A1421_05 [ALLEGRO]
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor; 高精度霍尔效应交流耦合差分传感器集成滤波电容器
| 型号： | A1421_05 |
| 厂家： | 
ALLEGRO MICROSYSTEMS |
| 描述： | High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor |
| 文件： | 总16页 (文件大小：1046K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor
with Integrated Filter Capacitor
The A1421, A1422 and A1423 are ac-coupled Hall-effect sensors which include
Package K, 4-pin SIP
monolithic integrated circuits that switch in response to changing differential
magnetic fields created by rotating ring magnets or, when coupled with a magnet,
by ferrous targets. This family of devices also includes an integrated capacitor that
provides the high accuracy of analog sensing without an external filter capacitor.
This reduces cost and components, while improving the reliability of the final sen-
sor solution.
Magnetic field changes are sensed by two integrated Hall transducers and then
are differentially amplified on the chip. Differential sensing provides immunity to
radial vibration, within the device operating air gap range, by rejection of this
common-mode signal change. Steady-state system offsets are eliminated using an
on-chip differential bandpass filter with integrated capacitor. This filter also pro-
vides relative immunity to interference from electromagnetic sources. The device
utilizes advanced temperature compensation for the high-pass filter, sensitivity,
and Schmitt trigger switchpoints to guarantee optimal operation to low frequen-
cies over a wide range of air gaps and temperatures.
Each device includes: a voltage regulator, two Hall transducers, temperature com-
pensating circuitry, a low-level amplifier, bandpass filter, Schmitt trigger, and an
output driver. The on-board regulator permits operation with supply voltages from
4.0 to 26.5 V. The output stage can switch 20 mA over the full frequency response
range of the sensor, and is compatible with TTL and CMOS logic circuits.
1
2
3
4
Continued on next page…
1. VCC
2. VOUT
3. TEST
4. GND
Features and Benefits
• Integrated tracking capacitor
• Senses motion of ring magnet or ferrous targets
• Wide operating temperature range
• Operation with magnetic input signal frequency from 20 Hz to 30 kHz
• EMI/ESD-resistant
• Large effective air gaps
ABSOLUTE MAXIMUM RATINGS
• 4.0 to 26.5 V supply operating range
• Output compatible with both TTL and CMOS logic families
• Reverse battery protection
• Resistant to mechanical and thermal stress
• Accurate true zero crossing switchpoint (A1421 only)
• High vibration immunity, in running mode (A1423 only)
Supply Voltage, VCC ........................................28 V*
Reverse-Supply Voltage, VRCC ........................–18 V
Output Current, IOUT.......................................25 mA
Reverse-Output Current, IROUT.....................–50 mA
Operating Temperature
Ambient, TA, Range L................–40ºC to 150ºC
Maximum Junction, TJ(max)........................165ºC
Storage Temperature, TS ..................–65ºC to 170ºC
*Refer to Power Derating section.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421a-DS
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
The devices in this family differ from each other in their
switchpoint speci?cations and their switching polarity. The
A1421 has a small hysteresis and asymmetrical switchpoints,
with one switchpoint at the zero-crossing. The A1422 has a small
hysteresis and symmetrical switchpoints, both near the zero-
crossing. The A1423 offers high vibration immunity, by means
of its larger hysteresis that establishes symmetrical switchpoints
further from the zero-crossing. The output polarities are shown
in the Product Selection Guide table.
This variety of options provides ?exibility for achieving solu-
tions for a wide range of applications, including automotive
transmission and crankshaft speed sensing.
The device package has an operating ambient temperature range
–40 °C to 150°C , and is provided in a 4-pin plastic SIP. Each
package is available in a lead (Pb) free version (suffix, –T) , with
a 100% matte tin plated leadframe.
Product Selection Guide
Output Switching
at BDIFF = 0
Switchpoints
Symmetry
BOP(typ) BOP(min)+
1
Part Number Pb-free
Packing2
BOP(max)
BRP(min)
(G)
+
+
BOP(typ)
(G)
BRP(typ)
(G)
BDiff
BDiff
BRP(typ)
(G)
BRP(max)
(G)
Increasing
Decreasing
Low (On) to
High (Off)
High (Off) to
Low (On)
Yes
15
15
65
0
15
0
15
0
7.5
0
A1421LK-T
Bulk, 500
pieces/bag
High (Off) to
Low (On)
Low (On) to
High (Off)
Yes
–15
–65
A1422LK-T
A1423LK
–
High (Off) to
Low (On)
Low (On) to
High (Off)
0
0
0
A1423LK-T
Yes
1Pb-based variants are being phased out of the product line. Certain variants cited in this footnote are in production but have been
determined to be NOT FOR NEW DESIGN. This classification indicates that sale of this device is currently restricted to existing
customer applications. The variants should not be purchased for new design applications because obsolescence in the near future
is probable. Samples are no longer available. Status change: May 1, 2006. These variants include: A1421LK and A1422LK.
2Contact Allegro for additional packing options.
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Functional Block Diagram
VS+
VCC
(Pin 1)
TEST
(Pin 3)
Diagnostic
Circuitry
Regulator
Bandpass Filter Integrated
Tracking Capacitor
Dual Hall
Transducers
VOUT
(Pin 2)
Comparator
Gain
Stage
Hall
Amp
0.1 uF
VREF
GND
(Pin 4)
(Required)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A1421-DS
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
OPERATING CHARACTERISTICS Valid at TA = –40ºC to 150ºC, TJ≤165°C; over operational air gap range and VCC within
operating range, unless otherwise noted. Typical operating parameters: VCC =12 V and TA=25°C.
Characteristic
ELECTRICAL CHARACTERISTICS
Supply Voltage
Symbol
Test Conditions
Min.
Typ.
Max. Units
VCC
ICC
VOUT(SAT) ISINK = 20 mA
IOFF VOUT = 24 V, Bdiff = 0
Operating; TJ < TJ(max)
4.0
–
12
4.2
140
–
26.5
7.0
400
5
V
Supply Current
mA
mV
μA
Output Saturation Voltage
Output Leakage Current
–
–
PROTECTION COMPONENT CHARACTERISTICS
Reverse Supply Current
Supply Zener Current
IRCC
VCC = –18 V
–
–
–
–
–1
10
37
3
mA
mA
V
IZSupply VS = 28 V
Supply Zener Clamp Voltage1
Output Zener Current
VZSupply ICC = 10 mA, TA = 25°C
IZOutput VOUT = 28 V
28
–
33
–
mA
V
Output Zener Clamp Voltage
VZOutput IOUT = 3 mA, TA = 25°C
28
–
–
Output Short Circuit Current Limit
IOUTS(lim)
–
–
50
mA
RESPONSE CHARACTERISTICS
Power-On State
POS
tPO
t < tResponse
–
–
High
4.5
–
9
V
Power-On Time2,6
VCC > VCC(min)
ms
Settling Time3,6
Response Time6
tSettling fBdiff ≥ 100 Hz
0
4.5
20
–
–
–
–
–
50
59
–
ms
ms
kHz
Hz
tResponse Equal to tPO + tSettling; fBdiff ≥ 100 Hz
Upper Corner Frequency
Lower Corner Frequency
fCU
fCL
–3 dB, single pole
–3 dB, single pole
20
OUTPUT CHARACTERISTICS
Output Rise Time4
Output Fall Time
tr
tf
RPU = 1 kΩ, COUTC2 = 10 pF
–
–
–
–
200
200
ns
ns
RPU = 1 kΩ, ISINK = 20 mA, COUTC2 = 10 pF
Continued on next page.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A1421-DS
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
OPERATING CHARACTERISTICS, continued Valid at TA = –40ºC to 150ºC, TJ≤165°C; over operational air gap range and VCC
within operating range, unless otherwise noted. Typical operating parameters: VCC =12 V and TA=25°C.
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max. Units
MAGNETIC CHARACTERISTICS5,6
1421, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from low (on) to high (off)
0.0
5.0
15.0
15.0
27.5
35.0
G
G
G
G
G
G
1422, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
Operate Point
Release Point
BOP
V
OUT switches from high (off) to low (on)
1423, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p
OUT switches from high (off) to low (on)
10.0
-12.5
65.0 100.0
V
1421, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from high (off) to low (on)
0.0
7.5
1422, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from low (on) to high (off)
BRP
-35.0 -15.0
-5.0
1423, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p
VOUT switches from low (on) to high (off)
-100.0 -65.0 -10.0
1421, fBdiff = 200 Hz, Bdiff = 50 Gp-p
1422, fBdiff = 200 Hz, Bdiff = 50 Gp-p
1423, fBdiff = 200 Hz, Bdiff = 200 Gp-p
Differential p-p magnetic field
5
–
–
–
15
30
130
–
35
–
G
G
G
G
Hysteresis
BHYS
Bdiff
–
Applied Magnetic Field7
1250
1ICC is equivalent to ICC(max) + 3 mA.
2Time required to initialize device.
3Time required for the output switchpoints to be within specification.
4Output Rise Time will be dominated by the RC time constant.
5For lower frequencies, the absolute values of BOP, BRP, and BHYS may decrease due to delay induced by the high-pass filter.
6 See Definitions of Terms section.
7 Exceeding the maximum magnetic field may result in compromised absolute accuracy.
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions*
Value
Units
RθJA
Package Thermal Resistance
Minimum-K PCB (single-sided with copper limited to solder pads)
177
ºC/W
*In still air. Additional thermal information available on Allegro Web site.
Maximum Power Dissipation, PD(max)
TJ(max) = 165ºC; VCC = VCC(max); ICC = ICC(max)
Power Derating Curve
TJ(max) = 165ºC; ICC = ICC(max)
30
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
28
V
CC(max)
26
24
22
20
18
16
14
12
10
8
Minimum-K PCB
(RθJA = 177 ºC/W)
6
4
V
CC(min)
2
0
0
20
40
60
80
100
120
140
160
180
20
40
60
80
100
120
140
160
180
Temperature (°C)
Definitions of Terms
The following provide additional information about some of the
parameters cited. For additional information, visit the Allegro
Web site at www.allegromicro.com.
power is applied, to initialize all circuitry necessary for proper
operation.
Settling Time, tSettling – The time required by the device, after
Applied Magnetic Field, Bdiff – The differential magnetic flux
density, which is calculated as the arithmetic difference of the
flux densities observed by each of the two Hall elements. fBdiff is
the input signal frequency.
t
PO, and after a valid magnetic signal has been applied, to
provide proper output transitions. Settling time is a function of
magnetic offset, offset polarity, signal phase, signal frequency,
and signal amplitude.
Output Off Switchpoint (Operate Point), BOP – The value of
increasing differential magnetic flux density at which the device
output switches from low to high (A1421) or high to low (A1422
and A1423).
Supply Current (on), ICC(on) – The current draw of the device
with the output transitor is turned on.
Supply Current (off), ICC(off) – The current draw of the device
with the output transitor is turned off.
Output On Switchpoint (Release Point), BRP – The value of
decreasing differential magnetic flux density at which the device
output switches from high to low (A1421) or from low to high
(A1422 and A1423).
Response Time, tResponse – The total time required for generating
zero-crossing output transitions after initialization (the sum of
Power-on Time and Settling Time).
Power-On Time, tPO – The time needed by the device, after
Allegro MicroSystems, Inc.
6
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Empirical Results
ICC(OFF) by TA
Over VCC Range
ICC(OFF) by VCC
Over TA Range
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
TA (ºC)
VCC (V)
150
25
4.5
12.0
20.0
–40
–50
0
50
100
150
200
0
0
0
5
10
15
20
25
25
25
Ambient Temperature, TA (ºC)
Supply Voltage, VCC (V)
ICC(ON) by TA
Over VCC Range
ICC(ON) by VCC
Over TA Range
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
TA (ºC)
VCC (V)
150
25
4.5
12.0
20.0
–40
–50
0
50
100
150
200
5
10
15
20
Ambient Temperature, TA (ºC)
Supply Voltage, VCC (V)
VOUT(SAT) by TA
Over VCC Range; ISINK = 20 mA
VOUT(SAT) by VCC
Over TA Range; ISINK = 20 mA
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
VCC (V)
TA (ºC)
150
25
4.5
12.0
20.0
–40
0
–50
0
0
50
100
150
200
5
10
15
20
Ambient Temperature, TA (ºC)
Supply Voltage, VCC (V)
Continued on next page.
Allegro MicroSystems, Inc.
7
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Simulation Results
Continued on next page.
Allegro MicroSystems, Inc.
8
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Simulation Results, continued
Continued on next page.
Allegro MicroSystems, Inc.
9
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Simulation Results, continued
Continued on next page.
Allegro MicroSystems, Inc.
10
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Simulation Results, continued
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Sensor Evaluation: EMC Characterization
Please contact Allegro MicroSystems for EMC performance information.
(EMC test results are available after review of first silicon.)
Test Name
ESD – Human Body Model*
Reference Specification
AEC-Q100-002
ESD – Machine Model
Conducted Transients
Direct RF Injection
Bulk Current Injection
TEM Cell
AEC-Q100-003
ISO 7637-1
ISO 11452-7
ISO 11452-4
ISO 11452-3
*
ESD test is done with no external components.
V
s
R2
C1
1
VCC
R1
C2
Component
Value
1
100
0.1
0.1
Units
kΩ
Ω
μF
ηF
A1421, A1422
or A1423
R1*
R2
C1
C2
2
4
GND
VOUT
*
Pull-up resistor not required for
TEST
3
protection but for normal operation.
Recommended EMC test circuit. Test circuit recommended
configuration may change after evaluation of first silicon.
Allegro MicroSystems, Inc.
12
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Applications Information
the other a negative hysteresis, BHYS2. Therefore, one comparator
switches at the BOP crossing on an increasing differential signal
and the other switches at the BRP crossing on a decreasing differ-
ential signal. The hysteresis on each comparator precludes false
switching on noise or target jitter.
The A1421, A1422, and A1423 are versatile high-precision dif-
ferential sensors that can be used in a wide range of applications.
Proper choice of the target material and shape, magnet material
and shape, and assembly techniques enables large working air
gaps and high switchpoint accuracy over the device operating
temperature range.
The behavior is similar for the A1422 and the A1423. The switch-
points are as shown in the magnetic charactersitics table, and the
output polarity is inverted. This is illustrated in figure 2, on the
next page.
Sensor Operation
The device sensor IC contains two integrated Hall transducers
that are used to differentially sense a magnetic field across the
surface of the IC. Referring to figure 1, which shows curves
for the A1421 as an example, the trigger switches the output
when the differential magnetic field crosses the BOP level while
increasing in strength (referred to as the positive direction). In
the example, the A1421 output voltage switches high (off), and
switches the output low (on) when the differential magnetic field
crosses BRP while decreasing (the negative direction).
Start-up
During power-on time, tPO, the output signal, VOUT, is high.
Beyond this time, if the applied magnetic field, Bdiff, is smaller
than BHYS, the switching state and VOUT polarity are indeter-
minate. VOUT will be valid for Bdiff > BHYS, after the additional
settling time, tSettling, has also elapsed.
Delay
The operation is achieved through the use of two separate com-
parators. One comparator has a positive hysteresis, BHYS1, and
The bandpass filter induces delay in the output signal, VOUT, rel-
ative to the applied magnetic field, Bdiff. Simulation data shown
BRP(typ)1421
BOP(typ)1421
BHYS1
A
15.0
Applied Magnetic
Field, Bdiff
0.0
BHYS2
A
Comparator 1, A1421
Comparator 2, A1421
1421 Switching State
Off
Off
On
1421 Output Signal, VOUT
Figure 1. Typical output characteristics with dual comparator operation. The example shown is for the A1421. Characteristics
shown without delay, see characteristic data charts for delay and phase shift contributions.
Allegro MicroSystems, Inc.
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A1421-DS
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www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
in the Characteristic Data section quantify the effect of the input
signal amplitude on the phase shift of the output. Positive values
of delay indicate a lagging output, while negative values indicate
a leading output.
Typical Circuit
A pull-up resistor, RPU, is required between the supply and out-
put terminals, as shown in figure 3. Also, the auxilliary terminal,
TEST, must be connected externally to the GND terminal.
AC-Coupled Operation
Steady-state magnet and system offsets are eliminated using an
on-chip differential bandpass filter. The upper and lower cut-off
frequencies of this patented filter are set using an internal inte-
grated capacitor. The differential structure of this filter improves
the ability of the IC to reject single-ended noise on the GND
or VCC lines and, as a result, makes the device more resistant
to EMI (electromagnetic interference) typically seen in hostile
remote-sensing environments.
VS
1
RPU
VCC
0.1 uF
A1421, A1422
or A1423
VOUT
4
2
Power Supply Protection
GND
VOUT
The device contains an on-chip voltage regulator and can operate
over a wide supply voltage range. In applications that operate the
device from an unregulated power supply, transient protection
must be added externally. For applications using a regulated line,
EMI/RFI protection may still be required. The circuit shown
in figure 3 is the most basic configuration required for proper
device operation.
TEST
3
Figure 3. Basic application circuit. A pull-up resistor, RPU, is required
with the output driver.
BOP(typ)1423
65.0
BOP(typ)1421, 1422
15.0
Applied Magnetic
Field, Bdiff
0.0
–15.0
BRP(typ)1421
BRP(typ)1422
–65.0
BRP(typ)1423
1421 Switching State
and Output Signal, VOUT
Off
On
Off
Off
On
1422 Switching State
and Output Signal, VOUT
On
1423 Switching State
and Output Signal, VOUT
On
Off
On
t+
Figure 2. Comparative typical output characteristics. This chart illustrates the switchpoints and the output polarities of the A1421,
A1422, and the A 1423. Characteristics shown without delay, see characteristic data charts for delay and phase shift contributions.
Allegro MicroSystems, Inc.
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115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Power Derating
Example
The device must be operated below the maximum junction
temperature of the device, TJ(max). Under certain combinations of
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 TJ. (Thermal data is also available on
the Allegro MicroSystems Web site.)
Reliability for VCC at TA=150°C, package L-I1, using minimum-
K PCB
Observe the worst-case ratings for the device, specifically:
RθJA=177°C/W, TJ(max) =165°C, VCC(max)=26.5V, and
ICC(max) = 7.0 mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
The Package Thermal Resistance, RθJA, 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, RθJC, is
relatively small component of RθJA. Ambient air temperature,
TA, and air motion are significant external factors, damped by
overmolding.
ΔTmax = TJ(max) – TA = 165°C–150°C = 15°C
This provides the allowable increase to TJ resulting from internal
power dissipation. Then, invert equation 2:
P
D(max) = ΔTmax ÷RθJA =15°C÷177 °C/W=91mW
Finally, invert equation 1 with respect to voltage:
CC(est) = PD(max) ÷ ICC(max) = 91mW÷7.0mA=13 V
The result indicates that, at TA, the application and device can
V
The effect of varying power levels (Power Dissipation, PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
dissipate adequate amounts of heat at voltages ≤VCC(est)
.
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reli-
able operation between VCC(est) and VCC(max) requires enhanced
RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and
PD = VIN
I
(1)
(2)
(3)
×
IN
ΔT = PD
R
×
θJA
TJ = TA + ΔT
VCC(max) is reliable under these conditions.
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 4.2 mA, and RθJA = 177 °C/W, then:
PD = VCC
I
= 12 V 4.2 mA = 50 mW
×
×
CC
ΔT = PD
R
= 50 mW 177 °C/W = 9°C
×
×
θJA
TJ = TA + ΔT = 25°C + 9°C = 34°C
A worst-case estimate, PD(max), represents the maximum allow-
able power level (VCC(max), ICC(max)), without exceeding TJ(max)
at a selected RθJA and TA.
,
Allegro MicroSystems, Inc.
15
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor with Integrated Filter Capacitor
Package K, 4-pin SIP
.208 5.28
.203 5.16
.0866 2.20
NOM
C
.0592 1.50
NOM
.063 1.60
.059 1.50
.0507 1.29
NOM
B
.138 3.51
.133 3.38
E1
E2
A
.033 0.84
NOM
.045 1.14
MIN
.021 0.53
MAX
.085 2.16
MAX
.600 15.24
.560 14.23
.017 0.44
.014 0.35
1
2
3
4
.019 0.48
.014 0.36
.050 1.27
NOM
Dimensions in inches
Millimeters in brackets, for reference only
Case dimensions exclusive of mold flash or gate burrs
Mold flash .010 [0.25] MAX, gate burr .008 [0.20] MAX, dambar protrusion .004 [0.10] MAX
Exact case and lead configuration at supplier discretion within limits shown
A
B
C
Dambar removal protrusion (8X)
Ejector mark on opposite side
Active Area Depth .0165 [0.42] NOM
The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889;
5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
Copyright © 2004, 2005 Allegro MicroSystems, Inc.
Allegro MicroSystems, Inc.
16
115 Northeast Cutoff, Box 15036
A1421-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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