The MAX4539/MAX4540 low-voltage, CMOS 8-channel (MAX4539) and dual 4-channel (MAX4540) multiplexers are ideal for precision ADC calibration and system selfmonitoring applications. These calibration multiplexers (cal-muxes) have precision resistor-dividers to generate accurate voltage ratios from an input reference voltage. The reference ratios include 15/4096 and 4081/4096 of the external reference voltage, accurate to 15 bits, and 1/2V+ and 5/8(V+ - V-), accurate to 8 bits. The external reference voltage as well as ground can also be switched to the output. The MAX4539/MAX4540 have enable inputs and address latching. All digital inputs have 0.8V and 2.4V logic thresholds, ensuring both TTL- and CMOS-logic compatibility when using a 5V or a single +5V supply. Protection diodes at all inputs provide an ESD rating >2kV.