TC1014 TelCom Semiconductor, TC1014 Datasheet - Page 4

• Manufacturer Part Number: TC1014
• Description: 50mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS
• Manufacturer: TelCom Semiconductor

is a function of the maximum ambient temperature (T
the maximum allowable die temperature (125 C) and the
thermal resistance from junction-to-air (
SOT-23A-5 package has a
when mounted on a single layer FR4 dielectric copper clad
PC board.
to ensure regulator thermal operation is within limits. For
example:
TC1014-01-6/5/97
TC1014
PRELIMINARY INFORMATION
I
Where:
V
LOAD MAX
V
The maximum allowable power dissipation (Equation 2)
Equation 1 can be used in conjunction with Equation 2
Given:
Find:
Actual power dissipation:
Maximum allowable power dissipation:
OUT MIN
IN MAX
P
Where all terms are previously defined.
D
V
= Worst case actual power dissipation
= Maximum voltage on V
= Minimum regulator output voltage
= Maximum output (load) current
V
P
OUT MIN
1. Actual power dissipation
2. Maximum allowable dissipation
= [(3.0 x 1.1) – (2.7 x .995)]40 x 10
= 18.5mW
P
T
P
IN MAX
D
I
D
LOAD
AMAX
D MAX
(V
(V
P
IN MAX
D MAX
IN MAX
= 3.0V 5%
= 2.7V 0.5V
= 40mA
= 55 C
= (125 – 55)
= 318mW
= (T
J MAX
– V
Equation 1.
Equation 2.
220
= (T
– V
JA
OUT MIN
OUT MIN
J MAX
– T
JA
of approximately 220 C/Watt
A MAX
– T
) I
JA
) I
LOAD MAX
IN
LOAD MAX
)
J MAX )
–3
JA
). The
A MAX
),
4
only 60mW; far below the allowable limit of 318mW. In a
similar manner, Equation 1 and Equation 2 can be used to
calculate maximum current and/or input voltage limits. For
example, the maximum allowable V
the maximum allowable power dissipation of 318mW into
Equation 1, from which V
Layout Considerations
is via the package leads. Therefore, layouts having a
ground plane, wide traces at the pads, and wide power
supply bus lines combine to lower
increase the maximum allowable power dissipation limit.
50mA CMOS LDO WITH SHUTDOWN
In this example, the TC1014 dissipates a maximum of
The primary path of heat conduction out of the package
AND REFERENCE BYPASS
IN MAX
= 5.9V.
IN
is found by sustituting
JA
and, therefore,