Additional circuitry, shown in Figure 2-4, is needed at the output of the XTR200 for compatibility with the M-CRPS standard. Diode D1 and op amp U3 form a clamp circuit which prevents the output voltage (after diode D2) from exceeding 3.3V. If the output voltage from the XTR200 is less than the clamp voltage at the non-inverting input of U3 (3.8V in the schematic), then the output of U3 saturates at the positive supply, reverse-biasing diode D1. However, if the output of the XTR200 exceeds the clamp voltage then the output of U3 goes low and sinks current through D1 to make the voltage at both the op amp's inputs equal. If using a Zener diode for the clamping function, select a low leakage type to avoid impacting the accuracy of the monitor current.

Diode D2 prevents reverse current flow back into the current monitoring circuitry if the circuit is unpowered. The M-CRPS standard defines a strict requirement of less than 500nA of leakage current into the Imon pin at 85⁰C and 12V. For this reason, both diode D1 and D2 are low-leakage types such as the BAS716. Diode leakage roughly doubles for every 10⁰C increase in temperature. Therefore, for the circuit to have <500nA of leakage at 85⁰C, there must be <7.8nA of leakage at 25⁰C.

Transistor Q1 is PJFET which can be used to pull the Imon pin low to implement "presence" functionality. The M-CRPS standard recommends this additional circuitry on the output of the Imon pin to enable backwards compatibility with older systems. Because the leakage through Q1 directly contributes to the output leakage of the pin, a low-leakage PJFET, such as the MMBFJ177 must be used for this functionality. The off-state leakage of a typical NMOS transistor is too high to meet the standard requirements.