MAX532BCWE: A 12-Bit MDAC with Output Amplifiers

Digital-to-Analog Converters (DACs) are known for one thing – they convert a digital signal into an analog buffered or unbuffered current or voltage. But how does a Multiplying Digital-to-Analog Converter (MDAC) work?

In this article, we talked extensively about how an MDAC works, with a particular on MAX532BCWE.

What is an MDAC and How Does It Work?

The full name is Multiplying Digital-to-Analog Converter (MDAC). It is a subset of the broader Digital-to-Analog Converter (DAC) and is primarily used to produce a current or output signal that is a product of the given code and the reference voltage.

The Difference between MDAC and DAC

You may be wondering what the difference or differences might be between the way an MDAC functions and the way a DAC functions.

Basically, the two work the same way, in terms of how they convert or model digital signal into the analog variant.

However, certain key performance metrics set them apart. An MDAC typically uses a variable or varying reference voltage – which is quite different from what the DAC offers.

If it were to be a DAC, the data converters would typically require the standard Digital-to-Analog (DAC) to work with a fixed reference voltage.

However, the MDAC tows a different path with the varying reference voltage that offers more precision and cuts down on noise dissipation.

Space-Saving Capabilities

If you are looking for an MDAC with advanced space-spacing capabilities, it has got to be MAX532BCWE. The space-saving capabilities include the following:

The Package Makes all the Difference

The major space-saving capability of the MAX532BCWE is the type of package it uses. It is the 16-pin DIP with a wide SO package.

MAX532BCWE also saves space with the 3-wire serial interface. This interface goes a long way to minimize or cut down on the number of package pins used with the MAX532BCWE MDAC.

In addition to reducing the number of pins used, the interface also uses less circuit board space than the parallel-interface parts do.

Maximum Operation

Maximum operation is assured with MAX532BCWE, via the supported power supplies of ±12V to ±15V.

Cross-Interface Compatibility

MAX532BCWE’s 3-wire interface also makes it compatible with other interfaces, such as the MicrowireTM, SPITM and the QSPITM.

Besides the interface compatibility, MAX532BCWE is also compatible with the following:

  • CMOS
  • TTL

No External Component Needed

MAX532BCWE doesn’t necessarily need an external user trim to function optimally.

Typical Applications

MAX532BCWE’s serial interface is one major factor for the multi-application support. It simplifies both the transformer-isolated and the opto-coupler-isolated applications.

The following are some of the supported applications:

  • Servo controls
  • Automatic test equipment
  • Motion control systems
  • Arbitrary Waveform generators
  • Programmable-gain amplifiers

Data Read-Back

It is now possible to read-back the data on the MAX532BCWE and that is because of the function of the serial output. The serial input called DOUT allows for the cascading of multiple MAX532 MDACs. The result is the read-back of the data written to the device.

The Relevance of MDAC in Today’s Signal Conversion

Multiplying Digital-to-Analog Converter (MDAC), like the standard DAC, has several roles to play in signal conversion.

The most significant thereof is the faster connection to other interfaces via the 6MHz 3-wire interface.

The other reasons why choosing an MDAC is worth the investment are:

1. MAX532BCWE Uses a Single Power Supply

When power supply is overly used, there is a likelihood that it would negatively impact the board’s performance. As much as power supply is essential, it also makes sense to keep it at the barest performance levels.

Most MDACs aren’t power-centric, in the sense that they don’t necessarily use much power. For example, these MDACs use a single supply to power the circuit – a model that cuts down on the need for dual power supplies.

It is worthy of note that the power supply, although single, takes a lot of process. First, the output current has to be converted into a voltage, using the on-amp in a transimpedance configuration at the MDAC’s current output terminal.

Next, the output voltage would be created via the transimpedance stage. To stabilize the creation, an opposite polarity to that of the VREF has to be created.

2. No Need for a Negative Rail

Most MDACs don’t have any need for a negative rail. Rather, they tend to use the device (MDAC) in “reverse.” Doing this allows for the formation of a binary weighted voltage divider.

Your Guide to Choosing an MDAC

If you are to choose a Multiplying Digital-to-Analog Converter (MDAC) today, what would you most likely look out for?

Here are the major things we would like you to pay attention to when choosing the device:

Choose the One with a Good Amplifier

The amplifier helps the MDAC to work and you don’t want to make a wrong choice. When choosing an amplifier, you want to put the following into perspective:

Load Buffering

One amplifier is suitable for buffering the voltage output of the MDAC from the load. However, there might be a need for another.

If that were to be the case, the second amplifier should be used for buffering the reference voltage input to the Digital-to-Analog (DAC) ladder.

It may also be worthwhile to use a third amplifier called the “operational amplifier.” How does it work? The operational amplifier works by maintaining the output settling time and the instantaneous current.

The combination of those two helps to cut down on the impact that the load transient might have on the settling time.

RON Mismatching Considerations

While the load buffering, the choice of an amplifier and the choice of an MDAC are all important; it is also imperative to consider the RON.

The goal is to use a voltage that matches the RON requirements, as that would go a long way to prevent RON mismatching. Also, the mismatching shouldn’t exceed or be above the absolute maximum rating for the device/MADC.

Product Attributes

Here is a tabular representation of MAX532BCWE’s properties:

AttributesDescriptions
Type of OutputVoltage – Buffered
Number of Bits12
Voltage – Supply, Analog±11.4V ~ 16.5V
Settling Time2.5µs
Supported Data InterfaceSerial Peripheral Interface (SPI)
Type of ReferenceExternal
Operating TemperatureBetween 0˚C and 70˚C
Number of D/A Converters2
ArchitectureR-2R

Final Words on MAX532BCWE

MAX532BCWE’s complete, dual, serial-input MADC with a 12-bit design allows for real-time cascading and full-performance of the target devices/applications.