TEA18361LT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 2 — 12 December 2013 5 of 29
NXP Semiconductors
TEA18361LT
GreenChip SMPS control IC
7. Functional description
7.1 General control
Figure 3 shows a typical configuration of the TEA18361LT, including flyback circuit
controller.
7.1.1 Start-up and UnderVoltage LockOut (UVLO)
Initially, the capacitor on the VCC pin is charged from the high-voltage mains using the
HV pin. As long as V
CC
is below V
startup
, the IC current consumption is minimized to
40 A.
When V
CC
reaches the V
startup
level, the control logic activates the internal circuitry. The
IC then waits for the PROTECT pin to reach V
det(PROTECT) +
V
det(hys)PROTECT
, the CTRL pin
to reach V
startup(CTRL)
, and the mains voltage to increase to above the brownin level.
When all these conditions are met, the soft start capacitor on the ISENSE pin (C
SS
in
Figure 3
) is charged. The system starts switching. In a typical application, the supply
voltage is taken over by the auxiliary winding of the transformer.
During the start-up period, the VCC pin is continuously regulated to the V
startup
level using
the HV charge current until the output voltage is at its regulation level, which is detected
via the CTRL pin. In this way the VCC capacitor value can be limited. Due to the limited
current capability from the HV pin and depending on the mains voltage, the voltage on pin
VCC can still drop slightly during the start-up period.
Fig 3. Typical TEA18361LT configuration
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