A1140LUA Allegro Microsystems Inc, A1140LUA Datasheet - Page 10

• Manufacturer Part Number: A1140LUA
• Description: IC SWITCH HALL EFFECT UNI 3-SIP
• Manufacturer: Allegro Microsystems Inc
• Type: Unipolar Switchr

Specifications of A1140LUA

• Sensing Range: 110G Trip, 45G Release
• Voltage - Supply: 3.5 V ~ 24 V
• Current - Supply: 5mA
• Output Type: Digital, Open Drain
• Features: Regulated Voltage
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 3-SIP
• Magnetic Type: Unipolar
• Operating Supply Voltage (min): 3.5V
• Operating Supply Voltage (typ): 5/9/12/15/18V
• Operating Supply Voltage (max): 24V
• Mag Sensor Operate Point (g): 110Gs
• Mag Sensor Release Point (g): 45Gs
• Mag Sensor Hysteresis(g): 15Gs
• Package Type: Ultra Mini SIP
• Pin Count: 3
• Mounting: Through Hole
• Operating Temp Range: -40C to 150C
• Operating Temperature Classification: Automotive
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output (max): -
• Lead Free Status / Rohs Status: Not Compliant

A1140, A1141,
A1142, and A1143
Power Derating
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
A worst-case estimate, P
able power level (V
at a selected R
A
CC
, and air motion are significant external factors, damped by
ΔT = P
= 12 V, I
T
P
D
J
= T
= V
A
D
CC
+ ΔT = 25°C + 7°C = 32°C
×
CC
θJA
×
R
= 4 mA, and R
I
θJA
and T
CC
ΔT = P
P
T
CC(max)
D
J
= 12 V
= 48 mW
= T
= V
A
D(max)
.
A
D
IN
, I
+ ΔT
×
J(max)
J
CC(max)
×
×
. (Thermal data is also available on
, represents the maximum allow-
R
×
θJA
4 mA = 48 mW
J
I
θJA
θJA
, at P
IN
. Under certain combinations of
140 °C/W = 7°C
. Ambient air temperature,
= 140 °C/W, then:
), without exceeding T
(2)
θJA
D
.
, is a figure of merit sum-
(1)
(3)
A
= 25°C,
Sensitive Two-Wire Chopper-Stabilized
θJC
D
), can
J(max)
, is
,
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
CC(max)
θJA
θJA
CC(max)
P
V
ΔT
D(max)
CC(est)
Unipolar Hall Effect Switches
. If V
= 165°C/W, T
max
= 17 mA.
is reliable under these conditions.
= T
= ΔT
= P
CC(est)
CC(est)
J(max)
D(max)
max
≥ V
to V
J(max)
÷ R
– T
÷ I
CC(max)
θJA
CC(max)
A
CC(max)
= 165°C, V
= 165 °C – 150 °C = 15 °C
= 15°C ÷ 165 °C/W = 91 mW
CC(est)
CC
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
, then operation between V
A
. If V
at T
= 91 mW ÷ 17 mA = 5 V
, the application and device can
and V
A
CC(est)
= 150°C, package UA, using
CC(max)
CC(max)
≤ V
J
= 24 V, and
resulting from internal
CC(max)
requires enhanced
D(max)
CC(est)
, then reli-
CC(est)
. First,
.
and
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