Datasheet

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REV.: 0/2019 P-4
Reference Design
Specifi cations (measured @ Ta= 25°C, full load after warm up unless otherwise stated)
R-REF04-RIA12
Background to RIA12 Requirements
The R-REF04-RIA12 reference designs include a RIA12-conform surge stopper circuit. RIA12 is a legacy railway standard that precedes the
current EN50155 standard, but is still relevant for older rail installations. The maximum surge voltage according to RIA12 is 3.5x the nominal input
voltage, much higher than the EN50155 limit of 1.4x the nominal input voltage. Due to the very low source impedance and relatively long duration
of 20ms, RIA12 surges cannot be easily blocked with an input fi lter. An active input voltage clamp is required, which has been incorporated in the
R-REF04-RIA12 reference design.
The surge voltages are defi ned in the RIA Specifi cation No 12:
Wave
Form
Type of Disturbance Voltage Level
U
(minimum)
Duration
d
(Maximum)
Duration
D
(Minimum)
Series Resistor
R
s
(±10% Tolerance)
A
B
Supply Related Surge
3.5 x V
nom.
1.5 x V
nom.
2.0ms
0.1s
20ms
1.0s
0.2Ω
0.2Ω
C
D
E
F
G
Direct Transcient
800V
1500V
3000V
4000V
7000V
10µs
5µs
0.5µs
0.1µs
0.05µs
100µs
50µs
5µs
1µs
0.1µs
5Ω
5Ω
100Ω
100Ω
100Ω
H
J
K
L
Indirect Coupled Transcient
1500V
3000V
4000V
7000V
5µs
0.5µs
0.1µs
0.05µs
50µs
5µs
1µs
0.1µs
100Ω
100Ω
100Ω
100Ω
V
nom.
= nominal Voltage
VOLTAGE
WAVEFORM
GENERATOR
TO ELECTRONIC
EQUIPMENT
UNDER TEST
VOLTAGE
U
VOLTAGE
U
U
0.9
U
0.5
U
>
> > >
U
0.1
D
d d
TIME
R
S