TEA18363T

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Product data sheet

Rev. 2 — 12 December 2013

7 of 27

NXP Semiconductors

TEA18363T

GreenChip SMPS control IC

At high output power the converter operates in quasi-resonant mode. The next converter

cycle starts after demagnetization of the transformer and detection of the valley. In

quasi-resonant mode switching losses are minimized because the external MOSFET is

switched on while the drain-source voltage is minimal.

To prevent high-frequency operation at lower loads, the quasi-resonant operation

switches to Discontinuous Conduction Mode (DCM) operation with valley skipping once

the frequency reaches its maximum. This frequency limit reduces the MOSFET switch-on

losses and conducted EMI.

At medium power levels, the controller enters Frequency Reduction (FR) mode. A Voltage

Controlled Oscillator (VCO) controls the frequency. The minimum frequency in this mode

is reduced to 25 kHz. During FR mode, the primary peak current is kept at an adjustable

minimum level to maintain high efficiency. Valley switching is also active in this mode.

At low power, the converter enters the burst mode. In burst mode, the minimum switching

frequency is 25 kHz.

7.3 Supply management

All internal reference voltages are derived from a temperature compensated on-chip band

gap circuit. Internal reference currents are derived from a trimmed and

temperature-compensated current reference circuit.

Fig 5.

Modes of operation