The AVR DX PIM comes in two variants:
- Internal Operational Amplifier variant: Based on the AVR128DB48 microcontroller which includes an internal op amp
- External Operational Amplifier variant: Based on the AVR128DA48, it represents the plain version and uses the external MCLV-2 op amp
The usage of the internal op amps relies mainly on microcontrollers that contain the op amp module such as the AVR DB family, eliminating the need for an external op amp. The amplified current is then fed through a comparator window with software-adjustable limits leaving the user the possibility to select between internal or external references by changing a single selection jumper on the PIM.
A special configuration board is needed to gain access to both signals from the current shunts and the back-EMF of the motor. It comes in the same package as the PIM. This is only needed when using the internal op amp current reference. However, if the PIM is configured to run with an external op amp, it can also work with the provided MCLV-2 EXTERNAL OP_AMP configuration board.