AN10907
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Application note
Rev. 1 — 28 December 2010
13 of 82
NXP Semiconductors
AN10907
TEA1613T resonant power supply control IC
6.2 SUPIC - the low voltage IC supply
SUPIC is the main IC supply. With the exception of the SUPHV circuit, all internal circuits
are either directly or indirectly supplied from this pin.
6.2.1 SUPIC start-up
SUPIC needs to be connected to an external buffer capacitor. This buffer capacitor can be
charged in several ways:
•
Internal high-voltage (HV) start-up source
•
Auxiliary supply (e.g. from a winding on the HBC transformer)
•
External DC supply (e.g. from a standby supply)
The IC starts operating when the SUPIC and SUPREG voltages have reached the start
level. The start level value of SUPIC depends on the condition of the SUPHV pin.
SUPHV
25 V
max
This is the case in a stand-alone application where SUPIC is initially charged by the HV
start-up source. The SUPIC start level is 22 V. The large difference between start level
and stop level (15 V) is used to allow discharge of the SUPIC capacitor until the auxiliary
supply can take over the IC supply.
SUPHV not connected/used
This is the case when the TEA1613T is supplied from an external DC supply. The SUPIC
start level is now 17 V. During start-up and operation the IC is continuously supplied by
the external DC supply. For this kind of application the SUPHV pin should be left open.
6.2.2 SUPIC stop, UVP and short-circuit protection
The IC stops operating when the SUPIC voltage drops below 15 V which is the
Under-Voltage Protection (UVP) of SUPIC. While in the process of stopping, the HBC
continues until the low-side MOSFET is active before stopping the HBC operation. SUPIC
has a low level detection at 0.65 V to detect a short circuit to ground. This level also
controls the current source from the SUPHV pin.
6.2.3 SUPIC current consumption
The SUPIC current consumption depends on the state of the TEA1613T.
•
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 HBC operation is disabled. The current consumption from SUPIC in
these states is small: 400
A.
•
Operating supply state:
When the HBC is operational and switching, the current
consumption is larger. The MOSFET drivers are dominant in the current consumption,
especially during a soft-start of the HBC, when the switching frequency is high, but
also during normal operation (see
). Initially the SUPIC current is
delivered by the stored energy in the SUPIC capacitor. During normal operation, this
is eventually taken over by the supply source on SUPIC.
