This kind of operation, together with the extremely low IC quiescent current, allows very low input power

consumption in no-load and light load, while the low DRAIN peak current value, IDLIM_PFM, prevents any audible

noise which could arise from low switching frequency values. When the output load is increased, VCOMP

increases and PFM is exited. VCOMP reaches its maximum at VCOMPH, corresponding to the DRAIN current

limitation (IDLIM).

VIPER319HC version has a higher IDLIM_PFM that helps to achieve a better efficiency at light load conditions

compared to VIPER319H (see Figure 28 and Figure 29).

Figure 28. Light load efficiency @ 230VAC

30

40

50

60

70

80

90

0.005

0.125

0.25

0.5

1

2

3

Pout (W)

319H

319HC

Figure 29. No load input power vs input voltage

30

35

40

45

50

55

60

65

90

115

230

265

Vin(VAC)

319HC

319H

VIPER31

General description

DS13285 - Rev 6

page 18/39