A3054: Multiplexed Two-Wire Hall-Effect Sensor IC ICs

Data Sheet
27680.1*
3054
MULTIPLEXED TWO-WIRE
HALL-EFFECT SENSOR ICs
The A3054KU and A3054SU Hall-effect sensor ICs are digital magnetic sensing ICs capable of communicating over a two-wire power/
signal bus. Using a sequential addressing scheme, the device responds to a signal on the bus and returns the diagnostic status of the
IC, as well as the status of each monitored external magnetic field.
As many as 30 devices can function on the same two-wire bus. This
IC is ideal for multiple sensor applications where minimizing the wiring
harness size is desirable or essential.
X
LOGIC
1
2
3
BUS
GROUND
SWITCH IN
T
C
.
y
U
l
D
n
O
o
R
e
P nc
D
e
r
E
e
U
f
N re
I
T
r
N
o
f
O
n
C
S ow
I
D h
S
—
Dwg. PH-005
Pinning is shown viewed from branded side.
Each device consists of high-resolution bipolar Hall-effect switching circuitry, the output of which drives high-density CMOS logic
stages. The logic stages decode the address pulse and enable a
response at the appropriate address. The combination of magneticfield or switch-status sensing, low-noise amplification of the Halltransducer output, and high-density decoding and control logic is made
possible by the development of a new IC DABiC™ (digital analog
bipolar CMOS) fabrication technology. The A3054SU is an improved
replacement for the original UGN3055U.
These unique magnetic sensing ICs are available in two temperature ranges; the A3054SU operates within specifications between
-20°C and +85°C, while the A3054KU is rated for operation between
-40°C and +125°C. Alternative magnetic and temperature specifications are available on special order. Both versions are supplied in
0.060" (1.54 mm) thick, three-pin plastic SIPs. Each device is clearly
marked with a two-digit device address (XX).
FEATURES
■
■
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Supply Voltage, VBUS . . . . . . . . . . . . . . 18 V
Magnetic Flux Density, B . . . . . . . Unlimited
■
■
■
■
Complete Multiplexed Hall-Effect ICs with
Simple Sequential Addressing Protocol
Allows Power and Communication Over a
Two-Wire Bus (Supply/Signal and Ground)
Up to 30 Hall-Effect Devices Can Share a Bus
Diagnostic Capabilities
Magnetic-Field or Switch-Status Sensing Applications
Low Power of DABiC Technology Favors
Battery-Powered and Mobile Applications
Ideal for Automotive, Consumer, and Industrial Applications
Operating Temperature Range, T A
A3054KU . . . . . . . . . . -40°C to +125°C
■
A3054SU . . . . . . . . . . . . -20°C to +85°C
Storage Temperature Range,
Always order by complete part number:
TS . . . . . . . . . . . . . . . . -55°C to +150°C
Package Power Dissipation,
PD . . . . . . . . . . . . . . . . . . . . . . . 635 mW
Part Number
Operating Temperature Range
A3054KU-XX
-40°C to +125°C
A3054SU-XX
-20°C to +85°C
where XX = address (01, 02, … 29, 30).
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
ELECTRICAL CHARACTERISTICS over operating temperature range.
Limits
Characteristic
Power Supply Voltage
Symbol
Test Conditions
VBUS
Min
Typ
Max
Units
—
—
15
V
Signal Current
IS
DUT Addressed, B > 300 G
12
15
20
mA
Quiescent Current
IQL
VBUS = 6 V
—
1.5
2.5
mA
IQH
VBUS = 9 V
—
1.4
2.5
mA
∆IQ
IQL – IQH
—
100
300
µA
Address Range
Addr
Factory Specified
1
—
30
—
Clock Thresholds
VCLH
LOW to HIGH
—
—
8.5
V
VCHL
HIGH to LOW
6.5
—
—
V
VCHYS
Hysteresis
—
0.8
—
V
50% Duty Cycle
2.5
—
—
kHz
Max. Clock Frequency*
fCLK
Address LOW Voltage
VL
VRST
6.0
VCHL
V
Address HIGH Voltage
VH
VCLH
9.0
VBUS
V
VRST
2.5
3.5
5.5
V
Reset Voltage
Propagation Delay*
Pin 3-2 Resistance
Pin 3-2 Output Voltage
tplh
LOW to HIGH
10
20
30
µs
tphl
HIGH to LOW
—
5.0
10
µs
RSWH
DUT Addressed, B < 5 G
—
50
—
kΩ
RSWL
DUT Addressed, B > 300 G
—
200
—
Ω
VSWH
DUT Addressed, B < 5 G
—
3.9
—
V
VSWL
DUT Addressed, B> 300 G
—
30
—
mV
MAGNETIC CHARACTERISTICS over operating temperature range.
Limits
Characteristic
Magnetic Threshold†
Hysteresis
Symbol
Test Conditions
Min.
Typ.
Max.
Units
BOP
Turn-On
50
150
300
G
BRP
Turn-Off
5.0
100
295
G
BHYS
BOP – BRP
5.0
50
—
G
Typical Data is at TA = +25°C and is for design information only.
*This parameter, although warranteed, is not production tested.
†Alternative magnetic switch point specifications are available on special order. Please contact the factory.
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 2001 Allegro MicroSystems, Inc.
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
ELEMENT LOCATION
(±0.005” [0.13 mm] die placement)
ACTIVE AREA DEPTH
0.0165"
0.42 mm
NOM
FUNCTIONAL BLOCK DIAGRAM
1
BUS
0.090"
2.29 mm
REG
0.073"
1.85 mm
COMP
CLOCK
COMP
CMOS LOGIC
RESET
A
BRANDED
SURFACE
3
1
2
SWITCH IN
(OPTIONAL)
3
2
GROUND
Dwg. FH-009
Dwg. MH-002-10B
DEFINITION OF TERMS
Device Address
Each bus device has a factory-specified predefined
address. At present, allowable device addresses are
integers from 01 to 30.
LOW-to-HlGH Clock Threshold (VCLH)
Minimum voltage required during the positive-going
transition to increment the bus address and trigger a
diagnostic response from the bus devices. This is also
the maximum threshold of the on-chip comparator that
monitors the supply voltage, VBUS.
HlGH-to-LOW Threshold (VHL)
Maximum voltage required during the negative-going
transition to trigger a signal current response from the bus
devices. This is also the maximum threshold of the
on-chip comparator that monitors the supply voltage,
VBUS.
Bus HIGH Voltage (VH)
Bus HIGH voltage during addressing. Voltage should
be greater than VCLH.
Address LOW Voltage (VL)
Bus LOW voltage during addressing. Voltage should
be greater than VRST and less than VCHL.
Bus Reset Voltage (VRST)
Voltage level while resetting devices.
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Devuce Quiescent Current Drain (IQ)
The current drain of bus devices when active but not
addressed. IQH is the quiescent current drain when the
device is not addressed and is at V H IQL is the quiescent
current drain when the device is not addressed and is at
VL. Note that IQL is greater than IQH.
Diagnostic Phase
Period on the bus when the address voltage is at V H.
During this period, a correctly addressed device responds
by increasing its current drain on the bus. This response
from the device is called the diagnostic response and
the bus current increase is called the diagnostic current.
Signal Phase
Period on the bus when the address voltage is at V L.
During this period, a correctly addressed device that
detects a magnetic field greater than the magnetic operate point, BOP, responds by maintaining a current drain of
IS on the bus. This response from the device is called the
signal response and the bus current is called the signal
current.
Device Address Response Current (I S)
Device current during the diagnostic and the signal
responses of the bus device. This is accomplished by
enabling an internal constant-current source.
Allegro
3
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
ADDRESSING PROTOCOL
Magnetic Operate Point (BOP)
Minimum magnetic field required to switch ON the
Hall amplifier and switching circuitry of the addressed
device. This circuitry is only active when the device is
addressed.
Magnetic Release Point (BRP)
Magnetic field required to switch OFF the Hall
amplifier and switching circuitry after the output has been
switched ON. When a device is deactivated by changing
the bus address, all magnetic memory is lost.
Magnetic Hysteresis (BHYS)
Difference between the BOP and BRP magnetic field
thresholds.
A device may be addressed by changing the supply
voltage as shown in Figure 1. A preferred addressing
protocol is as follows: the bus supply voltage is brought
low (<2.5 V) so that all devices on the bus are reset. The
voltage is then raised to the address LOW voltage (V L) and
the bus quiescent current is measured. The bus is then
toggled between VL and VH (address HIGH voltage), with
each positive transition representing an increment in the
bus address. After each voltage transition, the bus current
may be monitored to check for diagnostic and signal
responses from sensor ICs.
Device Addressing
When a device detects a bus address equal to its
factory-programmed address, it responds with an increase
in its supply current drain ( I S) during the next HIGH portion
FIGURE 1
BUS TIMING
DIAGNOSTIC
ADDRESS 01
V
V
BUS
VOLTAGE
DIAGNOSTIC
ADDRESS 03
DIAGNOSTIC
ADDRESS 04
DIAGNOSTIC
ADDRESS n
DIAGNOSTIC
ADDRESS 01
CLH
V
CHL
V
L
V
RESET
RESET
RST
t plh
0
t phl
DEVICE 02 —
DIAGNOSTIC CURRENT
IS
DEVICE 02
CURRENT
WITH NO
MAGNETIC
FIELD
DIAGNOSTIC
ADDRESS 02
H
I QL
I QH
0
I
DEVICE 03
CURRENT
WITH
MAGNETIC
FIELD
DEVICE 03 — DIAGNOSTIC
AND SIGNAL CURRENTS
S
I QL
I QH
0
I
TOTAL
BUS CURRENT
WITH
MAGNETIC
FIELD AT
DEVICE 03
S
DEVICE 01
NOT PRESENT
DEVICE 01
NOT PRESENT
n • I QL
n • IQH
0
Dwg. WH-005
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
Bus Current
Figure 1 shows the addressing protocol.
The top trace represents the bus voltage
transitions as controlled by the bus driver
(see Applications Notes for an optimal bus
driver schematic). The second trace represents the bus current contribution of Device
02. The diagnostic response from the device
indicates that it detected its address on the
bus. However, no signal current is shown,
which indicates that sufficient magnetic field
is not detected at the chip surface and that
pin 3 is open circuited. The third trace
represents the current drain of Device 03
when a magnetic field is detected. Note both
the diagnostic and signal currents from the
device. The last trace represents the overall
bus current drain. When no devices are
addressed, the net bus current is the sum of
quiescent currents of all devices on the bus
(for 'n' devices, the bus current drain is
n • IQ).
Bus Issues
After a reset, while at the address LOW
voltage (VL), and before the first address
pulse, bus current calibration may be performed. This feature allows for fail-safe
detection of signal current and eliminates
detection problems caused by low signal
current (IS), the operation of devices at
various ambient temperatures, lot-to-lot
variation of quiescent current, and the
addition or replacement of devices to the bus
while in the field. At present, a maximum of
30 active devices can coexist on the same
bus, each with a different address. Address
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TYPICAL DEVICE QUIESCENT CURRENT
1.5
O
IN mA
2.0
QUIESCENT CURRENT, I
ofthe address cycle. This response may be
used as an indication that the device is "alive
and well" on the bus and is called the diagnostic response. If the device detects an
ambient magnetic field, it continues with I S
during the low portion of the address cycle.
This response from the device is called the
signal response. When the next positive
(address) transition is detected, the device
becomes disabled, and its contribution to the
bus signal current returns to IQ.
1.0
T A = +25°C
0.5
0
3
0
6
9
SUPPLY VOLTAGE, V
12
BUS
15
IN VOLTS
Dwg. GH-045
FIGURE 2
DEVICE CONNECTIONS
POSITIVE BUS SUPPLY
X
1
2
X
3
1
2
3
NC
SWITCH
BUS RETURN
Dwg. EH-004
5
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
FIGURE 3
(POSITIVE) BUS SUPPLY
ADDRESS
RESET
ANALOG OUT
INTERFACE
MICROPROCESSOR
BUS INTERCONNECTION
01
02
28
29
30
BUS RETURN
Dwg. EH-005
31 is designed to be inactive to allow for
further address expansion of the bus (to 62
maximum addresses). In order to repeat the
address cycle, the bus must be reset, as
shown in Figure 1, by bringing the supply
voltage to below VRST. Devices have been
designed not to ‘wrap-around’.
Magnetic Characteristics
The device IC has been designed to
respond to an external magnetic field whose
magnetic strength is greater than B OP. It
accomplishes this by amplifying the output of
an on-chip Hall transducer and applying it to
a threshold detector. In order that bus
current is kept to a minimum, the transducer
and amplification circuitry is kept powered
down until the device is addressed. Hence,
the magnetic status is evaluated only when
the device is addressed.
External Switch Sensing
Pin 3 of the IC may be used to detect the
status of an external switch when magnetic
field sensing is not desired (and in the
absence of a magnetic field). The allowable
states for the switch are ‘open’ or ‘closed’
(shorted to device ground).
6
APPLICATIONS NOTES
Magnetic Actuation
The left side of Figure 2 shows the wiring of an A3054KU or
A3054SU when used as a magnetic threshold detector. Pin 1 of the
device is wired to the positive terminal of the bus, pin 2 is connected to
the bus negative terminal, and pin 3 has no connection.
Mechanical Actuation
The right side of Figure 2 shows the wiring of an A3054KU or
A3054SU when used to detect the status of a mechanical switch.
In this case, pin 3 is connected to the switch. The other side of the
switch is connected to the bus return (negative bus supply or ground).
When the mechanical switch is closed, and the correct bus address is
detected by the IC, the device responds with a signal current. If the
switch is open, only the diagnostic current is returned.
Bus Configuration
A maximum of 30 individually addresable devices may be connected across the same two-wire bus as shown in Figure 3. It is
recommended that the devices use a dedicated digital ground wire to
minimize the effects of changing ground potential (as in the case of
chassis ground in the automotive industry).
The bus was not designed to require two-wire twisted pair wiring to
the devices. However, in areas of extreme electromagnetic interference, it may be advisable to install a small bypass capacitor (0.01 µF
for example) between the supply and ground terminals of each device
instead of using the more expensive wiring.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
Bus Driver
It is recommended that the bus be controlled
by microprocessor-based hardware for the
following reasons:
• The microprocessor can also be used to filter out random line noise
by digitally filtering the bus responses.
• The microprocessor can easily keep track of the signal responses
and initiate the appropriate action (e.g., light a lamp or sound an
alarm, and also pinpoint the location of the signal).
• Device address information may be stored
in ROM in the form of a look-up table.
Optimally, the microprocessor is used to control bus-driving
circuitry that will accept TTL-level inputs to drive the bus and will return
an analog voltage representation of the bus current.
• Bus faults can be pinpointed by the
microprocessor by comparing the diagnostic response to the expected response in
the ROM look-up table.
Interface Schematic
The bus driver is easily designed using a few operational amplifiers, resistors, and transistors. Figure 4 shows a schematic of a
recommended bus driver circuit that is capable of providing 6 V to 9 V
transitions, resetting the bus, and providing an analog measurement of
the bus current for the A/D input of the microprocessor.
• The microprocessor, along with an A/D
converter, can also be used to self calibrate the quiescent currents in the bus and
hence be able to easily detect a signal
response.
FIGURE 4
BUS INTERFACE SCHEMATIC
+15 V
1 kΩ
10 kΩ R 4
9V
Z1
1 kΩ
0.001
µF
OP1
BUS SUPPLY
20 kΩ
R5
ADDRESS
5 kΩ
Q3
50 Ω R
6
X
X
Q2
Q1
RESET
5 kΩ
50 kΩ
R7
50 kΩ
R8
1
2
3
1
2
3
NC
SWITCH
100 kΩ R 9
BUS RETURN
ANALOG OUT
OP2
100 kΩ
R 10
Dwg. EH-003A
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7
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
In Figure 4, the ADDRESS input provides a TTL-compatible input
to control the bus supply. A HIGH (5 V) input switches Q 1 ON and sets
the bus voltage to 6 V through the resistor divider R 4, R5, and Zener
Z1. A LOW input switches Q1 OFF and sets the bus voltage to 9 V
(Z1). This voltage is fed into the positive input of the operational
amplifier OP1 and is buffered and made available at BUS SUPPLY (or
device supply). Bus reset control is also available in the form of a TTLcompatible input. When the RESET input is HIGH, Q 2 is switched ON
and the positive input of the operational amplifier is set to the saturation voltage of the transistor (approximately 0 V). This resets the bus.
A linear reading of the bus current is made possible by amplifying
the voltage generated across R6 (which is IBUS • R6). The amplifier,
OP2, is a standard differential amplifier of gain R 9/R7 (provided that R7
= R8, R9 = R10). The gain of the total transim-pedance amplifier is
given by:
VOUT = IBUS • R6 • R9/R7
This voltage is available at the ANALOG OUT terminal.
Bus Control Software
The processing of the bus current (available at ANALOG OUT) is
best done by feeding it into the A/D input of a microprocessor. If the
flexibility provided by a microprocessor is not desired, this signal could
be fed into threshold detection circuitry; e.g., comparator, and the
output used to drive a display.
Related References
1. G. AVERY, “Two-Terminal Hall Sensor,” ASSIGNEE: Sprague
Electric Company, North Adams, MA, United States. Patent number
4,374,333; Feb. 1983.
2. T. WROBLEWSKI and F. MEISTERFIELD, “Switch Status
Monitoring System, Single-Wire Bus, Smart Sensor Arrangement
There Of,” ASSIGNEE: Chrysler Motor Corporation, Highland Park, Ml,
United States. Patent number 4,677,308; June 1987.
8
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
Dimensions in Inches
Dimensions in Millimeters
(controlling dimensions)
(for reference only)
0.183
0.178
4.65
4.52
0.063
0.059
1.60
1.50
0.181
0.176
4.60
4.47
45°
0.086
1
2
45°
0.018
3
2.18
MAX
1
2
0.46
3
MAX
0.0173
0.0138
0.600
0.560
15.24
14.23
0.44
0.35
0.0189
0.0142
0.48
0.36
SEE NOTE
SEE NOTE
0.050
0.100
1.27
2.54
Dwg. MH-003E in
Dwg. MH-003E mm
NOTES:1. Tolerances on package height and width represent allowable mold
offsets. Dimensions given are measured at the widest point
(parting line).
2. Exact body and lead configuration at vendor’s option within limits
shown.
3. Height does not include mold gate flash.
4. Recommended minimum PWB hole diameter to clear transition
area is 0.035” (0.89 mm).
5. Where no tolerance is specified, dimension is nominal.
6. Minimum lead length was 0.500” (12.70 mm). If existing product to
the original specifications is not acceptable, contact sales office
before ordering.
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9
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
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 appliances, 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 infringements of patents or other rights of
third parties that may result from its use.
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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