Power Derating
Programmable, Chopper-Stabilized,
Two Wire Hall-Effect Switches
A1190, A1192,
and A1193
15
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
The device must be operated below the maximum junction tem-
perature of the device, T
J
(max). Under certain combinations of
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
J
. (Thermal data is also available on the
Allegro MicroSystems Web site.)
The Package Thermal Resistance, R
qJA
, is a figure of merit sum-
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
qJC
, is relatively
small component of R
qJA
. Ambient air temperature, T
A
, and air
motion are significant external factors, damped by overmolding.
The effect of varying power levels (Power Dissipation, P
D
), can
be estimated. The following formulas represent the fundamental
relationships used to estimate T
J
, at P
D
.
P
D
= V
IN
?/DIV>
I
IN
(1)
   DT = P
D
?/DIV>
R
qJA
  (2)
   T
J
= T
A
+ 擳
  (3)
For example, given common conditions such as: T
A
= 25癈,
V
CC
= 12 V, I
CC
= 4 mA, and R
qJA
= 140 癈/W, then:
P
D
= V
CC
?/DIV>
I
CC
= 12 V
?/DIV>
4 mA = 48 mW
DT = P
D
?/DIV>
R
qJA
= 48 mW
?/DIV>
140 癈/W = 7癈
T
J
= T
A
+ DT = 25癈 + 7癈 = 32癈
A worst-case estimate, P
D
(max), represents the maximum allow-
able power level (V
CC
(max), I
CC
(max)), without exceeding
T
J
(max), at a selected R
qJA
and T
A
.
Example: Reliability for V
CC
at T
A
=
150癈, package UA, using a
low-K PCB.
Observe the worst-case ratings for the device, specifically:
R
qJA
=
165 癈/W, T
J
(max)
=
165癈, V
CC
(max)
=
24 V, and
I
CC
(max)
=
17
mA.
Calculate the maximum allowable power level, P
D
(max). First,
invert equation 3:
DT
max
= T
J
(max) T
A
= 165
癈
150
癈 = 15
癈
This provides the allowable increase to T
J
resulting from internal
power dissipation. Then, invert equation 2:
P
D
(max)
= DT
max
?R
qJA
= 15癈 ?165 癈/W = 91 mW
Finally, invert equation 1 with respect to voltage:
V
CC(est)
= P
D
(max)
? I
CC
(max) = 91 mW ?17 mA = 5 V
The result indicates that, at T
A
, the application and device can
dissipate adequate amounts of heat at voltages dV
CC(est)
.
Compare V
CC(est)
to V
CC
(max). If V
CC(est)
d V
CC
(max), then reli-
able operation between V
CC(est)
and V
CC
(max) requires enhanced
R
qJA
. If V
CC(est)
e V
CC
(max), then operation between V
CC(est)
and V
CC
(max) is reliable under these conditions.
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
A1193LUBTN-F-T |
功能描述:2-WIRE FIELD PROGRAMMABLE SWITCH 制造商:allegro microsystems, llc 系列:- 包裝:* 零件狀態(tài):新產(chǎn)品 功能:單極開(kāi)關(guān) 技術(shù):霍爾效應(yīng) 極化:南極 感應(yīng)范圍:1mT Trip, -1mT Release 測(cè)試條件:25°C 電壓 - 電源:3 V ~ 24 V 電流 - 電源(最大值):5mA 電流 - 輸出(最大值):17mA 輸出類(lèi)型:開(kāi)路漏極 特性:可編程跳變點(diǎn) 工作溫度:-40°C ~ 150°C(TA) 封裝/外殼:2-SIP 供應(yīng)商器件封裝:* 標(biāo)準(zhǔn)包裝:1 |
A1193LUBTN-T |
功能描述:2-WIRE FIELD PROGRAMMABLE SWITCH 制造商:allegro microsystems, llc 系列:- 包裝:* 零件狀態(tài):新產(chǎn)品 功能:單極開(kāi)關(guān) 技術(shù):霍爾效應(yīng) 極化:南極 感應(yīng)范圍:1mT Trip, -1mT Release 測(cè)試條件:25°C 電壓 - 電源:3 V ~ 24 V 電流 - 電源(最大值):5mA 電流 - 輸出(最大值):17mA 輸出類(lèi)型:開(kāi)路漏極 特性:可編程跳變點(diǎn) 工作溫度:-40°C ~ 150°C(TA) 封裝/外殼:2-SIP 供應(yīng)商器件封裝:* 標(biāo)準(zhǔn)包裝:1 |
A1194LLHLT-T |
功能描述:IC HALL EFFECT SWITCH SOT-23-3 RoHS:是 類(lèi)別:傳感器,轉(zhuǎn)換器 >> 磁性 - 霍爾效應(yīng),數(shù)字式開(kāi)關(guān),線性,羅盤(pán) (IC) 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 傳感范圍:20mT ~ 80mT 類(lèi)型:旋轉(zhuǎn) 電源電壓:4.5 V ~ 5.5 V 電流 - 電源:15mA 電流 - 輸出(最大):- 輸出類(lèi)型:數(shù)字式,PWM,8.5 位串行 特點(diǎn):可編程 工作溫度:-40°C ~ 150°C 封裝/外殼:20-SSOP(0.209",5.30mm 寬) 供應(yīng)商設(shè)備封裝:20-SSOP 包裝:Digi-Reel® 其它名稱(chēng):AS5132-HSST-500DKR |
A1194LLHLX-T |
功能描述:IC HALL EFFECT SWITCH SOT-23-3 RoHS:是 類(lèi)別:傳感器,轉(zhuǎn)換器 >> 磁性 - 霍爾效應(yīng),數(shù)字式開(kāi)關(guān),線性,羅盤(pán) (IC) 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 傳感范圍:20mT ~ 80mT 類(lèi)型:旋轉(zhuǎn) 電源電壓:4.5 V ~ 5.5 V 電流 - 電源:15mA 電流 - 輸出(最大):- 輸出類(lèi)型:數(shù)字式,PWM,8.5 位串行 特點(diǎn):可編程 工作溫度:-40°C ~ 150°C 封裝/外殼:20-SSOP(0.209",5.30mm 寬) 供應(yīng)商設(shè)備封裝:20-SSOP 包裝:Digi-Reel® 其它名稱(chēng):AS5132-HSST-500DKR |
A1198 |
制造商:SONY 制造商全稱(chēng):Sony Corporation 功能描述:STEREO CASSETTE DECK RECORDING EQUALIZER |
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