PRF18BA471QB5RB Datasheet, PDF (13/104 Pages) Murata Manufacturing Co., Ltd. – POSISTOR for Circuit Protection

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R90E.pdf
Sep.24,2012
Application Notes
c Current Limiter for LED
Chip POSISTORr: PRG series
1. Applications
POSISTORr is an effective current limit solution based
on LED's allowable current and temperature
characteristics.
(1) LED lighting instruments
(2) LED backlight of flat displays
See below figures.
IC
IC
Protected by
POSISTORr
Higher brightness vs.
a fixed resistor
LED Driving Circuit
Allowable LED
Working Zone
Ambient Temp.
Allowable LED
Working Zone
Ambient Temp.
Current Limit by
a fixed resistor
LED Current
2. Benefits
(1) Higher LED brightness versus a fixed resistor. LED
can work in the smaller series resistance with
POSISTORr at normal operation temperature. The
number of LEDs is possibly reduced.
(2) LED lifetime may be extended due to the current
limiting function of the POSISTORr in cases of
overheat or overcurrent situation.
(3) Small 0805 package allows the POSISTORr to be
placed close to the LED. It offers accurate detection of
ambient temperature near LED and increases
flexibility of packaging.
3. Recommended part numbers
Choose an appropriate part number having max. voltage
and resistance value. Review the protective threshold
current range based on the operating current and
temperature of the LED.
Part Number
PRG21BC0R6MM1RA
PRG21BC0R2MM1RA
PRG21BC1R0MM1RA
PRG21BC2R2MM1RA
PRG21BC3R3MM1RA
PRG21BC6R8MM1RA
PRG21BC4R7MM1RA
Max.
Voltage
(V)
6
6
12
16
20
30
30
Max.
Current
(A)
10
10
10
6.5
6.0
3.5
5.0
Hold Current
(at +60 °C)
(mA)
285
500
220
150
120
80
100
Trip Current
(at -10 °C)
(mA)
1100
2000
850
600
480
320
400
*Curie Point means the temperature at which the resistance value reaches twice the resistance at 25°C.
Please ask for details.
Resistance
(at +25 °C)
(ohm)
0.6 ±20%
0.2 ±20%
1.0 ±20%
2.2 ±20%
3.3 ±20%
6.8 ±20%
4.7 ±20%
Curie Point
(°C) *
90
90
90
90
90
90
90
More
Details
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