MSK5826RH M. S Kennedy, MSK5826RH Datasheet - Page 4

• Manufacturer Part Number: MSK5826RH
• Description: Rad Hard Ultra Low Dropout Positive Adjustable Linear Regulator
• Manufacturer: M. S Kennedy

ing formula for convective heat flow may be used.
Governing Equation:
Where
perature. The absolute maximum allowable junction tem-
perature is 150°C. The equation may now be rearranged
to solve for the required heat sink to ambient thermal
resistance (R
Example:
V
bient temperature is +25°C. The maximum desired junc-
tion temperature is +125°C.
R
greases
Solve for R
of no more than 12.9°C/W must be used to maintain a
junction temperature of no more than 125°C.
THERMAL LIMITING
down temperature of approximately 150°C. This ther-
mal shutdown can be used as a protection feature, but
for continuous operation, the junction temperature of the
pass transistor must be maintained below 150°C. Proper
heat sink selection is essential to maintain these condi-
tions. Exceeding the thermal limit activates the latch fea-
ture of the MSK 5826RH. Toggle the shutdown pin high
then low or cycle power to reset the latch. See shut-
down pin description and overcurrent latch description
for more information.
HEAT SINK SELECTION
OUT
To select a heat sink for the MSK 5826RH, the follow-
The MSK 5826RH control circuitry has a thermal shut-
JC
In this example, a heat sink with a thermal resistance
Next, the user must select a maximum junction tem-
APPLICATION NOTES CONT.
An MSK 5826RH is connected for V
T
P
R
R
R
T
=6.5°C/W and R
R
=+3.3V. I
J
D
A
JC
CS
SA
SA
Power Dissipation=(5.0V-3.3V) x (3A)
T
=
= 12.9°C/W
Power Dissipation=(V
J
= Junction Temperature
= Total Power Dissipation
= Junction to Case Thermal Resistance
= Case to Heat Sink Thermal Resistance
= Heat Sink to Ambient Thermal Resistance
= Ambient Temperature
SA:
=
125°C - 25°C
SA
P
).
D
OUT
X (R
5.1W
is a continuous 3A DC level. The am-
CS
JC
=0.15°C/W for most thermal
+ R
=5.1 Watts
- 6.5°C/W - 0.15°C/W
CS
IN
+ R
-V
OUT
SA
) x I
) + T
IN
=+5.0V and
OUT
A
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4
TYPICAL APPLICATIONS CIRCUIT
TOTAL DOSE RADIATION TEST
PERFORMANCE
generated for all radiation testing performed by MS
Kennedy. These curves show performance trends
throughout the TID test process and are located in the
MSK 5826RH radiation test report. The complete radia-
tion test report is available in the RAD HARD PROD-
UCTS section on the MSK website.
Radiation performance curves for TID testing have been
FIGURE 2
Rev. A 1/09