audio signal quality, according to Maxim. The devices are housed in either a small 9-bump UCSP (1.5 x 1.5 mm) and an 8-pin TDFN package (3 x 3 mm).
Vishay Intertechnology Inc. (Malvern, Pa.) says its DG2799 double-pole, double-throw (DPDT) analog switch guarantees 1.6-V logic at a 4.3-V power supply. R(ON) is 0.25-ohm typical at 2.7 V; switching times of 57 nanoseconds (on) and 45 ns (off). It comes in a QFN-16 (3 x 3-mm) package.
Vishay's DG2714, meanwhile, is a break-before-make SPDT monolithic CMOS analog switch. The DG2715 and DG2716 are bidirectional SPST switches. Vishay also offers the DG2741, DG2742, and DG2743 single-supply, dual SPST switches with R(ON) values down to 0.4 ohm typical at 2.7 V.
Fairchild Semiconductor Corp. (South Portland, Maine) is calling its FSUSB23 the smallest single-port USB 2.0 high-speed analog switch in a MicroPak chip-scale package (CSP). The FSUSB23 consumes less than 1 microamp of power and offers wide bandwidth operation at more than 720 MHz. At 3.36-mm squared, the FSUSB23's 1.6 x 2.1 mm MicroPak 10-terminal CSP is said to offer a 68 percent footprint reduction compared with some competitive switches.
Analog Devices, Inc. (Norwood, Mass.) says its low-voltage CMOS ADG787 contains two independently selectable SPDT switches and can also be used for routing USB 1.1 signals. Operating from a 4.2-V to 5.5-V input, the part is said to offer R(ON) of 2.5 ohms typical, with a maximum of 3.35 ohms at 85°C.