TC2054-2.5VCTTR MICROCHIP [Microchip Technology], TC2054-2.5VCTTR Datasheet - Page 13
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TC2054-2.5VCTTR
Manufacturer Part Number
TC2054-2.5VCTTR
Description
50 mA, 100 mA, and 150 mA CMOS LDOs with Shutdown and Error Output
Manufacturer
MICROCHIP [Microchip Technology]
Datasheet
1.TC2054-2.5VCTTR.pdf
(22 pages)
5.0
5.1
Integrated thermal protection circuitry shuts the
regulator off when the die temperature exceeds
approximately 160°C. The regulator remains off until
the die temperature cools to approximatley 150°C.
5.2
The amount of power the regulator dissipates is
primarily a function of input and output voltage, and
output current.
Equation 5-1
dissipation:
EQUATION 5-1:
The
(Equation
temperature (T
temperature (125 °C) and the thermal resistance from
junction-to-air (θ
a θ
typical two layer FR4 dielectric copper clad PC board.
EQUATION 5-2:
© 2009 Microchip Technology Inc.
Where:
P
V
V
I
LOADMAX
JA
D
INMAX
OUTMIN
of approximately 220°C/Watt when mounted on a
Where all terms are previously defined.
maximum
THERMAL CONSIDERATIONS
Thermal Shutdown
Power Dissipation
P D
5-2) is a function of the maximum ambient
≈
= Worst-case actual power dissipation
= Maximum voltage on V
= Minimum regulator output voltage
= Maximum output (load) current
is used to calculate worst case power
P
(
V
A MAX
DMAX
JA
INMAX
). The 5-Pin SOT-23A package has
allowable
), the maximum allowable die
=
–
T
-------------------------------------- -
V
JMAX
OUTMIN
θ
–
JA
T
power
)I
AMAX
LOADMAX
IN
dissipation
Equation 5-1
Equation 5-2
within limits. For example:
Actual power dissipation:
Maximum allowable power dissipation:
In this example, the TC2054 dissipates a maximum of
only 26.7 mW; far below the allowable limit of 318 mW.
In a similar manner,
be used to calculate maximum current and/or input
voltage limits.
5.3
The primary path of heat conduction out of the package
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 θ
increase the maximum allowable power dissipation
limit.
Given:
Find:
V
V
I
T
1. Actual power dissipation
2. Maximum allowable dissipation
P
LOADMAX
AMAX
D
INMAX
OUTMIN
TC2054/2055/2186
=
Layout Considerations
=
=
(
V
to ensure regulator thermal operation is
26.7mW
[
INMAX
P
(
can be used in conjunction with
3.0 1.1
DMAX
= 3.0V +10%
= 2.7V – 2.5%
= 40 mA
= +55°C
×
Equation 5-1
–
V
=
=
=
OUTMIN
)
T
-------------------------------------- -
318mW
125 55
-------------------- -
–
JMAX
(
220
2.7 0.975
–
θ
)I
×
–
JA
LOADMAX
T
and
AMAX
DS21663D-page 13
JA
Equation 5-2
)
]40 10
and, therefore,
×
3 –
can