7.3.2 Current Monitor

In current output mode (M2 = high), the XTR305 provides high output impedance. A precision current mirror generates an exact 1/10th copy of the output current and this current is either routed to the summing junction of the OPA to close the feedback loop (in the current output mode) or to the I_MON pin for output current monitoring in other operating modes.

The high accuracy and stability of this current split results from a cycling chopper technique. This design eliminates the need for a precise shunt resistor or a precise shunt voltage measurement, which would require high common-mode rejection performance.

During a saturation condition of the DRV output (the error flag is active), the monitor output (I_MON) shows a current peak because the loop opens. Glitches from the current mirror chopper appear during this time in the monitor signal. This part of the signal cannot be used for measurement.