NXP Semiconductors AN10881, Application Note, Page: 84 / 102

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Application note Rev. 2 — 26 September 2011 84 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
11.2.1 HBC only
Figure 59 shows a suggestion for the setup (temporary additions to the existing
application to force operation) and the sequence for disabling/enabling the different
functions. A moderate (current) load can be applied to the converters output to ascertain
the correct functioning.
Remark: A latching, overvoltage detection on SNSOUT (> 3.5 V), can still prevent
operation.
CFMIN, GATELS, GATEHS and HB can be monitored to continuously assess the
functioning of the converter/controller.
When the PFC function is disabled, V
BOOST
can often be applied by simply applying a DC
or AC voltage to the mains input connections.
Check the regulation by increasing the input voltage V
BOOST
for the following situations in
the sequence given:
1. Initially at V
BOOST
= 0 V: the running frequency is low with a short on-time and a long
off-time. This is due to the HB detection not working properly at low voltage and the
internal slope detection (HB) not detecting a proper (fast) slope. In this situation a
quick check of the working of the PFC can be done by lowering the external supply
voltage of 2.7 V on SNSMAINS and SNSBOOST to a value below 2.5 V. This allows
the gate-drive pulses on GATEPFC to be seen. By varying the voltage, changes are
shown in on-time. After this check, revert the voltage to 2.7 V to continue the
HBC-only start-up (see
Section 11.2.2.1 ).
2. Increasing the value of V
BOOST
at a certain input voltage the HB detection works
correctly and the frequency to drive maximum power is minimal. If the HB slope
remains slow, the output current is probably low. Increasing the output current
probably results in proper HB switching.
3. When the V
BOOST
input voltage has reached a level closer to the nominal working
voltage, the correct output voltage is reached (depending on the output load), and
regulation starts working. This results in increasing the frequency with increasing the
input voltage until the nominal working voltage of V
BOOST
is set.
4. When the basic functioning of the HBC, including SNSFB regulation, is working well,
protection can be added one by one. Proper functioning or a need for change can be
evaluated.
5. When a self-supplying application is used, the external supply voltage can be
removed when the system works well at nominal V
BOOST
voltage. The system can
now start with the internal high voltage start-up supply and an auxiliary winding can
take over the SUPIC supply.
Remark: If, during debugging or starting, a protection has been activated, switching the
SUPIC supply off and on to reset a latched protection state can be required.