MC33375, NCV33375 Series
http://onsemi.com
10
THERMAL PROTECTION
Internal thermal limiting circuitry is provided to protect
the integrated circuit in the event that the maximum junction
temperature is exceeded. When activated, typically at
150°C, the output is disabled. There is no hysteresis built
into the thermal protection. As a result the output will appear
to be oscillating during thermal limit. The output will turn
off until the temperature drops below the 150°C then the
output turns on again. The process will repeat if the junction
increases above the threshold. This will continue until the
existing conditions allow the junction to operate below the
temperature threshold.
Thermal limit is not a substitute for proper
heatsinking.
The internal current limit will typically limit current to
450 mA. If during current limit the junction exceeds 150°C,
the thermal protection will protect the device also. Current
limit is not a substitute for proper heatsinking.
OUTPUT NOISE
In many applications it is desirable to reduce the noise
present at the output. Reducing the regulator bandwidth by
increasing the size of the output capacitor will reduce the
noise on the MC33375.
ON/OFF PIN
When this pin is pulled low, the MC33375 is off. This pin
should not be left floating. The pin should be pulled high for
the MC33375 to operate.
Figure 25. SOT−223 Thermal Resistance and Maximum
Power Dissipation versus P.C.B. Copper Length
60
80
100
120
140
160
180
0.4
0.6
0.8
1.0
1.2
1.4
1.6
010203025155.0
L, LENGTH OF COPPER (mm)
P
D(max)
for T
A
= 50°C
R
JA
, THERMAL RESISTANCE,
JUNCTION−TO−AIR (°CW)
P
D
, MAXIMUM POWER DISSIPATION (W)
Minimum
Size Pad
R
JA
L
L
2.0 oz. Copper
Figure 26. SOP−8 Thermal Resistance and Maximum
Power Dissipation versus P.C.B. Copper Length
R , THERMAL RESISTANCE,
JAθ
JUNCTION‐TO‐AIR ( C/W)°
30
50
70
90
110
170
0.4
0.8
1.2
1.6
3.2
02040503010
L, LENGTH OF COPPER (mm)
P
D(max)
for T
A
= 50°C
L
L
R
JA
130
2.0
150
2.4
2.8
Graph Represents Symmetrical Layout
2.0 oz.
Copper
3.0
mm
