The ADG1438 and ADG1439 are CMOS analog matrix switches with a serially controlled 3-wire interface. The ADG1438 is an 8-channel matrix switch， and the ADG1439 is a dual 4-channel matrix switch. The ADG1438/ADG1439 use a versatile 3-wire serial interface that operates at clock rates of up to 50 MHz and is compatible with standard SPI， QSPI?， MICROWIRE?， and DSP interface standards. The output of the shift register， SDO， enables a number of the ADG1438/ADG1439 devices to be daisy-chained. On power-up， the internal shift register contains all zeros， and all switches are in the off state. Each switch conducts equally well in both directions when on， making these devices suitable for both multiplexing and demultiplexing applications. Because each switch is turned on or off by a separate bit， these devices can also be configured as a type of switch array， where any， all， or none of the eight switches can be closed at any time. The input signal range extends to the supply rails. All channels exhibit break-before-make switching action， preventing momentary shorting when switching channels. The ultralow on resistance and on-resistance flatness of these switches make them ideal solutions for data acquisition and gain switching applications where low distortion is critical. iCMOS? construction ensures ultralow power dissipation， making the parts ideally suited for portable and batterypowered instruments.