ALLEGRO A1421LK-T

A1421, A1422, A1423
High Precision Hall Effect AC-Coupled Differential Sensor
with Integrated Filter Capacitor
Package K, 4-pin SIP
The A1421, A1422 and A1423 are ac-coupled Hall-effect sensors which include
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 sensor 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 provides 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 frequencies over a wide range of air gaps and temperatures.
1
2
3
4
Each device includes: a voltage regulator, two Hall transducers, temperature compensating 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.
Continued on next page…
1. VCC
2. VOUT
3. TEST
4. GND
ABSOLUTE MAXIMUM RATINGS
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.
A1421a-DS
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
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)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
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 zerocrossing. 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 solutions 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
Part Number
Pb-free1
Output Switching
at BDIFF = 0
Switchpoints
Symmetry
BDiff
Increasing
BDiff
Decreasing
BOP(typ)
(G)
BRP(typ)
(G)
BOP(max)+
BRP(min)
(G)
BOP(typ)+
BRP(typ)
(G)
BOP(min)+
BRP(max)
(G)
A1421LK-T
Yes
Low (On) to
High (Off)
High (Off) to
Low (On)
15
0
15
15
7.5
A1422LK-T
Yes
High (Off) to
Low (On)
Low (On) to
High (Off)
15
–15
0
0
0
A1423LK
A1423LK-T
–
Yes
High (Off) to
Low (On)
Low (On) to
High (Off)
65
–65
0
0
0
Packing2
Bulk, 500
pieces/bag
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
A1421-DS
for additional packing options.
2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
0.1 uF
Hall
Amp
Gain
Stage
VREF
GND
(Pin 4)
(Required)
3
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
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
Symbol
Test Conditions
Min.
Typ.
Max.
Units
4.0
12
26.5
V
–
4.2
7.0
mA
–
140
400
mV
–
–
5
μA
VCC = –18 V
–
–
–1
mA
ELECTRICAL CHARACTERISTICS
Supply Voltage
VCC
Supply Current
ICC
Output Saturation Voltage
Output Leakage Current
Operating; TJ < TJ(max)
VOUT(SAT) ISINK = 20 mA
IOFF
VOUT = 24 V, Bdiff = 0
PROTECTION COMPONENT CHARACTERISTICS
Reverse Supply Current
IRCC
Supply Zener Current
IZSupply
VS = 28 V
–
–
10
mA
Supply Zener Clamp Voltage1
VZSupply
ICC = 10 mA, TA = 25°C
28
33
37
V
Output Zener Current
IZOutput
VOUT = 28 V
–
–
3
mA
Output Zener Clamp Voltage
VZOutput
IOUT = 3 mA, TA = 25°C
28
–
–
V
Output Short Circuit Current Limit
IOUTS(lim)
–
–
50
mA
t < tResponse
–
High
–
V
tPO
VCC > VCC(min)
–
4.5
9
ms
tSettling
fBdiff ≥ 100 Hz
RESPONSE CHARACTERISTICS
Power-On State
Power-On Time2,6
Settling
Time3,6
Response Time6
POS
tResponse Equal to tPO + tSettling; fBdiff ≥ 100 Hz
0
–
50
ms
4.5
–
59
ms
Upper Corner Frequency
fCU
–3 dB, single pole
20
–
–
kHz
Lower Corner Frequency
fCL
–3 dB, single pole
–
–
20
Hz
OUTPUT CHARACTERISTICS
Output Rise Time4
tr
RPU = 1 kΩ, COUTC2 = 10 pF
–
–
200
ns
Output Fall Time
tf
RPU = 1 kΩ, ISINK = 20 mA, COUTC2 = 10 pF
–
–
200
ns
Continued on next page.
4
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
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
0.0
15.0
27.5
G
5.0
15.0
35.0
G
10.0
65.0
100.0
G
-12.5
0.0
7.5
G
-35.0
-15.0
-5.0
G
-100.0
-65.0
-10.0
G
5
15
35
G
MAGNETIC CHARACTERISTICS5,6
Operate Point
Release Point
Hysteresis
Applied Magnetic Field7
1I
CC
BOP
BRP
BHYS
Bdiff
1421, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from low (on) to high (off)
1422, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from high (off) to low (on)
1423, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p
VOUT switches from high (off) to low (on)
1421, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from high (off) to low (on)
1422, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p
VOUT switches from low (on) to high (off)
1423, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p
VOUT switches from low (on) to high (off)
1421, fBdiff = 200 Hz, Bdiff = 50 Gp-p
1422, fBdiff = 200 Hz, Bdiff = 50 Gp-p
–
30
–
G
1423, fBdiff = 200 Hz, Bdiff = 200 Gp-p
–
130
–
G
Differential p-p magnetic field
–
–
1250
G
is equivalent to ICC(max) + 3 mA.
2Time
required to initialize device.
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 B , B , and B
OP
RP
HYS 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.
3Time
5
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
Minimum-K PCB (single-sided with copper limited to solder pads)
177
ºC/W
Package Thermal Resistance
*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
28
VCC(max)
24
22
Power Dissipation, PD (m W)
Maximum Allowable VCC (V)
26
20
18
16
14
Minimum-K PCB
(RθJA = 177 ºC/W)
12
10
8
6
VCC(min)
4
2
0
20
40
60
80
100
120
140
160
180
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
M
(R inim
θJ
20
40
60
A
u
= m-K
17 P
7 C
ºC B
/W
)
80
100
120
Temperature (°C)
140
160
180
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.
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.
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).
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).
Power-On Time, tPO – The time needed by the device, after
power is applied, to initialize all circuitry necessary for proper
operation.
Settling Time, tSettling – The time required by the device, after
tPO, 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.
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.
Response Time, tResponse – The total time required for generating
zero-crossing output transitions after initialization (the sum of
Power-on Time and Settling Time).
6
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
–50
VCC (V)
0
50
100
150
Current (mA)
4.5
12.0
20.0
200
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Over TA Range
TA (ºC)
150
25
–40
0
5
ICC(ON) by TA
ICC(ON) by VCC
Over VCC Range
VCC (V)
4.5
12.0
20.0
0
50
100
150
200
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
TA (ºC)
150
25
–40
0
5
100
150
Voltage (mV)
4.5
12.0
20.0
50
10
15
20
25
VOUT(SAT) by VCC
VCC (V)
0
25
Supply Voltage, VCC (V)
Over VCC Range; ISINK = 20 mA
Ambient Temperature, TA (ºC)
20
Over TA Range
VOUT(SAT) by TA
Voltage (mV)
15
Supply Voltage, VCC (V)
Ambient Temperature, TA (ºC)
500
450
400
350
300
250
200
150
100
50
0
–50
10
Ambient Temperature, TA (ºC)
Current (mA)
Current (mA)
Current (mA)
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
–50
ICC(OFF) by VCC
Over VCC Range
200
500
450
400
350
300
250
200
150
100
50
0
0
Over TA Range; ISINK = 20 mA
TA (ºC)
150
25
–40
5
10
15
20
25
Supply Voltage, VCC (V)
Continued on next page.
7
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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.
8
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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.
9
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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.
10
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
11
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
Reference Specification
ESD – Human Body Model*
AEC-Q100-002
ESD – Machine Model
AEC-Q100-003
Conducted Transients
ISO 7637-1
Direct RF Injection
ISO 11452-7
Bulk Current Injection
ISO 11452-4
TEM Cell
ISO 11452-3
*ESD test is done with no external components.
Vs
R2
C1
1
R1
VCC
4
GND
A1421, A1422
or A1423
VOUT
2
C2
TEST
3
Component
R1*
R2
C1
C2
Value
1
100
0.1
0.1
Units
kΩ
Ω
μF
ηF
*Pull-up resistor not required for
protection but for normal operation.
Recommended EMC test circuit. Test circuit recommended
configuration may change after evaluation of first silicon.
12
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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 differential signal. The hysteresis on each comparator precludes false
switching on noise or target jitter.
The A1421, A1422, and A1423 are versatile high-precision differential 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 switchpoints 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 indeterminate. 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 comparators. One comparator has a positive hysteresis, BHYS1, and
The bandpass filter induces delay in the output signal, VOUT, relative to the applied magnetic field, Bdiff. Simulation data shown
BRP(typ)1421
BHYS1
B OP(typ)1421
Applied Magnetic
Field, Bdiff
A
15.0
0.0
A
BHYS2
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.
13
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
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 output 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 integrated 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.
Power Supply Protection
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.
VS
1
0.1 uF
RPU
VCC
4
A1421, A1422
or A1423
GND
VOUT
VOUT
2
TEST
3
Figure 3. Basic application circuit. A pull-up resistor, RPU, is required
with the output driver.
B OP(typ)1423
65.0
BOP(typ)1421, 1422
Applied Magnetic
Field, Bdiff
15.0
0.0
–15.0
BRP(typ)1421
B RP(typ)1422
–65.0
B RP(typ)1423
1421 Switching State
and Output Signal, VOUT
1422 Switching State
and Output Signal, VOUT
1423 Switching State
and Output Signal, VOUT
Off
On
On
On
Off
Off
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.
14
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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 supplied 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 minimumK PCB
The Package Thermal Resistance, RθJA, is a figure of merit summarizing 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.
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.
PD = VIN × IIN
(1)
ΔT = PD × RθJA
(2)
TJ = TA + ΔT
(3)
Observe the worst-case ratings for the device, specifically:
RθJA = 177°C/W, TJ(max) = 165°C, VCC(max) = 26.5 V, and
ICC(max) = 7.0 mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
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:
PD(max) = ΔTmax ÷ RθJA = 15°C ÷ 177 °C/W = 91 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 7.0 mA = 13 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est).
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced
RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and
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 × ICC = 12 V × 4.2 mA = 50 mW
ΔT = PD × RθJA = 50 mW × 177 °C/W = 9°C
TJ = TA + ΔT = 25°C + 9°C = 34°C
A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max),
at a selected RθJA and TA.
15
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
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
.0592 1.50
NOM
.138 3.51
.133 3.38
C
.063 1.60
.059 1.50
.0507 1.29
NOM
B
E1
E2
A
.045 1.14
MIN
.033 0.84
NOM
.021 0.53
MAX
.085 2.16
MAX
.600 15.24
.560 14.23
.017 0.44
.014 0.35
1
.019
.014
0.48
0.36
2
3
4
.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 Dambar removal protrusion (8X)
B Ejector mark on opposite side
C
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.
16
A1421-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com