1.4.2 Internal Resistor Ladder Does Not Disconnect in Unity Gain Mode

When using the OPA module in a unity gain configuration, the internal resistor ladder will not automatically disconnect from the operational amplifier, which may adversely affect the gain of the circuit. This applies when the peripheral has been configured to operate in Unity Gain mode in software by setting the UG bit, or in hardware using the hardware controlled override feature.

Work around

Disconnect the internal resistor ladder from the operational amplifier by writing to the Inverting Input Channel Selection (NCH) bits. All signals can be disconnected from the operational amplifier by writing 0b000 to the NCH bits.

Affected Silicon Revisions

A4A5A6B1
X