MIC5239-1.8YS TR Micrel Inc, MIC5239-1.8YS TR Datasheet - Page 11

• Manufacturer Part Number: MIC5239-1.8YS TR
• Description: High Vin, Low Iq Regulator ( )
• Manufacturer: Micrel Inc

Specifications of MIC5239-1.8YS TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.8V
• Voltage - Input: 2.3 ~ 30 V
• Voltage - Dropout (typical): 0.35V @ 500mA
• Number Of Regulators: 1
• Current - Output: 500mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-223 (3 leads + Tab), SC-73, TO-261
• Voltage Regulator Type: Linear
• Topology: LDO
• Regulator Output Type: Fixed
• Polarity Type: Positive
• Number Of Outputs: Single
• Input Voltage (min): 2.3V
• Input Voltage (max): 30V
• Output Voltage: 1.8V
• Package Type: SOT-223
• Output Current: 500mA
• Load Regulation: 30mV
• Line Regulation: 0.5%
• Output Voltage Accuracy: ±1%
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Dropout Voltage@current (max): 0.35@150uA
• Dropout Voltage@current (typ): 0.05@100uA
• Pin Count: 3 +Tab
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Compliant
• Other names: MIC5239-1.8YSTR; MIC5239-1.8YSTR

For example, the maximum ambient temperature is
50°C, the ∆T is determined as follows:
Using Figure 6, the minimum amount of required copper
can be determined based on the required power
dissipation. Power dissipation in a linear regulator is
calculated as follows:
If we use a 3V output device and a 28V input at
moderate output current of 25mA, then our power
dissipation is as follows:
From Figure 6, the minimum amount of copper required
to operate this application at a ∆T of 75°C is 110mm
Quick Method
Determine the power dissipation requirements for the
design along with the maximum ambient temperature at
which the device will be operated. Refer to Figure 7,
which shows safe operating curves for three different
ambient temperatures: 25°C, 50°C and 85°C. From
these curves, the minimum amount of copper can be
determined by knowing the maximum power dissipation
required. If the maximum ambient temperature is 50°C
and the power dissipation is as above, 639mW, the
curve in Figure 7 shows that the required area of copper
is 110mm
The θ
depending upon the availability of copper ground plane
to which it is attached.
Micrel
December 2007
∆T = T
T
T
∆T = 125°C – 50°C
∆T = 75°C
P
P
P
P
J
A
D
D
D
D
JA
(max) = 125°C
(max) = maximum ambient operating
= (V
= (28V – 3V) × 25mA + 28V 250µA
= 625mW + 7mW
= 632mW
of this package is ideally 80°C/W, but it will vary
Figure 7. Copper Area vs. Power-MSOP
2
.
J
IN
(max) – T
– V
temperature
OUT
Power Dissipation (T
) I
A
OUT
(max)
+ V
IN
×  I
GND
A
)
2
.
11
The same method of determining the heatsink area used
for the power MSOP-8 can be applied directly to the
power SOIC-8. The same two curves showing power
dissipation versus copper area are reproduced for the
power SOIC-8 and they can be applied identically.
Power SOIC-8 Thermal Characteristics
The power SOIC-8 package follows the same idea as
the power MSOP-8 package, using four ground leads
with the die attach paddle to create a single-piece
electrical and thermal conductor, reducing thermal
resistance and increasing power dissipation capability.
Quick Method
Determine the power dissipation requirements for the
design along with the maximum ambient temperature at
which the device will be operated. Refer to Figure 9,
which shows safe operating curves for three different
ambient temperatures, 25°C, 50°C, and 85°C. From
these curves, the minimum amount of copper can be
determined by knowing the maximum power dissipation
required. If the maximum ambient temperature is 50°C,
and the power dissipation is 632mW, the curve in Figure
9 shows that the required area of copper is less than
100mm
2
, when using the power SOIC-8.
Figure 8. Copper Area vs. Power-SOIC
Figure 9. Copper Area vs. Power-SOIC
Power Dissipation (∆T
Power Dissipation (T
A
JA
)
)
M9999-121007
MIC5239