Samsung PPM42S2X/XAA Service Manual page 27

5-1-3(B) THE RELATION BETWEEN POWER CONSUMPTION AND POWER CONVERSION Efficiency
The power consumption and the power conversion efficiency of SMPS affect protection against heat and
system operation much.
[ If the power conversion efficiency of 100W SMPS is 70%, is the power loss of internal circuit 30W? ]
Output power consumption Po is determined by the multiplication of DC output voltage Vo and output
current Io. Input power consumption Pi is determined by the addition of output power consumption
Po and internal power loss of SMPS Pl.
Provided that the power conversion efficiency is _,
If the power conversion efficiency of 100W SMPS is 70%, the internal power loss is about 42.8W by
Equation (1). If the power conversion efficiency of 400W SMPS for 42"SD is 82%, the internal power loss
is 87.8W by Equation (1). Table 4 shows internal power loss as a function of output power for various
power conversion efficiencies.
Internal
Loss ( W)
Samsung Electronics
200
180
160
140
120
Power
100
80
60
40
20
0
120
Table 4. Power Conversion Efficiency vs. Internal Power Loss
η =
50%
140 160 180 200
Direct Current Output Power (W)
Circuit Operation Description
η =
60%
η =
70%
η =
80%
η =
90%
220 240 260 280 300
5-5