1
Application Note
©2020 Littelfuse Inc.Littelfuse.com
High Power Semiconductor Crowbar
Protector for AC Power Line Applications
Power Input Line Risks and Protection
AC power line disturbances are the cause of many equipment failures. The damage can be as elusive as occasional data loss or as
dramatic as the destruction of a power supply, LED Lighting, Industrial system and consumer equipment such as ovens or refrigerators
and television sets.
Power line disturbances go by many names---transients, surges, spikes, glitches, etc. But regardless of the specific name, an
understanding of their characteristics and the operation of the various protection components available is necessary to design an
effective protection circuit.
There are some popular protection components for these power input lines. The most common over voltage protection components
are MOVs (Metal Oxide Varistor), high power TVS (Transient Voltage Suppression) Diodes and GDTs (Gas Discharge Tube). In this article,
we are going to discuss a new and innovative method of using a silicon crowbar component known as, the SIDACtor
®
Protection
Thyristor, for the main over voltage protection solution for AC power lines.
Surge Protection
Surge protection components can be divided into two basic types: Crowbar type devices such as GDTs and protection thyristor type
SIDACtor
®
components and clamp type components such as TVS diodes, MOVs etc.
The clamp type components have faster response time but are limited in their current handling ability because the transient energy
must be dissipated by the clamping component. Also, the voltage drop across a clamp type component increases as a function of the
conducted current passing through it. Thus a higher clamping voltage threshold component will have a lower peak current capability.
(The power rating remains the same for all components in a particular series but since power is the product of the voltage and current,
an increasing voltage demands a decrease of current).
A crowbar type component can handle much higher surge current because during their on-state condition, the voltage across the
component is extremely low. These crowbarring components act as a “near short circuit value” path shunting the transient energy
away from the protected equipment. And this, low on-state voltage will further reduce any electrical over stress to the protected circuit.
SIDACtor
®
Component in AC Power Line Protection
Questions may arise due to the nature of the SIDACtor
®
component being a crowbar protection and its compatibility with an AC power
source. This article will review the design parameters for selecting a SIDACtor
®
component for AC power line protection. Please note
that this discussion of the SIDACtor
®
component use is confined to AC power line only; it is not compatible for high current DC supply
ports. The SIDACtor
®
component will reset on an AC port at the zero-crossing every half-cycle for an AC signal. However, for high
current DC power lines, the SIDACtor
®
component will not reset if the short circuit current available is higher than its holding current
parameter. Of course if you connect the SIDACtor
®
component with TVS or MOV in series, it can be used on DC power line too. TVS or
MOV Vbr should be equal or higher than DC max voltage
2
Application Note
©2020 Littelfuse Inc.Littelfuse.com
Littelfuse Pxxx0FNL and Pxxx0ME Series SIDACtor
®
Component
The Littelfuse Pxxx0FNL and Pxxx0ME Series high energy SIDACtor
®
component has a crowbarring characteristic, which offers low on-
state voltage values that are much lower than the arc voltage of the traditional GDT and it offers a much lower voltage threshold than
the clamping voltage of an MOV. Compared to clamping silicon TVS diodes, the Pxxx0FNL and Pxxx0ME SIDACtor
®
component can
handle a much higher surge current since its on-state-voltage is so low. It also provides a much lower over-shoot characteristic for high
dv/dt or high di/dt events as compared to the GDT, MOVs or TVS components.
The Pxxx0FNL and Pxxx0ME series have component working voltage (VDRM) (also known as off-state voltage) ranging from 58v
to 450v. Referring to the IPP surge current and ITSM table, the Pxxx0ME provides 5000A 8/20 IPP (peak pulse current rating) and a
minimum 400A ITSM for 50/60Hz AC single cycle sinusoidal wave surge event and Pxxx0FNL provides 3000A 8/20 IPP and a minimum
300A ITSM for 50/60Hz AC single cycle sinusoidal wave surge event.
Product Series of Pxxx0ME Series in TO-218
Surge I
PP
and I
TSM
Part Number Marking
V
DRM
@ I
DRM
=5µA V
s
@ 100V/us
V
min
V
max
P1500MEL P1500ME 140 180
P1900MEL P1900ME 155 220
P2300MEL P2300ME 180 260
P3800MEL P3800ME 350 430
P4800MEL P4800ME 450 600
I
PP
I
TSM
50/60 Hz
8/20
1
1.2x50
2
A
min
A
min
5000
3
400
Pxxx0ME Series in TO-218
Product Series of Pxxx0FNL Series in TO-262M
Surge I
PP
and I
TSM
Part Number Marking
V
DRM
@ I
DRM
=5µA V
s
@ 100V/us
V
min
V
max
P0640FNL P0640FN 58 77
P0720FNL P0720FN 65 88
P0900FNL P0900FN 75 98
P1100FNL P1100FN 90 130
P1300FNL P1300FN 120 160
P1500FNL P1500FN 140 180
P1900FNL P1900FN 155 220
P2300FNL P2300FN 180 260
P2600FNL P2600FN 220 300
P3100FNL P3100FN 275 350
P3500FNL P3500FN 320 400
P3800FNL P3800FN 350 430
I
PP
I
TSM
50/60 Hz
8/20
1
1.2x50
2
A
min
A
min
3000 300
Pxxx0FNL Series in TO-262M
Notes:
1. Current waveform is µs
2. Voltage waveform is µs
3. P1500MEL to P2300MEL have surge rating of 5kA @ 8/20. For surge rating of P3800MEL, it
is a minimum 4kA and typical 5kA@8/20μs.
Notes:
1. Current waveform is µs
2. Voltage waveform is µs