AN10881
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© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
29 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
Example:
•
I
SUPIC(between 2 bursts)
= 4 mA
•
V
SUPIC(burst)
= V
aux burst
15 V = 19 V
15 V = 4 V
•
t
between 2 bursts
= 25 ms
(4)
5.6.2 Value of the capacitor for SUPREG
The capacitor on SUPREG must not be larger than the capacitor on SUPIC to support
charging of SUPREG during an HV source start. This is to prevent a severe voltage drop
on SUPIC due to the charge of SUPREG. If SUPIC is supplied by an external (standby)
source, this is not important.
SUPREG is the supply for the current of the gate drivers. Keeping current peaks local can
be achieved using an SMD ceramic capacitor supported by an electrolytic capacitor. This
is necessary to provide sufficient capacitance to prevent voltage drop during high current
loads. The value of the capacitor on SUPREG must be much larger than the (total)
capacitance of the MOSFETs that must be driven (including the SUPHS parallel load and
capacitor bootstrap construction) to prevent significant voltage drop.
When considering the internal voltage regulator, the value of the capacitance on SUPREG
must be
1
F. Often a much larger value is used for the reasons mentioned previously.
5.6.3 Value of the capacitor for SUPHS
The SUPHS capacitor must be much larger than the gate capacitance to support charging
the gate of the high side MOSFET. This is to prevent a significant voltage drop on SUPHS
by the gate charge. When Burst mode is applied, SUPHS is discharged by 37
A during
the time between two bursts.
C
SUPIC
I
SUPIC start
-
up
between
2
bursts
t
between
2
bursts
V
SUPIC burst
-----------------------------------------
4
mA
25
ms
4
V
---------------
25
F
=
=
