MIC5249-2.5YMM TR Micrel Inc, MIC5249-2.5YMM TR Datasheet - Page 6

• Manufacturer Part Number: MIC5249-2.5YMM TR
• Description: 300mA UCapl LDO With Reset( )
• Manufacturer: Micrel Inc

Specifications of MIC5249-2.5YMM TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 2.5V
• Voltage - Input: Up to 6V
• Voltage - Dropout (typical): 0.34V @ 300mA
• Number Of Regulators: 1
• Current - Output: 300mA
• Current - Limit (min): 300mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MIC5249-2.5YMMTR; MIC5249-2.5YMMTR

Thermal Consideration
The MIC5249 is designed to provide 300mA of
continuous current in a very small package. Maximum
power dissipation can be calculated based on the output
current and the voltage drop across the device. To
determine the maximum power dissipation of the
package, use the junction-to-ambient thermal resistance
of the device and the following basic equation:
T
125°C and T
is layout dependent; Table 1 shows examples of the
junction-to-ambient thermal resistance for the MIC5249.
The actual power dissipation of the regulator circuit can
be determined using the equation:
Substituting P
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit.
For example, when operating the MIC5249-3.0BMM at
Micrel, Inc.
September 2006
J(max)
is the maximum junction temperature of the die,
P
P
Package
D
D(max)
MSOP-8
Table 1. MSOP-8 Thermal Resistance
= (V
A
D(max)
is the ambient operating temperature. θ
IN
=
– V
⎛
⎜
⎜
⎝
T
for P
J(max)
OUT
θ
JA
) I
D
−
OUT
and solving for the operating
T
A
+ V
⎞
⎟
⎟
⎠
θJA Recommended
Minimum Footprint
IN
I
GND
200°C/W
JA
6
50°C with a minimum footprint layout, the maximum
input voltage for a set output current can be determined
as follows:
The junction-to-ambient thermal resistance for the
minimum footprint is 200°C/W, from Table 1. The
maximum power dissipation must not be exceeded for
proper operation. Using the output voltage of 3.0V, and
an output current of 300mA, the maximum input voltage
can be determined. Because this device is CMOS and
the ground current is typically 90µA over the load range,
the power dissipation contributed by the ground current
is < 1.0% and can be ignored for this calculation.
Therefore, a 3.0V application at 300mA of output current
can accept a maximum input voltage of 4.25V in the
MSOP-8 package. For a full discussion of heat sinking
and thermal effects on the voltage regulators, refer to the
“Regulator Thermals” section of Micrel’s Designing with
Low-Dropout Voltage Regulators Handbook .
375mW = (V
375mW = V
1275mW = V
V
P
IN(max)
D(max)
= 4.25V
=
⎛
⎜
⎝
125
IN
IN
200
IN
× 300mA – 900mW
°
– 3.0V) 300mA
× 300mA
C
°
−
C/W
50
°
C
⎞
⎟
⎠
M9999-090806
MIC5249