SSL21083AT Datasheet, PDF (6/23 Pages) NXP Semiconductors – Compact non-dimmable LED driver IC

NXP Semiconductors
SSL21083AT
Compact non-dimmable LED driver IC
8. Functional description
8.1 Converter operation
The converter in the SSL21083AT is a Boundary Conduction Mode (BCM), peak current
controlled system. Figure 3 shows the basic application diagram. Figure 4 shows the
waveforms. This converter type operates at the boundary between continuous and
discontinuous mode. Energy is stored in inductor L each period that the switch is on. The
inductor current I_L is zero when the internal MOSFET switch is switched on. Thereafter,
the amplitude of the current build-up in L is proportional to V_IN V_OUT and the time that
the internal MOSFET switch is on. When the internal MOSFET switch is switched off, the
current continues to flow through the freewheel diode and the output capacitor. The
current then falls at a rate proportional to the value of V_OUT. The LED current I_LED is
almost equal to half the peak switch current. As soon as the inductor current I_L is zero, a
new cycle is started.
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Fig 3. Basic SSL21083AT application diagram
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SSL21083AT
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6 — 4 October 2013
© NXP B.V. 2013. All rights reserved.
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