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RPLLNR3

Figure 8: Ignition ramp (crossed lamps)

During the Ignition Ramp mode the voltage on the CPH pin of the IR2167 continues to ramp up until

the voltage at the CPH pin of the IR2167 exceeds the Run mode threshold (5.1V). Over-current

sensing is also enabled at the beginning of the Ignition Ramp mode. A full explanation of the function-

ality of the over-current sensing is in the section on Fault Mode.

Run Mode

At the end of the Ignition Ramp mode (CPH pin > 5.1V) the ballast switches to the Run mode at which

point the frequency is shifted to the run frequency. The run frequency is determined by the parallel

combination of resistors RT and RRUN and capacitor CT. Resistor RRUN is connected in parallel by

turning on the internal open drain MOSFET connected to the RUN pin of the IR2167 (see IR2167

block diagram). The sensing of under-current conditions and the 1-3V window comparator in the SD

pin are also enabled at the beginning of the Run mode. The full explanation of the functionality of the

under-current sensing and end-of-life sensing is in the section on Fault Mode. Figure 9 shows the

functionality of the CPH, RPH and RUN pins of the IR2167 during Startup, Preheat, Ignition Ramp

and Run modes.