TEA1721AT Datasheet, PDF (6/14 Pages) NXP Semiconductors – Ultra-low standby SMPS controller with integrated power switch

NXP Semiconductors
TEA1721AT
Ultra-low standby SMPS controller with integrated power switch
5.3.3 Constant Current mode (CC)
The CC mode starts at maximum power delivery and keeps the output current constant for
decreasing output voltage.
CC mode is enabled when the converter is operating at the maximum switching
frequency, with the maximum primary peak current when the FB voltage drops below the
regulated level.
CC mode operation controlled is by regulation of the switching frequency from 50.5 kHz
down to 25 kHz and by I_SOURCE regulation from the maximum V_SOURCE level of 555 mV
until level of V_SOURCE is 0.18 V. The V_SOURCE level of 0.18 V equals the level at start-up
with zero output voltage and the output capacitor discharged.
5.4 Jitter
The TEA1721 features a jitter function for ElectroMagnetic Interference (EMI) reduction.
The switching frequency varies between –8 % and +8 % for the spread spectrum. The
sweep frequency is a low frequency of approximately 200 Hz. To keep the output power
constant, the V_SOURCE level is jittered with the opposite polarity. The jitter is active in all
operation modes except burst mode.
TEA1721AT
Preliminary data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 24 January 2012
© NXP B.V. 2012. All rights reserved.
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