US4881
Bipolar Hall Switch
Low Voltage & Very High Sensitivity
Features and Benefits
Operating voltage range from 2.2V to 18V
Very high magnetic sensitivity
CMOS technology
Chopper-stabilized amplifier stage
Low current consumption
Open drain output
SOT23 3L and flat TO-92 3L
both RoHS Compliant packages
Application Examples
Automotive, Consumer and Industrial
Solid-state switch
Brushless DC motor commutation
Speed detection
Linear position detection
Angular position detection
Proximity detection
Ordering Information
Part No.
US4881
US4881
US4881
US4881
US4881
US4881
Temperature Code
E (-40° to 85°
C
C)
E (-40° to 85°
C
C)
K (-40° to 125°
C
C)
K (-40° to 125°
C
C)
L (-40° to 150°C)
C
L (-40° to 150°C)
C
Package Code
SO (SOT23-3L)
UA (TO-92)
SO (SOT23-3L)
UA (TO-92)
SO (SOT23-3L)
UA (TO-92)
1 Functional Diagram
2 General Description
The Melexis US4881 is a bipolar Hall-effect switch
designed in mixed signal CMOS technology.
The device integrates a voltage regulator, Hall
sensor with dynamic offset cancellation system,
Schmitt trigger and an open-drain output driver, all
in a single package.
The low operating voltage and extended choice of
temperature range make it suitable for use in
automotive, industrial and consumer low voltage
applications.
The devices are delivered in a Small Outline
Transistor (SOT23) for surface mount process and
in a Plastic Single In Line (TO-92 flat) for through-
hole mount.
Both 3-lead packages are RoHS compliant.
3901004881
Rev 011
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Data Sheet
Feb/06
US4881
Bipolar Hall Switch
Low Voltage & Very High Sensitivity
Table of Contents
1 Functional Diagram ........................................................................................................ 1
2 General Description........................................................................................................ 1
3 Glossary of Terms .......................................................................................................... 3
4 Absolute Maximum Ratings ........................................................................................... 3
5 Pin Definitions and Descriptions................................................................................... 3
6 General Electrical Specifications .................................................................................. 4
7 Magnetic Specifications ................................................................................................. 4
8 Output Behaviour versus Magnetic Pole ...................................................................... 4
9 Detailed General Description ......................................................................................... 5
10 Unique Features............................................................................................................ 5
11 Performance Graphs .................................................................................................... 6
12 Application Information................................................................................................ 7
12.1 Typical Three-Wire Application Circuit ....................................................................................................7
12.2 Two-Wire Circuit ......................................................................................................................................7
12.3 Automotive and Harsh, Noisy Environments Three-Wire Circuit ............................................................7
13 Application Comments ................................................................................................. 7
14 Standard information regarding manufacturability of Melexis products with
different soldering processes........................................................................................... 8
15 ESD Precautions ........................................................................................................... 8
16 Package Information..................................................................................................... 9
16.1 SO Package (SOT23-3L).........................................................................................................................9
16.2 UA Package (TO-92 flat) .......................................................................................................................10
17 Disclaimer.................................................................................................................... 11
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Rev 011
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Data Sheet
Feb/06
US4881
Bipolar Hall Switch
Low Voltage & Very High Sensitivity
3 Glossary of Terms
MilliTesla (mT), Gauss
RoHS
TSOT
ESD
BLDC
Units of magnetic flux density:
1mT = 10 Gauss
Restriction of Hazardous Substances
Thin Small Outline Transistor (TSOT package) – also referred with the Melexis
package code “SE”
Electro-Static Discharge
Brush-Less Direct-Current
4 Absolute Maximum Ratings
Parameter
Symbol
Supply Voltage
V
DD
Supply Current
I
DD
Output Voltage
V
OUT
Output Current
I
OUT
Storage Temperature Range
T
S
Maximum Junction Temperature
T
J
ESD Sensitivity (AEC Q100 002)
-
Table 1: Absolute maximum ratings
Value
20
50
20
50
-50 to 150
165
2.5
Units
V
mA
V
mA
°C
°C
kV
Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute-maximum-
rated conditions for extended periods may affect device reliability.
Operating Temperature Range
Temperature Suffix “E”
Temperature Suffix “K”
Temperature Suffix “L”
Symbol
T
A
T
A
T
A
Value
-40 to 85
-40 to 125
-40 to 150
Units
°C
°C
°C
5 Pin Definitions and Descriptions
SE Pin
№
UA Pin
№
Name
1
1
VDD
2
3
OUT
3
2
GND
Table 2: Pin definitions and descriptions
Type
Supply
Output
Ground
Function
Supply Voltage pin
Open Drain Output pin
Ground pin
SO package
UA package
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Data Sheet
Feb/06
US4881
Bipolar Hall Switch
Low Voltage & Very High Sensitivity
6 General Electrical Specifications
DC Operating Parameters T
A
= 25 C, V
DD
= 12V (unless otherwise specified)
Parameter
Symbol
Supply Voltage
V
DD
Supply Current
I
DD
Output Saturation Voltage
V
DSon
Output Leakage Current
I
OFF
Output Rise Time
t
r
Output Fall Time
t
f
Maximum Switching Frequency
F
SW
SO Package Thermal Resistance
R
TH
UA Package Thermal Resistance
R
TH
Table 3: Electrical specifications
Test Conditions
Operating
B < B
RP
I
OUT
= 20mA, B > B
OP
B < B
RP,
V
OUT
= 24V
R
L
= 1kΩ, C
L
= 20pF
R
L
= 1kΩ, C
L
= 20pF
Min
2.2
1.5
Typ
Max
18
5
0.5
10
Units
V
mA
V
µA
µs
µs
KHz
°C/W
°C/W
o
0.01
0.25
0.25
10
350
200
7 Magnetic Specifications
DC Operating Parameters T
A
= 25 C, V
DD
= 12V (unless otherwise specified)
Parameter
Symbol
Operating Point
B
OP
Release Point
B
RP
Hysteresis
B
HYST
Table 4: Magnetic specifications
Test Conditions
Min
-1
-6
2
Typ
Max
6
1
6
Units
mT
mT
mT
o
Note 1: For typical values, please refer to the performance graphs in section 11
8 Output Behaviour versus Magnetic Pole
DC Operating Parameters T
A
= -40 C to 150 C, V
DD
= 2.2V to 18V (unless otherwise specified)
Parameter
Test Conditions (SO) OUT (SO) Test Conditions (UA)
South pole
B < B
RP
High
B > B
OP
North pole
B > B
OP
Low
B < B
RP
Table 5: Output behaviour versus magnetic pole
OUT (UA)
Low
High
o
o
South pole
North pole
North pole
OUT = high
South pole
OUT = low (V
DSon
)
UA package
OUT = high
OUT = low (V
DSon
)
SO package
3901004881
Rev 011
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Data Sheet
Feb/06
US4881
Bipolar Hall Switch
Low Voltage & Very High Sensitivity
9 Detailed General Description
Based on mixed signal CMOS technology, Melexis US4881 is a Hall-effect device with very high magnetic
sensitivity. It allows using generic magnets, weak magnets or larger air gap.
The chopper-stabilized amplifier uses switched capacitor techniques to suppress the offset generally
observed with Hall sensors and amplifiers. The CMOS technology makes this advanced technique possible
and contributes to smaller chip size and lower current consumption than bipolar technology. The small chip
size is also an important factor to minimize the effect of physical stress.
This combination results in more stable magnetic characteristics and enables faster and more precise design.
The operating voltage from 2.2V to 18V, low current consumption and large choice of operating temperature
range according to “L”, “K” and “E” specification make this device suitable for automotive, industrial and
consumer low voltage applications.
The output signal is open-drain type. Such output allows simple connectivity with TTL or CMOS logic by using
a pull-up resistor tied between a pull-up voltage and the device output.
10 Unique Features
The US4881 exhibits bipolar magnetic switching characteristics. Therefore, it operates with both south and
north poles.
Typically, the device behaves as a latch with symmetric
operating and release switching points (B
OP
=|B
RP
|). This means
magnetic fields with equivalent strength and opposite direction
drive the output high and low.
Removing the magnetic field (B→0) keeps the output in its
previous state. This latching property defines the device as a
magnetic memory.
Latch characteristic
Depending on the magnetic switching points, the device may also behave as a unipolar positive switch (B
OP
and B
RP
strictly positive) or negative switch (B
OP
and B
RP
strictly negative). That is the output can be set high
and low by only using one magnetic pole. In such case, removing the magnetic field changes the output level.
Unipolar positive switch characteristic
Unipolar negative switch characteristic
In latch, positive or negative switch behaviour, a magnetic hysteresis B
HYST
keeps B
OP
and B
RP
separated by
a minimal value. This hysteresis prevents output oscillation near the switching point.
3901004881
Rev 011
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Data Sheet
Feb/06
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