UGQ5140K データシートの表示（PDF） - Allegro MicroSystems
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UGQ5140K Datasheet PDF : 8 Pages
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5140
PROTECTED POWERHALL®
SENSOR:
LAMP/SOLENOID DRIVER
This stress, unless protected against (as in the
UGQ5140K), will cause the device junction tempera-
ture to rise until it fails catastrophically.
Thermal stress protection is provided in two
manners; delta temperature protection, and junction
temperature protection. Under worst-case conditions
(see Figures 1 and 2), if the output is shorted to
supply, the output transistor will heat up much faster
than the rest of the integrated circuit. This condition
could cause localized failure in the output transistor.
To prevent damage, a delta temperature limiting
scheme is used. If a large thermal gradient is sensed
across the device, the output transistor base drive is
reduced to lower the output current. This reduces the
power (heat) generated by the output transistor.
When thermal stresses cause the junction tem-
perature to reach approximately +165°C, a linear
thermal limiting circuit is activated. This circuit linearly
reduces the base drive of the output transistor to
maintain a constant junction temperature of 165°C. In
this mode, the output current will be a function of the
heat dissipating characteristics of the package and its
environment. Linear thermal limiting eliminates the
low-frequency thermal oscillation problems experi-
enced by thermal shutdown (ON-OFF) schemes.
The output characteristics are shown in Figures 1
and 2. Note the three distinct operating regions: peak
limit, delta limit, and thermal limit. In practice the
output voltage and current may exhibit some oscilla-
tions during peak current limiting due to output load
characteristics. These oscillations are of very-short
duration (typically 50 ms) and may be damped with an
external capacitor between pins 2 and 4.
When the fault condition that caused the output
overload is corrected, the device returns to normal
operating mode.
FIGURE 1
OUTPUT CURRENT UNDER SHORT-CIRCUIT
CONDITIONS
NOT TO SCALE
PEAK CURRENT LIMIT
DELTA TEMP.
LIMIT
JUNCTION
TEMP. LIMIT
TIME
Dwg. WH-002
FIGURE 2
OUTPUT VOLTAGE vs OUTPUT CURRENT
TJ < 150°C
NOT TO SCALE
T = 165°C
J
JUNCTION
TEMP. LIMIT
DELTA
TEMP. LIMIT
V OUT(SAT)
OUTPUT CURRENT, I OUT
Dwg. GP-013-1
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