Digital Potentiometer Questions - MCP41010, MCP454x/6x, MCP464x/6x - Make Before Break, Audio Applications

Does the MCP41010 feature 'make before break' when changing the wiper position?

No. Most digital potentiometers do NOT implement either a make before break or break before make functionality.

Both implementations have issues. For example, in a make before break implementation, if the wiper code goes from Zero-Scale to Full-Scale, then the RAB value is temporarily shorted by both wiper resistors being turned on (make) and the IAB would spike (VAB / (2 * RW) vs. VAB / RAB). This type of implementation is only recommended where code change range is limited, e.g., for devices that have an increment or decrement interface. Our increment/decrement devices do not implement make before break.

Does Microchip have app notes regarding digital potentiometers in audio applications?

No, but, due to continuous improvements implemented in our datasheets, the MCP454x/6x - MCP464x/6x Datasheet has information that are useful in audio applications.

In section 4.2.1, Figure 4 lists the gain as: Vout = -Vin * (Rb/Ra) + Vref * (1 + Rb/Ra). I am confused by the second term on the right of the equals sign. Traditional inverting op-amps show the gain as -Vin * (Rb/Ra). Is the equation in Figure 4-4 valid?

The equation in Figure 4-4 is correct. This section Vref * (1 + Rb/Ra) is a result of the positive input being tied to Vref rather than GND.

For additional information, please read application notes AN1316 and AN1080.

© 2018 Microchip Technology, Inc.
Notice: ARM and Cortex are the registered trademarks of ARM Limited in the EU and other countries.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.