ATS616LSG Allegro MicroSystems, ATS616LSG Datasheet - Page 12

• Manufacturer Part Number: ATS616LSG
• Description: Dynamic Self-Calibrating Peak-Detecting Differential Hall Effect Gear Tooth Sensor
• Manufacturer: Allegro MicroSystems

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The device must be operated below the maximum junction
temperature of the device, T
peak conditions, reliable operation may require derating sup-
plied power or improving the heat dissipation properties of the
application. This section presents a procedure for correlating
factors affecting operating T
the Allegro MicroSystems Web site.)
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
relatively small component of R
T
overmolding.
The effect of varying power levels (Power Dissipation, P
be estimated. The following formulas represent the fundamental
relationships used to estimate T
For example, given common conditions such as: T
V
ATS616LSG-DS, Rev. 1
A
CC
, and air motion are significant external factors, damped by
Dynamic Self-Calibrating Peak-Detecting Differential Hall Effect Gear Tooth Sensor
ΔT = P
= 12 V, I
T
P
D
J
= T
= V
A
D
CC
+ ΔT = 25°C + 7°C = 32°C
×
CC
×
R
= 4 mA, and R
I
θJA
CC
ΔT = P
P
T
D
J
= 12 V
= 48 mW
= T
= V
A
D
IN
+ ΔT
×
J(max)
J
×
×
. (Thermal data is also available on
R
×
4 mA = 48 mW
I
θJA
J
θJA
θJA
, at P
IN
. Under certain combinations of
140°C/W = 7°C
. Ambient air temperature,
= 140°C/W, then:
θJA
D
.
, is a figure of merit sum-
(1)
(2)
(3)
A
= 25°C,
ATS616LSG
Power Derating
θJC
D
), can
, is
A worst-case estimate, P
able power level (V
at a selected R
Example: Reliability for V
minimum-K PCB.
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:
Finally, invert equation 1 with respect to voltage:
The result indicates that, at T
dissipate adequate amounts of heat at voltages ≤V
Compare V
able operation between V
R
V
This value applies only to the voltage drop across the ATS616
chip. If a protective series diode or resistor is used, the effec-
tive maximum supply voltage is increased. For example, when a
standard diode with a 0.7 V drop is used:
CC(max)
θJA
θJA
CC(max)
P
V
ΔT
D(max)
CC(est)
. If V
= 126°C/W, T
max
= 12 mA.
V
is reliable under these conditions.
= T
= ΔT
= P
CC(est)
CC(max)
CC(est)
J(max)
D(max)
θJA
max
≥ V
and T
to V
= 9.9 V + 0.7 V = 10.6 V
J(max)
÷ R
– T
CC(max)
÷ I
CC(max)
θJA
CC(max)
A
CC(max)
A
= 165°C, V
= 165 °C – 150 °C = 15 °C
D(max)
.
= 15°C ÷ 126°C/W = 119 mW
CC(est)
CC
, I
, then operation between V
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115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
CC(max)
A
. If V
at T
= 119 mW ÷ 12 mA = 9.92 V
, the application and device can
, represents the maximum allow-
and V
A
CC(est)
= 150°C, package SG, using
CC(max)
), without exceeding T
CC(max)
≤ V
J
= 24 V, and
resulting from internal
CC(max)
requires enhanced
D(max)
CC(est)
, then reli-
CC(est)
. First,
.
J(max)
and
12
,