Q8008L5 Datasheet, PDF (179/223 Pages) Teccor Electronics – Thyristor Product Catalog

AN1008
8
Explanation of Maximum Ratings and
Characteristics for Thyristors
Introduction
Data sheets for SCRs and triacs give vital information regarding
maximum ratings and characteristics of thyristors. If the maxi-
mum ratings of the thyristors are surpassed, possible irrevers-
ible damage may occur. The characteristics describe various
pertinent device parameters which are guaranteed as either min-
imums or maximums. Some of these characteristics relate to the
ratings but are not ratings in themselves. The characteristic does
not define what the circuit must provide or be restricted to, but
defines the device characteristic. For example, a minimum value
is indicated for the dv/dt because this value depicts the guaran-
teed worst-case limit for all devices of the specific type. This min-
imum dv/dt value represents the maximum limit that the circuit
should allow.
Maximum Ratings
V_RRM: Peak Repetitive Reverse Voltage — SCR
The peak repetitive reverse voltage rating is the maximum peak
reverse voltage that may be continuously applied to the main ter-
minals (anode, cathode) of an SCR. (Figure AN1008.1) An open-
gate condition and gate resistance termination is designated for
this rating. An increased reverse leakage can result due to a pos-
itive gate bias during the reverse voltage exposure time of the
SCR. The repetitive peak reverse voltage rating relates to case
temperatures up to the maximum rated junction temperature.
+I
Voltage Drop (V_T) at
Specified Current (i_T)
Latching Current (I_L)
Reverse Leakage
Current - (I_RRM) at
Specified V_RRM
-V
Minimum Holding
Current (I_H)
Specified Minimum
Reverse Blocking
Voltage (V_RRM)
Off - State Leakage
Current - (I_DRM) at
Specified V_DRM
+V
Specified Minimum
Off - State
Blocking
Voltage (V_DRM)
Figure AN1008.1
Reverse
Breakdown
Voltage
-I
Forward
Breakover
Voltage
V-I Characteristics of SCR Device
V_DRM: Peak Repetitive Forward (Off-state) Voltage
SCR
The peak repetitive forward (off-state) voltage rating (Figure
AN1008.1) refers to the maximum peak forward voltage which
may be applied continuously to the main terminals (anode, cath-
ode) of an SCR. This rating represents the maximum voltage the
SCR should be required to block in the forward direction. The
SCR may or may not go into conduction at voltages above the
V_DRM rating. This rating is specified for an open-gate condition
and gate resistance termination. A positive gate bias should be
avoided since it will reduce the forward-voltage blocking capabil-
ity. The peak repetitive forward (off-state) voltage rating applies
for case temperatures up to the maximum rated junction temper-
ature.
Triac
The peak repetitive off-state voltage rating should not be sur-
passed on a typical, non-transient, working basis. (Figure
AN1008.2) V_DRM should not be exceeded even instantaneously.
This rating applies for either positive or negative bias on main
terminal 2 at the rated junction temperature. This voltage is less
than the minimum breakover voltage so that breakover will not
occur during operation. Leakage current is controlled at this volt-
age so that the temperature rise due to leakage power does not
contribute significantly to the total temperature rise at rated cur-
rent.
+I
Voltage Drop (V_T) at
Specified Current (i_T)
Minimum Holding
Current (I_H)
-V
Latching Current (I_L)
Off-state Leakage
Current – (I_DRM) at
Specified V_DRM
+V
Specified Minimum
Off-state
Blocking
Voltage (V_DRM)
Figure AN1008.2
Breakover
Voltage
-I
V-I Characteristics of Triac Device
©2002 Teccor Electronics
Thyristor Product Catalog
AN1008 - 1
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