16-Bit Industrial DAC with ±10V and 4-20mA Outputs from Maxim

The dual-range voltage-output amplifier provides a voltage proportional to the DAC value and provides either a 0 to 10V or -10V to +10V output. The current-output amplifier, also dual-range, sources a current that is proportional to the DAC value, and can source either 0-20mA or 4-20mA of current. Both the voltage and current outputs have 25% overrange capability.

The MAX5661 was designed specifically for the industrial market, and contains many features that simplify the design of programmable logic controller (PLC) modules. The integrated voltage amplifier and voltage-to-current converter eliminate the need for additional precision resistors and for matched resistors that track well over temperature. Gain resistors are terminated outside the package, which allows for simple surge and transient protection without affecting accuracy. Load-fault detection is also integrated. If an open-circuit occurs on the current output or if a short-circuit occurs on the voltage output, the open-drain fault pin will be pulled low. The status of the fault bits is available through the SPI(TM) interface. To meet possible PLC legacy requirements, the outputs can drive 1.2microfarad capacitive loads or 1H inductive loads. Power for the current output comes from a separate supply pin, thus allowing the sourced current to be provided by either the system supplies or by a 12V to 40V (24V nominal) external supply. Finally, the 10MHz SPI interface has daisy-chain capability, which minimizes the number of optocouplers required for isolated, multiple-output modules.