Rev. C 03/22

7

PFS5173-5178/5274

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Timing Supervisor and Operating Frequency Range

The controller operates with a variable switching frequency over the

line frequency half-cycle, typically spanning a range of 22 – 145 kHz.

The controller also features a timing supervisor function which

monitors and limits the maximum switch on-time and off-time as well

and ensures minimum cycle on-time. Figure 7 shows the typical

half-line frequency profile of the device switching frequency as a

function of input voltage at maximum load.

The next figure shows for a given line condition of 115 VAC, the effect of EcoSmart™ on the switching frequency as a function of load.

Figure 7. Frequency Variation Over Line Half-Cycle as a Function of Input Voltage.

Figure 8. Frequency Variation Over Line Half-Cycle as a Function of load (V

IN = 115 VAC).