ATS675LSETN-HT-T Allegro, ATS675LSETN-HT-T Datasheet - Page 12

• Manufacturer Part Number: ATS675LSETN-HT-T
• Manufacturer: Allegro

ATS675LSE
The device must be operated below the maximum junction
temperature of the device, T
peak conditions, reliable operation may require derating supplied
power or improving the heat dissipation properties of the appli-
cation. This section presents a procedure for correlating factors
affecting operating T
Allegro MicroSystems website.)
The Package Thermal Resistance, R
marizing the ability of the application and the device to dissipate
heat from the junction (die), through all paths to the ambient air.
Its primary component is the Effective Thermal Conductivity, K,
of the printed circuit board, including adjacent devices and traces.
Radiation from the die through the device case, R
small component of R
motion are significant external factors, damped by overmolding.
The effect of varying power levels (Power Dissipation, P
be estimated. The following formulas represent the fundamental
relationships used to estimate T
V

A worst-case estimate, P
able power level, without exceeding T
R
For example, given common conditions such as: T
JA
CC
= 12 V, I
and T
A
T = P
.
P
T
CC
D
J
= V
= T
= 7 mA, and R
D
A
CC
J
+ T = 25°C + 6.5°C = 31.5°C
×
. (Thermal data is also available on the
JA
ΔT = P
×
P
T
R
D(max)
D
. Ambient air temperature, T
J
I
JA
CC
= V
= T
J(max)
= 12 V
= 84 mW
A
D
, represents the maximum allow-
IN
JA
J
+ ΔT
× R
, at P
× I
. Under certain combinations of
= 77 °C/W, then:
θJA
JA
IN
×
D
J(max)
.
, is a figure of merit sum-
×
Optimized for Automotive Cam Sensing Applications
7 mA = 84 mW
77 °C/W = 6.5°C
, at a selected
JC
A
= 25°C,
, is relatively
A
, and air
Power Derating
D
), can
(1)
(2)
(3)
Self-Calibrating TPOS Speed Sensor
Example: Reliability for V
Observe the worst-case ratings for the device, specifically:
R
I
Calculate the maximum allowable power level, P
invert equation 3:
This provides the allowable increase to T
power dissipation.
Then, invert equation 2:
P
Finally, invert equation 1 with respect to voltage:
The result indicates that, at T
dissipate adequate amounts of heat at voltages ≤V
Compare V
reliable operation between V
enhanced R
V
CC
JA
CC
V
T(max) = T
(max) = 10 mA.
D
CC
(est) and V
= 101 °C/W, T
(max) = T(max) ÷ R
(est) = P
CC
JA
(est) to V
. If V
D
CC
J
(max) ÷ I
(max) – T
(max) is reliable under these conditions.
J
(max) = 165°C, V
CC
(est) ≥ V
CC
CC
(max). If V
JA
CC
A
115 Northeast Cutoff
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Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
(max) = 148.5 mW ÷ 10 mA = 14.9 V
= 165 °C – 150 °C = 15 °C
A
CC
at T
= 15°C ÷ 101 °C/W = 148.5 mW
, the application and device can
(est) and V
CC
A
(max), then operation between
= 150°C.
CC
CC
(est) ≤ V
(max) = 24 V, and
J
CC
resulting from internal
(max) requires
CC
D
CC
(max). First,
(max), then
(est).
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