Allegro A1186LUA-T Ultrasensitive two-wire field-programmable chopper-stabilized unipolar hall-effect switch Datasheet

A1185 and A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall-Effect Switches
Features and Benefits
Description
▪ Chopper stabilization
▫ Low switchpoint drift over operating
temperature range
▫ Low sensitivity to stress
▪ Field programmable for optimized switchpoints
▪ On-chip protection
▫ Supply transient protection
▫ Reverse-battery protection
▫ On-board voltage regulator
▫ 3.5 to 24 V operation
The A1185 and A1186 are ultrasensitive, two-wire, unipolar
Hall effect switches. The operate point, BOP, can be fieldprogrammed, after final packaging of the sensor and
placement into the application. This advanced feature allows
the optimization of the sensor switching performance, by
effectively accounting for variations caused by mounting
tolerances for the device and the target magnet.
Packages: 3 pin SOT23W (suffix LH), and
3 pin SIP (suffix UA)
This family of devices are produced on the Allegro
MicroSystems new DABIC5 BiCMOS wafer fabrication
process, which implements a patented, high-frequency, chopperstabilization technique that achieves magnetic stability and
eliminates the offsets that are inherent in single-element devices
exposed to harsh application environments. Commonly found
in a number of automotive applications, the A1185 and A1186
devices are utilized to sense: seat track position, seat belt buckle
presence, hood/trunk latching, and shift selector position.
Two-wire unipolar switches are particularly advantageous
in price-sensitive applications, because they require one less
wire than the more traditional open-collector output switches.
Continued on the next page…
Not to scale
Functional Block Diagram
V+
VCC
Program/Lock
Programming
Logic
Offset
Adjust
Regulator
Clock/Logic
Amp
Sample and Hold
Dynamic Offset
Cancellation
0.01 uF
Low-Pass
Filter
To all
subcircuits
GND
Package UA Only
A1185-DS, Rev. 2
GND
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
A1185 and
A1186
Description (continued)
Additionally, the system designer gains inherent diagnostics
because output current normally flows in either of two narrowlyspecified ranges. This provides distinct current ranges for IOUT(H)
and IOUT(L). Any output current level outside of these two ranges
is a fault condition.
Other features of the A1185 and A1186 devices include on-chip
transient protection and a Zener clamp on the power supply to protect
against overvoltage conditions on the supply line.
The output current of the A1186 switches HIGH in the presence of
a south polarity magnetic field of sufficient strength; and switches
LOW otherwise, including when there is no significant magnetic field
present. The A1185 has an inverted output current level: switching
LOW in the presence of a south polarity magnetic field of sufficient
strength, and HIGH otherwise.
Both devices are offered in two package styles: LH, a SOT-23W
miniature low-profile package for surface-mount applications, and
UA, a three-lead ultramini Single Inline Package (SIP) for throughhole mounting. Each package is available in a lead (Pb) free version
(suffix, –T) with 100% matte tin plated leadframe.
Factory-programmed versions are also available. Refer to: A1145
and A1146.
Selection Guide
Ambient, TA
(°C)
Pb-free1
Packing2
A1185ELHLT-T
Yes
7-in. reel, 3000 pieces/reel
Surface mount
A1185EUA-T
Yes
Bulk, 500 pieces/bag
4-pin SIP through hole
A1185LLHLT-T
Yes
7-in. reel, 3000 pieces/reel
Surface mount
A1185LUA-T
Yes
Bulk, 500 pieces/bag
4-pin SIP through hole
A1186ELHLT-T
Yes
7-in. reel, 3000 pieces/reel
Surface mount
Part Number
Mounting
A1186EUA-T
Yes
Bulk, 500 pieces/bag
4-pin SIP through hole
A1186LLHLT-T
Yes
7-in. reel, 3000 pieces/reel
Surface mount
A1186LUA-T
Yes
Bulk, 500 pieces/bag
4-pin SIP through hole
Output
South (+) Field3
Supply Current at Low
Output, ICC(L)
(mA)
–40 to 85
Low
–40 to 150
5 to 6.9
–40 to 85
High
–40 to 150
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 device 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: A1185ELHLT,
A1185EUA, A1185LLHLT, A1185LUA, A1186ELHLT, A1186EUA, A1186LLHLT, and A1186LUA.
2Contact Allegro for additional packing options.
3South (+) magnetic fields must be of sufficient strength.
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage
VCC
28
V
Reverse Supply Voltage
VRCC
–18
V
Magnetic Flux Density
B
Unlimited
G
Range E
–40 to 85
ºC
Range L
Operating Ambient Temperature
TA
–40 to 150
ºC
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Storage Temperature
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
ELECTRICAL CHARACTERISTICS over the operating voltage and temperature ranges, unless otherwise specified
Characteristic
Supply
Symbol
Voltage1
Supply Current2
Test Conditions
Min.
Typ.
Max.
Units
3.5
–
24
V
VCC
Device powered on
ICC(L)
B >BOP for A1185; B <BRP for A1186
5
–
6.9
mA
ICC(H)
B >BOP for A1186; B <BRP for A1185
12
–
17
mA
Supply Zener Clamp Voltage
VZSupply
ICC = ICC(L)(Max) + 3 mA; TA = 25°C
28
–
40
V
Supply Zener Clamp Current3
IZSupply
VSupply = 28 V
–
–
9.9
mA
Reverse Supply Current
IRCC
VRCC = –18 V
–
–
1.6
mA
Output Slew Rate4
di/dt
No bypass capacitor; capacitance of the
oscilloscope performing the measurement
= 20 pF
–
36
–
mA/μs
–
200
–
kHz
After factory trimming; with and without
bypass capacitor (CBYP = 0.01 μF)
–
–
25
μs
ton ≤ ton(max); VCC slew rate > 25 mV/μs
–
HIGH
–
–
Chopping Frequency
fC
Power-On Time5
ton
Power-On State6,7
POS
1V
CC represents
2Relative values
the generated voltage between the VCC pin and the GND pin.
of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic
polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present).
3I
ZSUPPLY(max) = ICCL(max) + 3 mA.
4Measured without bypass capacitor between VCC and GND. Use of a bypass capacitor results in slower current change.
5Measured with and without bypass capacitor of 0.01 μF. Adding a larger bypass capacitor causes longer Power-On Time.
6POS is defined as true only with a V
CC slew rate of 25 mV / μs or greater. Operation with a VCC slew rate less than 25 mV / μs can permanently harm
device performance.
7POS is undefined for t > t or B
on
RP < B < BOP .
MAGNETIC CHARACTERISTICS1 over the operating voltage and temperature ranges, unless otherwise specified
Characteristic
Symbol
Programmable Operate Point Range
BOPrange
Test Conditions
Min.
Typ.
Max.
Units
ICC = ICC(L) for A1185
ICC = ICC(H) for A1186
10
–
60
G
Initial Operate Point Range
BOPinit
VCC = 12 V
–
–10
10
G
Switchpoint Step Size2
BRES
VCC = 5 V, TA = 25°C
2
4
6
G
Switchpoint setting
–
5
–
Bit
Programming locking
–
1
–
Bit
–
–
±20
G
5
15
30
G
Number of Programming Bits
–
Temperature Drift of BOP
ΔBOP
Hysteresis
BHYS
BHYS = BOP – BRP
1Relative
values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic
polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present).
2The range of values specified for B
RES is a maximum, derived from the cumulative programming bit errors.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
A1185 and
A1186
Characteristic Data
ICC(H) versus Ambient Temperature
at Various Levels of VCC
(A1185 and A1186)
ICC(L) versus Ambient Temperature
at Various Levels of VCC
(A1185 and A1186)
20
10
18
VCC (V)
6
3.5
12.0
24.0
4
ICC(H) (mA)
ICC(L) (mA)
8
VCC (V)
16
3.5
12.0
24.0
14
12
2
0
10
-50
0
50
100
150
200
-50
0
Ambient Temperature, TA (°C)
100
150
200
Ambient Temperature, TA (°C)
Hysteresis versus Ambient Temperature
at Various Levels of VCC
(A1185 and A1186)
BOP Set by Specific Programming Bit
VCC = 12 V TA = 25°C
(A1185 and A1186)
40
70
60
50
40
30
20
10
0
–10
–20
35
30
BHYS (G)
BOP (G)
50
VCC (V)
25
3.5
12.0
24.0
20
15
10
5
0
1
2
3
4
5
6
-50
0
50
100
150
200
Ambient Temperature, TA (°C)
Bit Number
Device Qualification Program
Contact Allegro for information.
EMC (Electromagnetic Compatibility) Requirements
Contact your local representative for EMC results.
Test Name
Reference Specification
ESD – Human Body Model
AEC-Q100-002
ESD – Machine Model
AEC-Q100-003
Conducted Transients
ISO 7637-2
Direct RF Injection
ISO 11452-7
Bulk Current Injection
ISO 11452-4
TEM Cell
ISO 11452-3
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
RθJA
Package Thermal Resistance
Test Conditions*
Value Units
Package LH, 1-layer PCB with copper limited to solder pads
228
ºC/W
Package LH, 2-layer PCB with 0.463 in.2 of copper area each side
connected by thermal vias
110
ºC/W
Package UA, 1-layer PCB with copper limited to solder pads
165
ºC/W
*Additional thermal information available on Allegro Web site.
Maximum Allowable VCC (V)
Power Derating Curve
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
VCC(max)
2-layer PCB, Package LH
(RθJA = 110 ºC/W)
1-layer PCB, Package UA
(RθJA = 165 ºC/W)
1-layer PCB, Package LH
(RθJA = 228 ºC/W)
20
40
60
80
100
VCC(min)
120
140
160
180
Temperature (ºC)
Power Dissipation, PD (m W)
Power Dissipation versus Ambient Temperature
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
2l
(R aye
rP
θJ
C
A =
11 B, P
0 º ac
1-la
C/ ka
W
(R yer PC
) ge L
θJA =
B
H
165 , Pac
ºC/ kage
W)
UA
1-lay
er P
(R
CB,
θJA =
228 Packag
ºC/W
e LH
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
A1185 and
A1186
Functional Description
Operation
The output, ICC, of the A1185 switches low after the magnetic
field at the Hall sensor exceeds the operate point threshold, BOP.
When the magnetic field is reduced to below the release point
threshold, BRP, the device output goes high. The differences
between the magnetic operate and release point is called the
I+
hysteresis of the device, BHYS. This built-in hysteresis allows
clean switching of the output even in the presence of external
mechanical vibration and electrical noise. The A1186 device
switches with opposite polarity for similar BOP and BRP values,
in comparison to the A1185 (see figure 1).
I+
Switch to High
ICC
ICC
ICC(H)
Switch to Low
Switch to Low
Switch to High
ICC(H)
ICC(L)
BRP
BHYS
(A) A1185
B+
B–
BRP
BOP
B–
ICC(L)
0
BOP
0
B+
BHYS
(B) A1186
Figure 1. Alternative switching behaviors are available in the A118x device family. On the horizontal axis, the B+ direction indicates
increasing south polarity magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the
case of increasing north polarity).
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
Chopper Stabilization Technique
A limiting factor for switchpoint accuracy when using Hall
effect technology is the small signal voltage developed across
the Hall element. This voltage is proportionally small relative to
the offset that can be produced at the output of the Hall sensor
device. This makes it difficult to process the signal and maintain
an accurate, reliable output over the specified temperature and
voltage range.
Chopper stabilization is a unique approach used to minimize
Hall offset on the chip. The Allegro patented technique, dynamic
quadrature offset cancellation, removes key sources of the output
drift induced by temperature and package stress. This offset
reduction technique is based on a signal modulation-demodulation process. The undesired offset signal is separated from the
magnetically induced signal in the frequency domain through
modulation. The subsequent demodulation acts as a modulation
process for the offset causing the magnetically induced signal
to recover its original spectrum at base band while the dc offset
becomes a high frequency signal. Then, using a low-pass filter,
the signal passes while the modulated dc offset is suppressed.
The chopper stabilization technique uses a 200 kHz high frequency clock. For demodulation process, a sample-and-hold
technique is used, where the sampling is performed at twice
the chopper frequency (400KHz). The sampling demodulation
process produces higher accuracy and faster signal processing
capability. Using this chopper stabilization approach, the chip is
desensitized to the effects of temperature and stress. This technique produces devices that have an extremely stable quiescent
Hall output voltage, is immune to thermal stress, and has precise
recoverability after temperature cycling. This technique is made
possible through the use of a BiCMOS process which allows the
use of low-offset and low-noise amplifiers in combination with
high-density logic integration and sample-and-hold circuits.
The repeatability of switching with a magnetic field is slightly
affected using a chopper technique. The Allegro high frequency
chopping approach minimizes the affect of jitter and makes it
imperceptible in most applications. Applications that may notice
the degradation are those that require the precise sensing of alternating magnetic fields such as ring magnet speed sensing. For
those applications, Allegro recommends the “low jitter” family
of digital sensors.
Regulator
Hall Element
Amp
Sample and
Hold
Clock/Logic
Low-Pass
Filter
Figure 2. Chopper stabilization circuit (dynamic quadrature offset cancellation)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
Application Information
For additional general application information, visit the Allegro
Web site at www. allegromicro.com.
are passed directly to the load through CBYP . As a result, the
load ECU (electronic control unit) must have sufficient protection, other than CBYP, installed in parallel with the A118x.
Typical Application and Programming Circuit
The A118x family of devices MUST be protected by an external bypass capacitor, CBYP, connected between the supply pin,
VCC, and the ground pin, GND, of the device. CBYP reduces
both external noise and the noise generated by the chopper-stabilization function. As shown in figure 3, a 0.01 μF capacitor
is typical. (For programming the device, a 0.1 μF capacitor is
recommended for proper fuse blowing.)
A series resistor on the supply side, RS (not shown), in combination with CBYP, creates a filter for EMI pulses.
Installation of CBYP must ensure that the traces that connect
it to the A118x pins are no greater than 5 mm in length. (For
programming the device, the capacitor may be further away from
the device, including mounting on the board used for programming the device.)
CBYP serves only to protect the A118x internal circuitry. All
high-frequency interferences conducted along the supply lines
When determining the minimum VCC requirement of the A118x
device, the voltage drops across RS and the ECU sense resistor,
RSENSE, must be taken into consideration. The typical value for
RSENSE is approximately 100 Ω. (All programming, including
code and lock-bit programming, should be done with direct
connections to VCC and GND, with the use of a 0.1uF bypass
capacitor. Programming across the series resistor or sense resistor may not allow enough energy to properly blow the fuses
in the device, as required for proper programming. The result
would be incorrect switchpoints.
V+
VCC
B
A118x
GND
CBYP
0.01 uF
GND
B
A
A
Package UA Only
B
Maximum separation 5 mm
RSENSE
ECU
Figure 3. Typical application circuit
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
Power Derating
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.)
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)
Example: Reliability for VCC at TA = 150°C, package UA, using
minimum-K PCB.
Observe the worst-case ratings for the device, specifically:
RθJA = 165°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and
ICC(max) = 17 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 ÷ 165 °C/W = 91 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 17 mA = 5 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 mA, and RθJA = 140 °C/W, then:
PD = VCC × ICC = 12 V × 4 mA = 48 mW
ΔT = PD × RθJA = 48 mW × 140 °C/W = 7°C
TJ = TA + ΔT = 25°C + 7°C = 32°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.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
9
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
Programming Protocol
V+
The operate switchpoint, BOP , can be field-programmed. To do
so, a coded series of voltage pulses through the VCC pin is used
to set bitfields in onboard registers. The effect on the device
output can be monitored, and the registers can be cleared and
set repeatedly until the required BOP is achieved. To make the
setting permanent, bitfield-level solid state fuses are blown, and
finally, a device-level fuse is blown, blocking any further coding. It is not necessary to program the release switchpoint, BRP ,
because the difference between BOP and BRP , referred to as the
hysteresis, BHYS , is fixed.
The range of values between BOP(min) and BOP(max) is scaled to
31 increments. The actual change in magnetic flux (G) represented by each increment is indicated by BRES (see the Operating
Characteristics table; however, testing is the only method for
verifying the resulting BOP). For programming, the 31 increments are individually identified using 5 data bits, which are
physically represented by 5 bitfields in the onboard registers.
By setting these bitfields, the corresponding calibration value is
programmed into the device.
Three voltage levels are used in programming the device: a low
voltage, VPL , a minimum required to sustain register settings; a
mid-level voltage, VPM , used to increment the address counter
in the device; and a high voltage, VPH , used to separate sets of
VPM pulses (when short in duration) and to blow fuses (when
long in duration). A fourth voltage level, essentially 0 V, is used
to clear the registers between pulse sequences. The pulse values
are shown in the Programming Protocol Characteristics table and
in figure 4.
VPH
VPM
VPL
Td(P)
0
Td(0)
Td(1)
t
Figure 4. Pulse amplitudes and durations
Additional information on device programming and programming products is available on www. allegromicro.com. Programming hardware is available for purchase, and programming
software is available free of charge.
Code Programming. Each bitfield must be individually set. To
do so, a pulse sequence must be transmitted for each bitfield that
is being set to 1. If more than one bitfield is being set to 1, all
pulse sequences must be sent, one after the other, without allowing VCC to fall to zero (which clears the registers).
The same pulse sequence is used to provisionally set bitfields as
is used to permanently set bitfield-level fuses. The only difference is that when provisionally setting bitfields, no fuse-blowing
pulse is sent at the end of the pulse sequence.
PROGRAMMING PROTOCOL CHARACTERISTICS, over operating temperature range, unless otherwise noted
Characteristic
Symbol
Min.
Typ.
Max.
Units
4.5
5.0
5.5
V
VPM
11.5
12.5
13.5
V
VPH
25
26
27
V
VPL
Programming Voltage1
Programming Current2
Pulse Width
Test Conditions
Minimum voltage range during programming
IPP
tr = 11 μs; 5 V → 26 V; CBYP = 0.1 μF
-
190
-
mA
td(0)
OFF time between programming bits
20
-
-
μs
td(1)
Pulse duration for enable and addressing
sequences
20
-
-
μs
td(P)
Pulse duration for fuse blowing
100
300
-
μs
Pulse Rise Time
tr
VPL to VPM; VPL to VPH
5
-
20
μs
Pulse Fall Time
tf
VPM to VPL; VPH to VPL
5
-
100
μs
1Programming voltages are measured at the VCC pin.
2A bypass capacitor with a minimum capacitance of 0.1
provide the current necessary to blow the fuse.
μF must be connected from VCC to the GND pin of the A118x device in order to
10
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
A1185 and
A1186
The pulse sequences consist of the following groups of pulses:
1. An enable sequence.
2. A bitfield address sequence.
3. When permanently setting the bitfield, a long VPH fuse-blowing pulse. (Note: Blown bit fuses cannot be reset.)
4. When permanently setting the bitfield, the level of VCC must
be allowed to drop to zero between each pulse sequence, in
order to clear all registers. However, when provisionally setting bitfields, VCC must be maintained at VPL between pulse
sequences, in order to maintain the prior bitfield settings while
preparing to set additional bitfields.
Bitfields that are not set are evaluated as zeros. The bitfield-level
fuses for 0 value bitfields are never blown. This prevents inad-
vertently setting the bitfield to 1. Instead, blowing the devicelevel fuse protects the 0 bitfields from being accidentally set in
the future.
When provisionally trying the calibration value, one pulse
sequence is used, using decimal values. The sequence for setting
the value 510 is shown in figure 5.
When permanently setting values, the bitfields must be set individually, and 510 must be programmed as binary 101. Bit 3 is
set to 1 (0001002, which is 410), then bit 1 is set to 1 (0000012,
which is 110). Bit 2 is ignored, and so remains 0.Two pulse
sequences for permanently setting the calibration value 5 are
shown in figure 6. The final VPH pulse is maintained for a longer
period, enough to blow the corresponding bitfield-level fuse.
V+
VPH
VPM
VPL
0
Enable
Address
Try 510
Optional
Monitoring
Clear
t
Figure 5. Pulse sequence to provisionally try calibration value 5.
V+
VPH
VPM
VPL
Address
0
Enable
Address
Encode 001002 (410)
Blow
Enable
Blow
Encode 000012 (110)
Figure 6. Pulse sequence to permanently encode calibration value 5 (101 binary, or
bitfield address 3 and bitfield address 1).
t
11
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
V+
Enabling Addressing Mode. The first segment of code is a
keying sequence used to enable the bitfield addressing mode. As
shown in figure 7, this segment consists of one short VPH pulse,
one VPM pulse, and one short VPH pulse, with no supply interruptions. This sequence is designed to prevent the device from
being programmed accidentally, such as by noise on the supply
line.
VPH
VPM
VPL
0
t
Figure 7. Addressing mode enable pulse sequence
V+
VPH
Address 1
Address 2
Address n ( ≤ 127)
Address Selection. After addressing mode is enabled, the
VPM
target bitfield address, is indicated by a series of VPM pulses, as
shown in figure 8.
VPL
0
t
Figure 8. Pulse sequence to select addresses
V+
Falling edge of final BOP address digit
VPH
Lock Bit Programming. After the desired BOP calibration value
is programmed, and all of the corresponding bitfield-level fuses
are blown, the device-level fuse should be blown. To do so, the
lock bit (bitfield address 32) should be encoded as 1 and have
its fuse blown. This is done in the same manner as permanently
setting the other bitfields, as shown in figure 9.
VPM
VPL
128 pulses
0
Enable
Address
Blow
Encode Lock Bit
Figure 9. Pulse sequence to encode lock bit
t
12
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
A1185 and
A1186
Package LH, 3-Pin (SOT-23W)
3.00 .118
2.70 .106
0.15 [.006] M C A B
3.04 .120
2.80 .110
3
A
A
1.49 .059
NOM
8º
0º
B
B
0.20 .008
0.08 .003
2.10 .083
1.85 .073
A
Preliminary dimensions, for reference only
Dimensions in millimeters
U.S. Customary dimensions (in.) in brackets, for reference only
(reference JEDEC TO-236 AB, except case width and terminal tip-to-tip)
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A Hall element (not to scale)
B Active Area Depth 0.28 [.011]
0.96 .038
0.60 .024
0.25 .010
A NOM
1
2
0.25 .010
3X
SEATING
PLANE
0.10 [.004] C
3X 0.50 .020
0.30 .012
C
SEATING PLANE
GAUGE PLANE
1.17 .046
0.75 .030
0.20 [.008] M C A B
0.15 .006
0.00 .000
0.95 .037
1.90 .075
Pin-out Drawings
Package UA, 3-pin SIP
Package LH, 3-pin SOT
3
1. VCC
2. GND
3. GND
1. VCC
2. No connection
3. GND
NC
1
2
1
2
3
13
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
Package UA, 3-Pin SIP
.164 4.17
.159 4.04
C
D .0805 2.04
.062 1.57
.058 1.47
NOM
.122 3.10
.117 2.97
D
.0565 1.44
NOM D
B
.085 2.16
MAX
.031 0.79
REF
A
.017 0.44
.014 0.35
.640 16.26
.600 15.24
1
2
3
.019 0.48
.014 0.36
.050 1.27
NOM
Dimensions in inches
Metric dimensions (mm) in brackets, for reference only
A Dambar removal protrusion (6X)
B Ejector mark on opposite side
C Active Area Depth .0195 [0.50] NOM
D Hall element (not to scale)
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, 2006 Allegro MicroSystems, Inc.
14
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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