AN10881
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© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
18 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
5.2.3 SUPIC current consumption
The SUPIC current consumption depends on the state of the TEA1713.
•
Disabled IC state:
When the IC is disabled via the SSHBC/EN pin, the current consumption is low at
250
A.
•
SUPIC charge, SUPREG charge, thermal hold, restart and shutdown state:
During the charging of SUPIC and SUPREG before start-up, during a restart
sequence or during shutdown after activation of protection, only a small part of the IC
is active. The PFC and HBC are disabled. The current consumption from SUPIC in
these states is small at 400
A.
•
Boost charge state:
PFC is switching and HBC is still off. The current from the high-voltage start-up source
is large enough to supply SUPIC, so current consumption is below the maximum
current (5.1 mA) that SUPHV can deliver.
•
Operating supply state:
Both PFC and HBC are switching. The current consumption is larger. The MOSFET
drivers are dominant in the current consumption (see
), especially during
soft-start of the HBC, when the switching frequency is high, and also during normal
operation. Initially, the stored energy in the SUPIC capacitor delivers the SUPIC
current. After a short time the current supply is taken over by the supply source on
SUPIC during normal operation.
5.3 SUPIC supply using HBC transformer auxiliary winding
5.3.1 Start-up by SUPHV
In a standalone power supply application, the IC can be started by a high-voltage source
such as the rectified mains voltage by connecting the high-voltage input SUPHV to the
boost voltage (PFC output voltage).
The internal HV start-up source, which delivers a constant current from SUPHV to SUPIC,
charges the SUPIC and SUPREG. SUPHV is operational at a voltage > 25 V.
As long as the voltage at SUPIC is below the short circuit protection level (0.65 V), the
current from SUPHV is low (1.1 mA). This is to limit the dissipation in the HV start-up
source when SUPIC is shorted to ground.
During normal conditions, SUPIC quickly exceeds the protection level and the HV start-up
source switches to normal current (5.1 mA). The HV start-up source switches off when
SUPIC has reached the start level (22 V). The current consumption from SUPHV is low
(7
A) when switched off.
When SUPIC has reached the start level (22 V), SUPREG is charged. When SUPREG
reaches the level of 10.7 V, it enables operation of HBC and PFC.
The auxiliary winding supply of the HBC transformer must take over the supply of SUPIC
before it is discharged to the SUPIC under voltage stop level (15 V).