FA5527 FUJI [Fuji Electric], FA5527 Datasheet - Page 31

• Manufacturer Part Number: FA5527
• Description: Fuji Switching Power Control IC
• Manufacturer: FUJI [Fuji Electric]

(12) Loss calculation
Since it is hard to directly measure IC loss, an example of
calculating approximate IC loss is given below.
Pd = Vcc * ( Iccop1 + Qg * f ) + V
consumption current of the IC, Qg is total gate charge of
the MOSFET, f is switching frequency, V
voltage and IHrun is a current flowing into the VH pin when
the IC operates.
is a little greater than the actual loss. Take into
consideration variation and temperature characteristics of
each value
(Example)
waveform at power supply of 264Vac, the average VH pin
voltage is approximately 119V.
Qg = 80nC at Tj = 25 degree.
specifications IHrun = 25uA = 0.025mA ( typ. ), Iccop1 =
1.4mA ( typ. ) and f = 60kHz = 0.06MHz ( typ.).
Pd = 18V * ( 1.4mA + 80nC * 0.06MHz ) + 119V * 0.025mA
AN-087E Rev.1.0
April-2011
IC loss shall be determined to use the IC within its rating.
Total IC loss, Pd, is obtained by the following equation:
Where Vcc is the supply voltage to the IC, Iccop1 is
This equation gives an approximate value of Pd, which
When the VH pin is connected to half-wave rectification
Under above condition, let us suppose Vcc = 18V and
When using FA5528 or FA5538, according to the
Thus, typical IC loss Pd:
= 115mW ( typ. )
Fuji Electric Co., Ltd.
VH
* IHrun
FA5526/5527/5528/5536/5537/5538
VH
is VH pin
31
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