L4984D STMicroelectronics, L4984D Datasheet - Page 19

• Manufacturer Part Number: L4984D
• Description: Power Factor Correction ICs Current Mode PFC CCM Line Modulated Bi
• Manufacturer: STMicroelectronics

Specifications of L4984D

• Rohs: yes

L4984
compliance with conducted EMI emission regulations. The relative frequency change due to
the output voltage ripple is:
Equation 12
Figure 28. Line-modulated fixed-off-time-controlled boost PFC: current waveforms
As a result of the operation of the circuit in
regulator draws from the power line is not exactly sinusoidal but is affected by distortion that
is lower as the current ripple in the boost inductor is smaller as compared to its peak value.
Figure 28
at different input voltages.
In the diagram on the left-hand side the line (input) current waveform is shown for different
line voltages, while on the right-hand side the envelope of the inductor current at minimum
and maximum line voltage is shown.
The input current waveform relevant to Vin = 88 V
operation of the boost inductor is CCM throughout the entire line cycle as testified by the
inductor current envelope. The brown waveform is relevant to Vin = 190 V
condition where CCM operation no longer occurs at zero-crossings (this voltage value, for a
given power level, depends on the inductance value of the boost inductor); a certain degree
of distortion is already visible.
Vin = 88 Vac
Vin = 264 Vac
shows some theoretical waveforms, relevant to full load condition, in a line cycle
Line voltage phase angle (rad)
Vin = 230 Vac
Vin = 190 Vac
Doc ID 023489 Rev 3
Line current
Δ
f
sw
f
sw
=
Figure 26
1
+
Δ
Vout
Vout
Δ
Vout
Vout
ac
shows no visible sign of distortion; the
, the current that the boost PFC pre-
Vin = 264 Vac
Line voltage phase angle (rad)
Application information
Vin = 88 Vac
ac
, which is the
current envelope
Boost inductor
AM13244v1
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