RT9726 RICHTEK [Richtek Technology Corporation], RT9726 Datasheet - Page 7

• Manufacturer Part Number: RT9726
• Description: High-Voltage Hysteresis Selectable Temperature Switch
• Manufacturer: RICHTEK [Richtek Technology Corporation]

Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of
IC package, PCB layout, the rate of surroundings airflow
and temperature difference between junction to ambient.
The maximum power dissipation can be calculated by
following formula :
P
Where T
temperature, T
the junction to ambient thermal resistance.
For recommended operating conditions specification of
the RT9726, the maximum junction temperature is 125°C
and T
to ambient thermal resistance θ
For SC-70-6 packages, the thermal resistance θ
/W on the standard JEDEC 51-3 single layer thermal test
board. The maximum power dissipation at T
be calculated by following formula :
P
SC-70-6 package
The maximum power dissipation depends on operating
ambient temperature for fixed T
resistance θ
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
dissipation allowed.
DS9726-01 April 2011
D(MAX)
D(MAX)
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Figure 2. Derating Curves for RT9726 Package
A
is the maximum ambient temperature. The junction
= (T
= (125°C − 25°C) / (333°C / W) = 0.3W for
0
J(MAX)
J(MAX)
JA
. For RT9726 package, the Figure 2 of
A
is the ambient temperature and the θ
is the maximum operation junction
25
− T
Ambient Temperature (°C)
A
) / θ
JA
50
SC-70-6
JA
75
is layout dependent.
J(MAX)
Single Layer PCB
and thermal
A
100
= 25°C can
JA
is 333°C
125
JA
is
Layout Considerations
For best performance of the RT9726, the input capacitor
should be placed as close to the VIN pin and ground plane
as possible to reduce noise coupling.
C
The input capacitor should be
placed as close as possible to
the IC.
IN
Figure 3. PCB Layout Guide
GND
NTC
VIN
2
3
6
5
4
RT9726
EN
REF
OT
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