3054
MULTIPLEXED TWO-WIRE
HALL-EFFECT SENSOR ICs
The A3054KU and A3054SU Hall-effect sensors are digital mag-
netic sensing ICs capable of communicating over a two-wire power/
signal bus. Using a sequential addressing scheme, the device re-
sponds 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 sensors 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.
Each device consists of high-resolution bipolar Hall-effect switch-
ing 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 magnetic-
field or switch-status sensing, low-noise amplification of the Hall-
transducer output, and high-density decoding and control logic is made
possible by the development of a new sensor 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 tempera-
ture 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 specifica-
tions 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).
Data Sheet
27680.1*
LOGIC
1
2
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
°
C
Supply Voltage, V
BUS
. . . . . . . . . . . . . .
18 V
Magnetic Flux Density, B . . . . . . .
Unlimited
Operating Temperature Range, T
A
A3054KU . . . . . . . . . .
-40
°
C to +125
°
C
A3054SU . . . . . . . . . . . .
-20
°
C to +85
°
C
Storage Temperature Range,
T
S
. . . . . . . . . . . . . . . .
-55
°
C to +150
°
C
Package Power Dissipation,
P
D
. . . . . . . . . . . . . . . . . . . . . . .
635 mW
1
0
0
Y
1, 2
U
3
B
t.
E
Oc
IM
ntil
-T
u
T
d
S
te
A
ep
L
c
c
a
rs
e
rd
O
GROUND
BUS
Dwg. PH-005
SWITCH IN
X
3
FEATURES
s
s
s
s
s
s
s
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 Sensors Can Share a Bus
Sensor Diagnostic Capabilities
Magnetic-Field or Switch-Status Sensing
Low Power of DABiC Technology Favors
Battery-Powered and Mobile Applications
Ideal for Automotive, Consumer, and Industrial Applications
Always order by complete part number:
Part Number
A3054KU-XX
A3054SU-XX
-40°C to +125°C
-20°C to +85°C
Operating Temperature Range
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
Signal Current
Quiescent Current
Symbol
V
BUS
I
S
I
QL
I
QH
∆I
Q
Address Range
Clock Thresholds
Addr
V
CLH
V
CHL
V
CHYS
Max. Clock Frequency*
Address LOW Voltage
Address HIGH Voltage
Reset Voltage
Propagation Delay*
f
CLK
V
L
V
H
V
RST
t
plh
t
phl
Pin 3-2 Resistance
R
SWH
R
SWL
Pin 3-2 Output Voltage
V
SWH
V
SWL
LOW to HIGH
HIGH to LOW
DUT Addressed, B < 5 G
DUT Addressed, B > 300 G
DUT Addressed, B < 5 G
DUT Addressed, B> 300 G
DUT Addressed, B > 300 G
V
BUS
= 6 V
V
BUS
= 9 V
I
QL
– I
QH
Factory Specified
LOW to HIGH
HIGH to LOW
Hysteresis
50% Duty Cycle
Test Conditions
Min
—
12
—
—
—
1
—
6.5
—
2.5
V
RST
V
CLH
2.5
10
—
—
—
—
—
Typ
—
15
1.5
1.4
100
—
—
—
0.8
—
6.0
9.0
3.5
20
5.0
50
200
3.9
30
Max
15
20
2.5
2.5
300
30
8.5
—
—
—
V
CHL
V
BUS
5.5
30
10
—
—
—
—
Units
V
mA
mA
mA
µA
—
V
V
V
kHz
V
V
V
µs
µs
kΩ
Ω
V
mV
MAGNETIC CHARACTERISTICS over operating temperature range.
Limits
Characteristic
Magnetic Threshold†
Symbol
B
OP
B
RP
Hysteresis
B
HYS
Test Conditions
Turn-On
Turn-Off
B
OP
– B
RP
Min.
50
5.0
5.0
Typ.
150
100
50
Max.
300
295
—
Units
G
G
G
Typical Data is at T
A
= +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
(±0.005 [0.13 mm] die placement)
ACTIVE AREA DEPTH
0.0165"
0.42 mm
NOM
0.090"
2.29 mm
SENSOR LOCATION
FUNCTIONAL BLOCK DIAGRAM
1
BUS
REG
0.073"
1.85 mm
COMP
COMP
CLOCK
CMOS LOGIC
RESET
A
BRANDED
SURFACE
1
2
3
2
Dwg. MH-002-10B
3
SWITCH IN
(OPTIONAL)
GROUND
Dwg. FH-009
DEFINITION OF TERMS
Sensor Address
Each bus sensor has a factory-specified predefined
address. At present, allowable sensor addresses are
integers from 01 to 30.
LOW-to-HlGH Clock Threshold (V
CLH
)
Minimum voltage required during the positive-going
transition to increment the bus address and trigger a
diagnostic response from the bus sensors. This is also
the maximum threshold of the on-chip comparator that
monitors the supply voltage, V
BUS
.
HlGH-to-LOW Threshold (V
HL
)
Maximum voltage required during the negative-going
transition to trigger a
signal
current response from the bus
sensors. This is also the maximum threshold of the
on-chip comparator that monitors the supply voltage,
V
BUS
.
Bus HIGH Voltage (V
H
)
Bus HIGH voltage during addressing. Voltage should
be greater than V
CLH
.
Address LOW Voltage (V
L
)
Bus LOW voltage during addressing. Voltage should
be greater than V
RST
and less than V
CHL
.
Bus Reset Voltage (V
RST
)
Voltage level while resetting sensors.
Sensor Quiescent Current Drain (I
Q
)
The current drain of bus sensors when active but not
addressed. I
QH
is the quiescent current drain when the
sensor is not addressed and is at V
H
I
QL
is the quiescent
current drain when the sensor is not addressed and is at
V
L
. Note that I
QL
is greater than I
QH
.
Diagnostic Phase
Period on the bus when the address voltage is at V
H
.
During this period, a correctly addressed sensor responds
by increasing its current drain on the bus. This response
from the sensor 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 sensor that
detects a magnetic field greater than the magnetic oper-
ate point, B
OP
, responds by maintaining a current drain of
I
S
on the bus. This response from the sensor is called the
signal response
and the bus current is called the
signal
current.
Sensor Address Response Current (I
S
)
Sensor current during the
diagnostic
and the
signal
responses of the bus sensor. This is accomplished by
enabling an internal constant-current source.
Allegro
3
www.allegromicro.com
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
ADDRESSING PROTOCOL
Magnetic Operate Point (B
OP
)
Minimum magnetic field required to switch ON the
Hall amplifier and switching circuitry of the addressed
sensor. This circuitry is only active when the sensor is
addressed.
Magnetic Release Point (B
RP
)
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 (B
HYS
)
Difference between the B
OP
and B
RP
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 V
L
and V
H
(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.
Sensor Addressing
When a sensor 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
V
H
V
CLH
DIAGNOSTIC
ADDRESS 01
DIAGNOSTIC
ADDRESS 02
DIAGNOSTIC
ADDRESS 03
DIAGNOSTIC
ADDRESS 04
DIAGNOSTIC
ADDRESS
n
DIAGNOSTIC
ADDRESS 01
BUS
VOLTAGE
V
CHL
V
L
RESET
V
RST
0
t plh
t phl
RESET
IS
SENSOR 02 —
DIAGNOSTIC CURRENT
SENSOR 02
CURRENT
WITH NO
MAGNETIC
FIELD
I QL
I QH
0
IS
SENSOR 03 — DIAGNOSTIC
AND SIGNAL CURRENTS
SENSOR 03
CURRENT
WITH
MAGNETIC
FIELD
I QL
I QH
0
I
S
TOTAL
BUS CURRENT
WITH
MAGNETIC
FIELD AT
SENSOR 03
SENSOR 01
NOT PRESENT
n • I QL
n • IQH
0
SENSOR 01
NOT PRESENT
Dwg. WH-005
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3054
MULTIPLEXED
TWO-WIRE
HALL-EFFECT SENSOR ICs
ofthe address cycle. This response may be
used as an indication that the sensor is "alive
and well" on the bus and is called the
diag-
nostic
response. If the sensor detects an
ambient magnetic field, it continues with I
S
during the low portion of the address cycle.
This response from the sensor is called the
signal
response. When the next positive
(address) transition is detected, the sensor
becomes disabled, and its contribution to the
bus signal current returns to I
Q
.
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 repre-
sents the bus current contribution of Sensor
02. The
diagnostic
response from the sensor
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 Sensor 03
when a magnetic field is detected. Note both
the
diagnostic
and
signal
currents from the
sensor. The last trace represents the overall
bus current drain. When no sensors are
addressed, the net bus current is the sum of
quiescent currents of all sensors on the bus
(for 'n' sensors, the bus current drain is
n • I
Q
).
Bus Issues
After a reset, while at the address LOW
voltage (VL), and before the first address
pulse, bus current calibration may be per-
formed. This feature allows for fail-safe
detection of signal current and eliminates
detection problems caused by low signal
current (I
S
), the operation of sensors at
various ambient temperatures, lot-to-lot
variation of quiescent current, and the
addition or replacement of sensors to the bus
while in the field. At present, a maximum of
30 active sensors can coexist on the same
bus, each with a different address. Address
TYPICAL DEVICE QUIESCENT CURRENT
2.0
QUIESCENT CURRENT, I
O
IN mA
1.5
1.0
T
A
= +25°C
0.5
0
0
3
6
9
12
15
SUPPLY VOLTAGE, V
BUS
IN VOLTS
Dwg. GH-045
FIGURE 2
SENSOR CONNECTIONS
POSITIVE BUS SUPPLY
X
X
1
2
3
1
2
3
NC
SWITCH
BUS RETURN
Dwg. EH-004
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5
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