Maximum Ratings and Characteristics for Teccor - Digi-Key

Teccor® brand Thyristors
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 maximum ratings of the Thyristors
are surpassed, possible irreversible damage may occur.
The characteristics describe various pertinent device
parameters which are guaranteed as either minimums 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
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because this value depicts the guaranteed worst-case limit
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value represents the maximum limit that the circuit should
allow.
Maximum Ratings
VRRM: 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 terminals (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 positive 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.
(anode, cathode) 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 VDRM 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 capability. The
peak repetitive forward (off-state) voltage rating applies
for case temperatures up to the maximum rated junction
temperature.
Triac
The peak repetitive off-state voltage rating should not
be surpassed on a typical, non-transient, working basis.
(Figure AN1008.2) VDRM 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 voltage so
that the temperature rise due to leakage power does not
contribute significantly to the total temperature rise at
rated current.
+I
Voltage Drop (vT) at
Specified Current (iT)
Latching Current (IL)
Minimum Holding
Current (IH)
-V
+V
+I
Specified Minimum
Off-state
Blocking
Voltage (VDRM)
Voltage Drop (vT) at
Specified Current (iT)
Reverse Leakage
Current - (IRRM) at
Specified VRRM
Off-state Leakage
Current – (IDRM) at
Specified VDRM
Latching Current (IL)
-I
Off - State Leakage
Current - (IDRM) at
Specified VDRM
Minimum Holding
Current (IH)
Figure AN1008.2
-V
Breakover
Voltage
V-I Characteristics of Triac Device
+V
IT: Current Rating
Specified Minimum
Off - State
Blocking
Voltage (VDRM)
Specified Minimum
Reverse Blocking
Voltage (VRRM)
Reverse
Breakdown
Voltage
Figure AN1008.1
-I
Forward
Breakover
Voltage
V-I Characteristics of SCR Device
VDRM: 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
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.
SCR
For RMS and average currents, the restricting factor is
usually confined so that the power dissipated during the
on state and as a result of the junction-to-case thermal
resistance will not produce a junction temperature in
excess of the maximum junction temperature rating.
Power dissipation is changed to RMS and average current
ratings for a 60 Hz sine wave with a 180º conduction angle.
The average current for conduction angles less than 180º
is derated because of the higher RMS current connected
with high peak currents. The DC current rating is higher
than the average value for 180º conduction since no RMS
component is present.
Explanation of Maximum Ratings and Characteristics for Thyristors
AN1008
AN1008
Teccor® brand Thyristors
AN1008
PD =
TJ(MAX)–TC
RRJC
where TJ(max) is the maximum rated junction temperature
(at zero rated current), TC is the actual operating case
temperature, and RRJC is the published junction-to-case
thermal resistance. Transient thermal resistance curves are
required for short interval pulses.
Triac
The limiting factor for RMS current is determined by
multiplying power dissipation by thermal resistance. The
resulting current value will ensure an operating junction
temperature within maximum value. For convenience,
dissipation is converted to RMS current at a 360º
conduction angle. The same RMS current can be used at
a conduction angle of less than 360º. For information on
non-sinusoidal waveshapes and a discussion of dissipation,
refer to the preceding description of SCR current rating.
ITSM: Peak Surge (Non-repetitive) On-state Current -SCR and Triac
The peak surge current is the maximum peak current
that may be applied to the device for one full cycle of
conduction without device degradation. The maximum
peak current is usually specified as sinusoidal at 50 Hz or
60 Hz. This rating applies when the device is conducting
rated current before the surge and, thus, with the junction
temperature at rated values before the surge. The junction
temperature will surpass the rated operating temperature
during the surge, and the blocking capacity may be
decreased until the device reverts to thermal equilibrium.
The surge-current curve in Figure AN1008.3 illustrates the
peak current that may be applied as a function of surge
duration. This surge curve is not intended to depict an
exponential current decay as a function of applied overload.
Instead, the peak current shown for a given number of
cycles is the maximum peak surge permitted for that
time period. The current must be derated so that the peak
junction temperature during the surge overload does not
exceed maximum rated junction temperature if blocking is
to be retained after a surge.
SUPPLY FREQUENCY: 60 Hz Sinusoidal
LOAD: Resistive
RMS ON-STATE CURRENT [ I T(RMS)]:
Maximum Rated Value at Specified
Case Temperature
1000
Peak Surge (Non-repetitive)
On-state Current (I TSM ) – Amps
The dissipation for non-sinusoidal waveshapes can
be determined in several ways. Graphically plotting
instantaneous dissipation as a function of time is one
method. The total maximum allowable power dissipation
(PD) may be determined using the following equation for
temperature rise:
400
300
250
40 A
TO
- 2 18
150
120
100
80
25 A
T0-2
Notes:
1) Gate control may be lost
during and immediately
following surge current interval.
2) Overload may not be repeated
until junction temperature has
returned to steady-state
rated value.
20
60
50
40
15 A
TO
30
-220
20
10
1
10
100
1000
Surge Current Duration – Full Cycles
Figure AN1008.3
Peak Surge Current versus Surge Current
Duration
ITM: Peak Repetitive On-state Current – SCR and Triac
The ITM rating specifies the maximum peak current that
may be applied to the device during brief pulses. When
the device operates under these circumstances, blocking
capability is maintained. The minimum pulse duration
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operating voltage, the duty factor, the case temperature,
and the gate waveform are also defined. This rating
must be followed when high repetitive peak currents
are employed, such as in pulse modulators, capacitivedischarge circuits, and other applications where snubbers
are required.
di/dt: Rate-of-change of On-state Current – SCR
and Triac
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current through a Thyristor device during turn-on. The value
of principal voltage prior to turn-on and the magnitude and
rise time of the gate trigger waveform during turn-on are
among the conditions under which the rating applies. If
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localized heating may cause device degradation.
During the first few microseconds of initial turn-on, the
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the Thyristor is greatly increased as soon as the total area
of the pellet is in full conduction.
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or transient turn-on (non-gated) is not related to this
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temperature.
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can be calculated by means of the following equation.
di ITM
---- = ----dt 2t1
Explanation of Maximum Ratings and Characteristics for Thyristors
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.
Teccor® brand Thyristors
VDM = Off-state voltage
prior to switching
di = ITM
dt
2 t1
50%
IDRM: Peak Repetitive Off-state (Blocking) Current
10%
0
t
t1
Time
Figure AN1008.4
Relationship of Maximum Current Rating to
Time
I2t Rating -- SCR and Triac
The I2t rating gives an indication of the energy-absorbing
capability of the Thyristor device during surge-overload
conditions. The rating is the product of the square of the
RMS current (IRMS)2 that flows through the device and the
time during which the current is present and is expressed
in A2s. This rating is given for fuse selection purposes. It is
important that the I2t rating of the fuse is less than that of
the Thyristor device. Without proper fuse or current limit,
overload or surge current will permanently damage the
device due to excessive junction heating.
PG: Gate Power Dissipation -- SCR and Triac
Gate power dissipation ratings define both the peak power
(PGM) forward or reverse and the average power (PG(AV) )
that may be applied to the gate. Damage to the gate can
occur if these ratings are not observed. The width of the
applied gate pulses must be considered in calculating the
voltage and current allowed since the peak power allowed
is a function of time. The peak power that results from a
given signal source relies on the gate characteristics of the
specific unit. The average power resulting from high peak
powers must not exceed the average-power rating.
TS, TJ: Temperature Range -- SCR and Triac
The maximum storage temperature (TS) is greater than
the maximum operating temperature (actually maximum
junction temperature). Maximum storage temperature
is restricted by material limits defined not so much by
the silicon but by peripheral materials such as solders
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encapsulating epoxy. The forward and off-state blocking
capability of the device determines the maximum junction
(TJ) temperature. Maximum blocking voltage and leakage
current ratings are established at elevated temperatures
near maximum junction temperature; therefore, operation
in excess of these limits may result in unreliable operation
of the Thyristor.
Characteristics
VBO: Instantaneous Breakover Voltage -- SCR and Triac
Breakover voltage is the voltage at which a device turns
on (switches to on state by voltage breakover). (Figure
AN1008.1) This value applies for open-gate or gate©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.
SCR
IDRM is the maximum leakage current permitted through
the SCR when the device is forward biased with rated
positive voltage on the anode (DC or instantaneous) at
rated junction temperature and with the gate open or
gate resistance termination. A 1000 Ω resistor connected
between gate and cathode is required on all sensitive
SCRs. Leakage current decreases with decreasing junction
temperatures. Effects of the off-state leakage currents on
the load and other circuitry must be considered for each
circuit application. Leakage currents can usually be ignored
in applications that control high power.
Triac
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for the Triac is the same as for the SCR except that it
applies with either positive or negative bias on main
terminal 2.(Figure AN1008.2)
IRRM: Peak Repetitive Reverse Current – SCR
This characteristic is essentially the same as the peak
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voltage is applied to the anode (reverse biased).
VTM: Peak On-State Voltage -- SCR and Triac
The instantaneous on-state voltage (forward drop) is the
principal voltage at a specified instantaneous current and
case temperature when the Thyristor is in the conducting
state. To prevent heating of the junction, this characteristic
is measured with a short current pulse. The current pulse
should be at least 100 μs duration to ensure the device
is in full conduction. The forward-drop characteristic
determines the on-state dissipation. See Figure AN1008.5,
and refer to “IT: Current Rating” on page AN1008-2.
Positive or Negative
Instantaneous On-state Current (iT) – Amps
Current
ITM
resistance termination. Positive gate bias lowers the
breakover voltage. Breakover is temperature sensitive and
will occur at a higher voltage if the junction temperature
is kept below maximum TJ value. If SCRs and Triacs are
turned on as a result of an excess of breakover voltage,
instantaneous power dissipations may be produced that
can damage the chip or die.
90
80
TC = 25 °C
70
40 A TO-218
60
50
40
30
20
10
Figure AN1008.5
0
15 and 25 A TO-220
0
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Positive or Negative
Instantaneous On-state Voltage (vT) – Volts
On-state Current versus On-state Voltage
(Typical)
Explanation of Maximum Ratings and Characteristics for Thyristors
AN1008
AN1008
Teccor® brand Thyristors
AN1008
IGT: DC Gate Trigger Current
VGT: DC Gate Trigger Voltage
SCR
SCR
IGT is the minimum DC gate current required to cause
the Thyristor to switch from the non-conducting to the
conducting state for a specified load voltage and current
as well as case temperature. The characteristic curve
illustrated in Figure AN1008.6 shows that trigger current
is temperature dependent. The Thyristor becomes less
sensitive (requires more gate current) with decreasing
junction temperatures. The gate current should be
increased by a factor of two to five times the minimum
threshold DC trigger current for best operation. Where
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temperatures are expected, the gate pulse may be 10
times the minimum IGT, plus it must be fast-rising and of
sufficient duration in order to properly turn on the Thyristor.
VGT is the DC gate-cathode voltage that is present just
prior to triggering when the gate current equals the DC
trigger current. As shown in the characteristic curve in
Figure AN1008.8, the gate trigger voltage is higher at lower
temperatures. The gate-cathode voltage drop can be higher
than the DC trigger level if the gate is driven by a current
higher than the trigger current.
Triac
The difference in VGT for the SCR and the Triac is that the
Triac can be fired in four possible modes. The threshold
trigger voltage can be slightly different, depending on
which of the four operating modes is actually used.
2.0
V GT
V GT (T J = 25 °C)
3.0
1.5
1.0
Ratio of
I GT
Ratio of
I GT (T J = 25 °C)
4.0
2.0
.5
0
1.0
-65
-40
-15
+25
+65
+125
Junction Temperature (T J) – °C
Figure AN1008.8
0
-65
-15
+25
+65
Junction Temperature (T J) – °C
-40
Figure AN1008.6
+125
IL: Latching Current
Normalized DC Gate Trigger Current for All
Quadrants versus Case Temperature
Triac
The description for the SCR applies as well to the Triac
with the addition that the Triac can be fired in four possible
modes (Figure AN1008.7):
Quadrant I (main terminal 2 positive, gate positive)
Quadrant II (main terminal 2 positive, gate negative)
Quadrant III (main terminal 2 negative, gate negative)
Quadrant IV (main terminal 2 negative, gate positive)
ALL POLARITIES ARE REFERENCED TO MT1
MT2
(-)
MT2 POSITIVE
(Positive Half Cycle)
+
IGT
GATE
(+)
IGT
(-)
MT1
IGT
GATE
(+)
MT1
REF
-
+
IGT
MT2
IGT
GATE
MT2 NEGATIVE
(Negative Half Cycle)
MT1
REF
NOTE: Alternistors will not operate in Q IV
Figure AN1008.7
SCR
Latching current is the DC anode current above which the
gate signal can be withdrawn and the device stays on. It
is related to, has the same temperature dependence as,
and is somewhat greater than the DC gate trigger current.
(Figure AN1008.1 and Figure AN1008.2) Latching current is
at least equal to or much greater than the holding current,
depending on the Thyristor type.
Latching current is greater for fast-rise-time anode currents
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dynamic latching current that determines whether a device
will stay on when the gate signal is replaced with very
short gate pulses. The dynamic latching current varies with
the magnitude of the gate drive current and pulse duration.
In some circuits, the anode current may oscillate and drop
back below the holding level or may even go negative;
hence, the unit may turn off and not latch if the gate signal
is removed too quickly.
REF
QII QI
QIII QIV
MT2
MT2
IGT
GATE
MT1
REF
Normalized DC Gate Trigger Voltage for All
Quadrants versus Case Temperature
Definition of Operating Quadrants
Explanation of Maximum Ratings and Characteristics for Thyristors
Triac
The description of this characteristic for the Triac is the
same as for the SCR, with the addition that the Triac can
be latched on in four possible modes (quadrants). Also,
the required latching is significantly different depending
on which gating quadrants are used. Figure AN1008.9
illustrates typical latching current requirements for the four
possible quadrants of operation.
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.
Teccor® brand Thyristors
This value will be reduced by a positive gate signal. This
characteristic is temperature-dependent and is lowest at
the maximum-rated junction temperature. Therefore, the
characteristic is determined at rated junction temperature
and at rated forward off-state voltage which is also a worstcase situation. Line or other transients which might be
applied to the Thyristor in the off state must be reduced, so
that neither the rate-of-rise nor the peak voltage are above
specifications if false firing is to be prevented. Turn-on
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current remains within current ratings of the device being
used.
14
12
I L — mA
10
II
8
6
IV
4
I
III
2
0
1.0
2.0
3.0
4.0
5.0
6.0
I GT — mA
Figure AN1008.9
Critical dv/dt
Typical Triac Latching (IL) Requirements for
Four Quadrants versus Gate Current (IGT)
IH: Holding Current -- SCR and Triac
The holding current is the DC principal on-state current
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state after latching and gate signal is removed. This current
is equal to or lower in value than the latching current
(Figure AN1008.1 and Figure AN1008.2) and is related to
and has the same temperature dependence as the DC gate
trigger current shown in Figure AN1008.10. Both minimum
and maximum holding current may be important. If the
device is to stay in conduction at low-anode currents, the
maximum holding current of a device for a given circuit
must be considered. The minimum holding current of a
device must be considered if the device is expected to
turn off at a low DC anode current. Note that the low DC
principal current condition is a DC turn-off mode, and that
an initial on-state current (latching current) is required to
ensure that the Thyristor has been fully turned on prior to a
holding current measurement.
Ratio of
IH
I H (T J = 25 °C)
4.0
INITIAL ON-STATE CURRENT
= 400 mA dc
3.0
2.0
1.0
0
-65
-40
-15
+25
+65
+125
Junction Temperature (TJ) – °C
Figure AN1008.10
Normalized DC Holding Current versus Case
Temperature
dv/dt, Static: Critical Rate-of-rise of Off-state Voltage
— SCR and Triac
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that a device will hold off, with gate open, without turning
on. Figure AN1008.11 illustrates the exponential definition.
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.
VD
63% of V D
0
t
VD
dv
= 0.63
dt
t
t = RC
Figure AN1008.11
Exponential Rate-of-rise of Off-state Voltage
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dv/dt, Commutating: Critical Rate-of-rise of
Commutation Voltage -- Triac
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the main terminals that a Triac can support (block without
switching back on) when commutating from the on state
in one half cycle to the off state in the opposite half
cycle. This parameter is specified at maximum rated case
temperature (equal to TJ) since it is temperature-dependent.
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peak reapplied voltage (line voltage) and is specified at
rated current and voltage. All devices are guaranteed to
commutate rated current with a resistive load at 50 Hz to
60 Hz. Commutation of rated current is not guaranteed
at higher frequencies, and no direct relationship can be
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higher-frequency operation. With inductive loading, when
the voltage is out of phase with the load current, a voltage
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Triac during the zero-current crossing. (Figure AN1008.12)
A snubber (series RC across the Triac) should be used
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amount below the minimum value which the Triac can be
guaranteed to commutate off each half cycle.
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20% lower while IRMS rating remains the same. (Figure
AN1008.4)
Explanation of Maximum Ratings and Characteristics for Thyristors
AN1008
AN1008
Teccor® brand Thyristors
AN1008
EM
ESOURCE
TIME
IG
di/dt
ITRM
be reapplied. (Figure AN1008.14) Turn-off time is a function
of many parameters and very dependent on temperature
and gate bias during the turn-off interval. Turn-off time
is lengthened for higher temperature so a high junction
temperature is specified. The gate is open during the turnoff interval. Positive bias on the gate will lengthen the turnoff time; negative bias on the gate will shorten it.
IT
(di/dt)C
ITM
Voltage across Triac
10%
50% ITM
63%
VDRM
(dv/dt) C
'JHVSF"/
50% IRM
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Associated Conditions
The tgt is the time interval between the application of
a gate pulse and the on-state current reaching 90% of
its steady-state value. (Figure AN1008.13) As would be
expected, turn-on time is a function of gate drive. Shorter
turn-on times occur for increased gate drives. This turn-on
time is actually only valid for resistive loading. For example,
inductive loading would restrict the rate-of-rise of anode
current. For this reason, this parameter does not indicate
the time that must be allowed for the device to stay on if
the gate signal is removed. (Refer to the description of “IL:
Latching Current” on page AN1008-4.) However, if the load
was resistive and equal to the rated load current value, the
device definitely would be operating at a current above the
dynamic latching current in the turn-on time interval since
current through the device is at 90% of its peak value
during this interval.
90%
Off-state Voltage
10%
90%
10%
Delay
Time
Gate
Trigger
Pulse
Turn-on
Time
Rise
Time
50%
50%
10%
ID Off-State Leakage
iR
Reverse Current
trr
VD
tq
Off-State Voltage
dv/dt
VT
tgt: Gate-controlled Turn-on Time -- SCR and Triac
On-state Current
di/dt
t1
Figure AN1008.14
Waveshapes of tq Rating Test and Associated
Conditions
RθJC, RθJA: Thermal Resistance (Junction-to-case,
Junction-to-ambient) -- SCR and Triac
The thermal-resistance characteristic defines the steadystate temperature difference between two points at a
given rate of heat-energy transfer (dissipation) between
the points. The thermal-resistance system is an analog
to an electrical circuit where thermal resistance is
equivalent to electrical resistance, temperature difference
is equivalent to voltage difference, and rate of heatenergy transfer (dissipation) is equivalent to current.
Dissipation is represented by a constant current generator
since generated heat must flow (steady-state) no matter
what the resistance in its path. Junction-to-case thermal
resistance establishes the maximum case temperature at
maximum rated steady-state current. The case temperature
must be held to the maximum at maximum ambient
temperature when the device is operating at rated current.
Junction-to-ambient thermal resistance is established at a
lower steady-state current, where the device is in free air
with only the external heat sinking offered by the device
package itself. For RRJA, power dissipation is limited by
what the device package can dissipate in free air without
any additional heat sink:
Gate Pulse Width
Figure AN1008.13
Waveshapes for Turn-on Time and Associated
Conditions
RRJC =
tq: Circuit-commutated Turn-off Time -- SCR
The circuit-commutated turn-off time of the device is the
time during which the circuit provides reverse bias to the
device (negative anode) to commutate it off. The turn-off
time occurs between the time when the anode current
goes negative and when the anode positive voltage may
Explanation of Maximum Ratings and Characteristics for Thyristors
RRJA =
TJ–TC
P(AV)
TJ–TA
P(AV)
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com for current information.