EDN_2012_i08.pdf
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Pobierz
APRI L
19
Tales from the Cube:
Smack attack Pg 58
Issue 8/ 2 012
www.edn.com
Baker’s Best Pg 18
The significance of
poles and zeros Pg 20
Design Ideas Pg 46
Shipping now:
conflict-free parts Pg 52
ConTroller ICs Take
mulTITouCh sCreens
BeYonD
smarTphones
Page 30
pico-projector design uses color leDs
Page 23
Teardown: the nuances of variable-frequency drives
Page 41
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Constant LED Current Regulation
IRS2980 Features
• Internal high voltage regulator
• Hysteretic current control
• High side current sensing
• PWM dimming with analog or PWM
control input
• Free running frequency with maximum
limiting (150kHz)
EMI Filter
Rectifier
IC and Switches
LEDs
Line
IC
IRPLLED7 Demo Board
IRS2980 Benefi ts
• Low component count
• Off-line operation
• Very simple design
• Inherent stability
• Inherent short circuit protection
IRPLLED7 Demo Board
LED Current vs Input Voltage
390
380
370
360
350
340
Demo Board Specifi cations
• Input Voltage 70V to 250V (AC)
• Output Voltage 0V to 50V (DC)
• Regulated Output Current: 350mA
• Power Factor > 0.9
• Low component count
• Dimmable 0 to 100%
• Non-isolated Buck regulator
LED Current (mA)
330
LED
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™
IRS2980
320
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Input Voltage
Part
Number
Gate
Drive Current
Startup
Current
Package
Voltage
Frequency
IRS2980S
SO-8
450V
+180 / -260 mA
<250 µA
<150 kHz
IRS25401S
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+500 / -700 mA
<500 µA
<500 kHz
IRS25411S
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+500 / -700 mA
<500 µA
<500 kHz
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contents
4.19.12
Pico-projector design
uses color leDs
23
An LED light source uses a flexible
chip and package platform for col-
or-sequential embedded pico projection.
by Francis Nguyen and Stefan Morgott,
Osram Opto Semiconductors GmbH
Teardown:
the nuances
of variable-
frequency
drives
41
Get an
Controller iCs take multitouch
screens beyond smartphones
30
As multitouch touchscreens move beyond smart-
phones and tablets into automotive, medical,
and instrumentation applications, their features
evolve to fit lower prices and varying form factors.
by Margery Conner, Senior Technical Editor
inside view
of induction-motor
control by varying
frequency using PWM.
by Steve Taranovich,
Senior Technical Editor
Cover
image: ThinkSToCk/giulia Fini-guloTTa
Design
iDeas
R
4
10k
46
Convert 1 to 5V signal to 4- to 20-mA output
12V
R
5
10k
47
Linearize optical distance sensors with a voltage-to-frequency converter
6
8
IC
2
TL072
50
Use a transistor as a heater
7
5
51
Monitor circuit conserves battery energy
4
▶
Find out how to submit your own Design Idea: http://bit.ly/DesignIdeasGuide.
–12V
[
www.edn.com
]
APRIL 19, 2012 |
EDN
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