ON Semiconductor NCP1351B, Application Note

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©
Semiconductor Components Industries, LLC, 2015
May, 2015 − Rev. 2
1 Publication Order Number:
AND8344/D
AND8344/D
Implementing an LCD TV
Power Supply with
the NCP1392B, NCP1606
and NCP1351B
Overview
The following reference document describes a built and
tested, GreenPoint
®
solution for an LCD TV power supply.
The reference design circuit consists of one single-sided
171
×
200 mm printed circuit board with a height of only
30 mm. The compact size allows the design to fit into the
frame of an LCD TV. An overview of the entire circuit is
provided in Figure 1. Careful consideration was given to
optimizing the performance while minimizing total solution
cost.
EMI
Filter
NCP1606
PFC
Controller
24V/6A
NCP1392
Resonant Converter
+
Half Bridge Driver
TL431
5V/4A
Bias
Output
NCP1351
SMPS
Regulator
24V/6A
5V/2A(STB)
EN
12V/3A
12V/3A
5V/2A
Resonant Technology
for Increased
Efficiency and Lower EMI
Cost Effective Critical
Conduction Mode Power
Factor Controller
Highly Integrated
Current Mode
SMPS Regulator
Start
Standby
or
Figure 1. LCD TV Demo Board
85V − 265Vac
TL431
LCD Power Supply Requirements
In large flat panel displays (FPD) (> 32
″
), the power
supply is generally internal and requires anywhere from 120
to 500 W depending on the size of the TV and the feature set.
Several voltage rails are needed to supply the different
blocks such as backlighting, audio amplification, tuner and,
image signal processing etc. Because the input power is
above 75 W, the application has to be compliant with the
IEC1000−3−2 class D standard which places regulations on
total harmonic distortion (THD). To meet this regulatory
requirement, the NCP1606 active power factor correction
front end is used. The PFC is designed to cope with universal
mains (85 to 265 V ac, 47−63 Hz) to allow for one power
supply to be used for any region. Also, an auxiliary supply
based on the NCP1351 is needed to supply 5 V to the
microcontroller which must remain biased even in standby
mode.
Low power consumption in standby mode is a key
requirement in today’s LCD TVs. Recent studies have
indicated that in the average EU household, between 5% and
10% of its total yearly electricity consumption is due to the
standby mode of consumer electronics equipment and other
apparatus. TV sets are obviously one of the biggest
contributors. As a result there are various voluntary and
mandatory energy regulation standards that vary by country
and region.
APPLICATION NOTE
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