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| 型號： | AN4840 |
| 英文描述： | Gate triggering and the use of gate characteristics |
| 中文描述： | 門觸發(fā)和特點的門使用 |
| 文件頁數(shù)： | 3/5頁 |
| 文件大小： | 77K |
| 代理商： | AN4840 |
3/5
AN4840 Application Note
www.dynexsemi.com
Time
C
High initial trigger current
Maintaining or back-porch level
dI
g
dt
(To be as fast as possible)
Current - (A)
V
V
OC
(Open circuit voltage)
I
(Short circuit current)
Resistive load line -
Internal resistance = V
OC
I
SC
GATE CHARACTERISTIC
This characteristic is that of the forward biased gate-to-cathode
junction, together with associated on-chip series and parallel
resistors, e.g. gate-to-emitter shorts. The graph shows the upper
limit i.e. highest impedance and lower limit i.e. lowest impedance
for all thyristors of that type likely to be manufactured.
The limits take into account the temperature range
–
40 to
+125
C. All devices will have characteristics between these
limits.
Gate characteristic information is used in conjunction with firing
circuit output load lines to pre-determine operating values of gate
current and voltage - see below.
GATE RATING LIMITS
Thyristors turn on best when Ig and Vg values are well above I
and V
limits - see below. However, peak gate current, gate
voltage and power rating limits should not be exceeded.
V
FGM
- PEAK FORWARD GATE VOLTAGE
If the open circuit voltage of the firing circuit exceeds this
rating (usually 30 volts) there is a danger of internal voltage
breakdown. In practice, 50 or more volts can often be achieved
but is not guaranteed since some internal device constructions
are limited.
I
FGM
- PEAK FORWARD GATE CURRENT
This rating is determined by the current carrying capability of
internal gate leads, bonds and surface metallisation of the
thyristor.
Note that the
‘
X
’
axis of the graph is limited to 10 amps so that
the Ifgm limit of large thyristors is not shown.
P
GM
- PEAK GATE POWER
The average heating effect of the gate current is the issue here.
Thus, a narrow pulse of high P
is as permissible as a wide
pulse of low P
. Included on the graph is a table showing
maximum permitted peak gate power for various pulse widths
and repetition rates. Also on the graph are lines of constant
power. These lines are the power limits corresponding to the
pulse powers given in the table and are used in conjunction with
gate drive load lines.
MATCHING THE GATE DRIVE/FIRING CIRCUIT
TO
THE
THYRISTOR
REQUIREMENTS
TRIGGERING
The basic approach is to draw the output load line of the firing
circuit onto the gate characteristic curve. It is usually assumed
that the gate drive has a purely resistive linear characterisation
- fig 2. The characteristic is defined by its open circuit source
voltage V
and its short circuit current I
. The straight line
between these 2 points represents the internal source resistance
Fig.2 Output load line for gate drive
Fig.2 Output load line for gate drive
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| AN4853 | Thyristor and diode measurement with a multi-meter |
| AN4870 | The effect of temperature on thyristor performance |
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相關(guān)代理商/技術(shù)參數(shù) |
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| AN4853 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Thyristor and diode measurement with a multi-meter |
| AN486-2 | 制造商:NEW SURPLUS HARDWARE 功能描述: |
| AN4869 | 制造商:DYNEX 制造商全稱:Dynex Semiconductor 功能描述:Power Assemblies |
| AN4870 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:The effect of temperature on thyristor performance |
| AN48800A | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Low current consumption, high sensitivity CMOS Hall IC One-way magnetic field operation |
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