14 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 15
SECTION 4 |
Powering Direct / Embedded Switch
Mode Power Supplies (SMPS)
Input voltage
Inrush current
Peak inrush
current
Rated steady state
input RMS current
NOTE: Voltage
and current scales
are different
Fig 4.1: Inrush current in an SMPS
TIME
Peak Current
RMS Current
Non-linear
Input Current
Pulse
Input Sine
Wave Voltage
Crest Factor = Peak Current = 3
RMS Current
Voltage (+)
Voltage (
–)
Cur
ren
t (+)
Cur
ren
t (
–)
NOTE: Voltage
and current scales
are different
Fig. 4.2: High Crest Factor of current drawn by SMPS