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AN10881
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© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
22 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
5.4 SUPIC supply by external voltage
5.4.1 Start-up
When the TEA1713 is supplied by an external DC supply, the SUPHV pin can remain
unconnected. The SUPIC start level is now 17 V.
When the SUPIC exceeds 17 V the internal regulator is activated and charge SUPREG.
At SUPREG
10.7 V, GATELS is switched on for the bootstrap function to charge
SUPHS. And at the same time the PFC operation is internally enabled. When all enable
conditions are met, the TEA1713 starts the PFC function and when V
boost
reaches
approximately 90 % (SNSBOOST
2.3 V) of its nominal value, the HBC starts.
5.4.2 Stop
Operation of the TEA1713 can be stopped by switching off the external source for SUPIC.
When the voltage level on SUPIC drops below 15 V, operation is stopped.
In case of shutdown (because of protection), this state is reset by internal logic when the
SUPIC voltage drops below 7 V.
5.5 SUPREG
SUPIC has a wide voltage range for easy application. Because of this, SUPIC cannot be
directly used to supply the internal MOSFET drivers as this would exceed the allowed
gate voltage of many external MOSFETs.
The TEA1713 contains an integrated series stabilizer to avoid this issue and to create a
few other benefits. The series stabilizer generates an accurate regulated voltage on
SUPREG on the external buffer capacitor.
This stabilized SUPREG voltage is used for:
•
Supply of internal PFC driver
•
Supply of internal low-side HBC driver
•
Supply of internal high-side driver via external components
•
Reference voltage for optional external circuits
The series stabilizer for SUPREG is enabled after SUPIC has been charged. In this way
optional external circuitry at SUPREG does not consume from the start-up current during
the charging of SUPIC. The capacitor on SUPIC acts as a buffer at charge of SUPREG
and start-up of the IC.
The SUPREG voltage must reach the V
start(SUPREG)
level before the IC starts operating to
ensure that the external MOSFETs receive sufficient gate drive, provided that the SUPIC
voltage has also reached the start level.