AN10881
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
27 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
Example:
•
Q
gate
= 40 nC
•
f
bridge
= 100 kHz
Remark:
The calculated value is generally higher than the practical value, because the
switching operation deviates from the MOSFET specification for Q
gate
.
5.5.5.2
GATEPFC
(2)
Example:
•
Q
gate
= 40 nC
•
f
bridge
= 100 kHz
5.5.6 SUPREG supply voltage for other circuits
The regulated voltage of SUPREG can also be used as a regulated supply for an external
circuit. The load of the external circuits affects the start-up (time) and the total load
(IC + external circuit) of SUPREG during operation.
5.5.6.1
Current available for supplying an external circuit from SUPREG
The total current available from SUPREG is a minimum of 40 mA. How much current the
IC is using must be determined to ensure how much current is available for an external
circuit.
I
SUPREG_for_external
= 40 mA
I
SUPREG_for_IC
With respect to the IC, by far the greatest amount of current from SUPREG is consumed
by the MOSFET drivers (GATELS, GATEHS and GATEPFC). Other circuit parts in the IC,
consume a maximum of 3 mA.
I
SUPREG_for_IC
= I
SUPREG_for_MOSFET-drivers
+ I
SUPREG_for_other_IC-circuits
I
SUPREG_for_IC
= I
SUPREG_for_MOSFET-drivers
+ 4 mA
max
I
SUPREG_for_MOSFET-drivers
can be estimated by the method provided in
5.5.6.2
An estimation by measurement
The current used by SUPIC, while supplying the circuit from an external power supply, can
be assumed as a first approximation of how much current the IC circuits take from
SUPREG. Using this value, an estimation can be made of the power available for external
circuits.
Remark:
The highest power consumption value is reached when the MOSFET drivers
are switching at the highest frequency.
I
SUPIC
2
40
nC
100
kHz
8
mA
=
=
I
SUPIC
Q
gate
f
PFC
=
I
SUPIC
40
nC
100
kHz
4
mA
=
=
