IRU1150CM International Rectifier, IRU1150CM Datasheet - Page 5

• Manufacturer Part Number: IRU1150CM
• Description: IC REG ADJ VLDO 4.0A TO-263-5
• Manufacturer: International Rectifier

Specifications of IRU1150CM

• Regulator Topology: Positive Adjustable
• Voltage - Output: 1.25 ~ 5.5 V
• Voltage - Input: Up to 7V
• Voltage - Dropout (typical): 0.7V @ 4A
• Number Of Regulators: 1
• Current - Output: 4A
• Current - Limit (min): 4.2A
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-5, D²Pak (5 leads + Tab), TO-263BA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: IRU1150-CM; IRU1150-CM

Stability
The IRU1150 requires the use of an output capacitor as
part of the frequency compensation in order to make the
regulator stable. Typical designs for the microprocessor
applications use standard electrolytic capacitors with
typical ESR in the range of 50 to 100mΩ and an output
capacitance of 500 to 1000µF. Fortunately as the ca-
pacitance increases, the ESR decreases resulting in a
fixed RC time constant. The IRU1150 takes advantage
of this phenomena in making the overall regulator loop
stable.
For most applications a minimum of 100µF aluminum
electrolytic capacitor such as Sanyo, MVGX series,
Panasonic FA series as well as the Nichicon PL series
insures both stability and good transient response.
Thermal Design
The IRU1150 incorporates an internal thermal shutdown
that protects the device when the junction temperature
exceeds the allowable maximum junction temperature.
Although this device can operate with junction tempera-
tures in the range of 150 C, it is recommended that the
selected heat sink be chosen such that during maxi-
mum continuous load operation the junction tempera-
ture is kept below this number. The example below
shows the steps in selecting the proper surface mount
package.
www.irf.com
Assuming, the following conditions:
Calculate the maximum power dissipation using the fol-
lowing equation:
Using table below select the proper package and the
amount of copper board needed.
Pkg
TO-263 1.4"X1.4"
TO-263 1.0"X1.0"
TO-263 0.7"X0.7"
TO-263 Pad Size
SO-8
Note: Above table is based on the maximum junction
temperature of 135 C.
As shown in the above table, any of the two packages
will do the job. For low cost applications the SOIC 8-pin
package is recommended.
V
V
V
I
P
P
OUT
OUT
IN
CTRL
D
D
= I
= 2×(3.3 - 2.7)+
= 3.3V
= 2A (DC Avg)
Copper
1.0"X1.0"
= 2.7V
Area
OUT
= 5V
×(V
IN
- V
JA
25
30
35
55
45
( C/W)
OUT
( )
)+
60
2
( )
IRU1150(PbF)
I
60
OUT
×(5 - 2.7) = 1.28W
(
T
Max Pd
A
4.4W
3.7W
3.1W
2.4W
2.0W
=25 C
×(V
CTRL
)
- V
Max Pd
(
T
A
=45 C
3.6W
3.0W
2.6W
1.63W
OUT
2.0W
)
)
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