Figure 1. STNRGPF02: Inrush current limiter with resistor in series to output capacitor

VAC

S1

C

R

The switch S1 can be a silicon device as Triac or a mechanical switch of a relay.

1.1.2

Inrush current limiter function with controlled bridge (STNRGPF12 only)

The second method to control the charge current of output capacitor is to replace the input bridge rectifier with a

controlled one, The STNRGPF12 modulates progressively the conduction time of the switches S1 and S2 in order

to charge smoothly the output capacitor avoiding overcurrent’s in the systems. One implementation of this method

circuit may use Silicon Controlled Rectifier (SCR) and the circuit in figure 2 is shown. The high side of input

rectifier bridge it’s composed by SCR’s S1, S2 and the low side are diodes

Figure 2. STNRFPF12: Inrush current limiter with controlled rectifier bridge

VAC

C

S1

S2

This methodology can be applied only when an inductor is present on the line. In this case an inductor is already

present because the application is an Interleaved PFC.

STNRGPF02, STNRGPF12

Inrush current limiter function description

DS12895 - Rev 2

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