PRF21BB471QB5RA Murata, PRF21BB471QB5RA Datasheet - Page 8

• Manufacturer Part Number: PRF21BB471QB5RA
• Description: Thermistors - PTC 470 Ohm 50% 32volts
• Manufacturer: Murata
• Type: PTCr

Specifications of PRF21BB471QB5RA

• Resistance: 470 Ohms
• Tolerance: 50 %
• Termination Style: SMD/SMT
• Operating Temperature Range: - 20 C to + 130 C
• Dimensions: 1.25 mm W x 2 mm L x 0.9 mm H
• Voltage: 32 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1. Protective Threshold Current
2. Protective Threshold Current Range
3. Operating Time
6
!Note
Basic Characteristics of POSISTORr
The maximum current value is called the "Protective
Threshold Current" for Voltage vs. Current characteristics
(static).
When smaller than the protective threshold current flows
in POSISTORr, it reaches its stability (as shown in figure
on right) at the intersection (A) of the load curve (a) and
voltage-current characteristics of POSISTORr(c). And
POSISTORr works as a normal fixed resistor.
However, when larger than protective threshold current
flows, it stabilizes at the intersection (B) with the load
curve (b).
Protective threshold current varies depending on the
ambient temperature, resistance value, temperature
characteristics and shape. (see Figure on right) The
maximum value of trip current and the minimum value of
the hold current are in the range of ambient temperature
-10 to +60 C.
That is, when a current is smaller than the hold current,
POSISTORr works only as a fixed resistor. When larger
than the trip current flows, however, POSISTORr
protects the circuit from overload.
A period starting from the voltage input to the moment
current itself sharply attenuates is called "Operating
Time." Conventionally, operation time (t
to be the period until inrush current (I
level one half the original inrush current (I
• Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this catalog to prevent smoking and/or burning, etc.
• This catalog has only typical specifications because there is no space for detailed specifications. Therefore, please review our product specifications or consult the approval sheet for product specifications before ordering.
Technical Terms
0
) decreases to a
0
) is determined
0
/2).
Load Curve of Circuit and Voltage - Current Characteristics
of POSISTORr
Protective Threshold Current Range
Operating Current
E
I =
1000
E - Vp
800
600
400
200
Vp
R
0
L
Protective Threshold Current
-20
I
I
2
Ambient Temperature ( C)
0
0
I
R
0
L
Hold Current
t
20
0
Time (sec.)
b
a
Trip Current
a
b
c
40
Load curve in normal state
(normal current)
Load curve in abnormal state
(abnormal current)
Voltage-current characteristics
of POSISTORr
A
Operating Time
Voltage (log)
60
c
E
B
Apr.25,2011
R90E.pdf