SBASAP9A March 2023 – December 2024 AMC23C15
PRODUCTION DATA
The AMC23C15 has two open-drain outputs, one for each window comparator. As illustrated in Figure 6-1, OUT1 is actively pulled low when |VIN| exceeds the threshold values defined by the voltage on the REF pin. OUT2 is actively pulled low when |VIN| exceeds the threshold values defined by the internal 60mV reference.
The open-drain outputs are diode-connected to the VDD2 supply, see the Functional Block Diagram, which means the outputs cannot be pulled more than 500mV above the VDD2 supply before significant current begins to flow into the OUTx pins. In particular, the open-drain outputs are clamped to one diode voltage above ground if VDD2 is at the GND2 level. This behavior is indicated by the gray shadings in Figure 6-5 through Figure 6-10.
On a system level, the CMTI performance of an open-drain signal line depends on the value of the pullup resistor. During a common-mode transient event with a high slew rate (high dV/dt), the open-drain signal line can be pulled low because of parasitic capacitive coupling between the high side and the low side of the printed circuit board (PCB). The effect of the parasitic coupling on the signal level is a function of the pullup strength and a lower value pullup resistor results in better CMTI performance. The AMC23C15 is characterized by a relatively weak pullup resistor value of 10kΩ to make sure that the specified CMTI performance is met in a typical application with a 4.7kΩ or lower pullup resistor.