SSL21151T NXP [NXP Semiconductors], SSL21151T Datasheet - Page 4

• Manufacturer Part Number: SSL21151T
• Description: Low-cost non-dimmable LED driver IC
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
8. Functional description
SSL2115X
Product data sheet
8.1 Introduction
8.2 Current source operation
The SSL2115X is an integrated circuit intended for retrofit small form factor SSL lamps. It
provides a controller with an internal high-voltage switch to drive LEDs. It operates directly
from the rectified mains.
A flyback inductor is calculated using Equation 1:
Where
I
pk
Fig 3.
•
•
•
•
•
L
=
 is the efficiency of the complete flyback converter
f
U
the output rectifier
L is the primary inductance of the flyback transformer
I
=
sw(high)
pk
max
V
-------------------------- -
--------------------------------------------------------------------
0.85  f
is the peak current through of the flyback transformer
R
ref high
SOURCE
Drain switching wave form
V
t
t
V
V
N = transformer winding turns ratio
V
the maximum combined voltage of the connected LEDs and the voltage drop of
on
off

DRAIN
M
i
OUT
= input voltage

is the high switching frequency
= turn-off time
= turn-on time
= peak voltage

= output voltage.
pk
I

= voltage on pin DRAIN
LED
All information provided in this document is subject to legal disclaimers.
sw high
9
'5$,1


U
max


W
Rev. 2 — 7 June 2012
RQ
0.5 I


pk
2
W
RII
9
0
W
VZ
Low-cost non-dimmable LED driver IC
9
L
 Q9
IUHH UXQQLQJ
RXW
DDD
9
L
SSL2115X
© NXP B.V. 2012. All rights reserved.
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