3901003881
Page 1
Sept/02
Rev. 012
Features and Benefits
Chopper stabilized amplifier stage
Optimized for BDC motor applications
New miniature package / thin, high reliability package
Operation down to 2.2V
CMOS for optimum stability, quality, and cost
Applications
Solid state switch
Brushless DC motor commutation
Speed sensing
Linear position sensing
Angular position sensing
Current sensing
Ordering Information
Part No.
Temperature Suffix
Package
US3881
E (-40C to 85C)
SO (SOT-23) or UA (TO-92)
US3881
L (-40C to 150C)
SO (SOT-23) or UA (TO-92)
* Contact factory or Sale Representative for legacy temperature options
Description
The US3881 is a bipolar Hall effect sensor IC
fabricated from mixed signal CMOS technology. It
incorporates
advanced
chopper
stabilization
techniques to provide accurate and stable magnetic
switch points. There are many applications for this
sensor in addition to those listed above. The design,
specifications,
and
performance
have
been
optimized for commutation applications in 5V and
12V brushless DC motors.
The output transistor will be latched on (B
OP
) in the
presence of a sufficiently strong South pole
magnetic field facing the marked side of the
package. Similarly, the output will be latched off
(B
RP
) in the presence of a North field.
The SOT-23 device is reversed from the UA
package. The SOT-23 output transistor will be
latched on in the presence of a sufficiently strong
North pole magnetic field subjected to the marked
face.
Functional Diagram
Note: Static sensitive device; please observe ESD precautions.
Reverse V
DD
protection is not included. For reverse voltage
protection, a 100W resistor in series with V
DD
is recommended.
3901003881
Page 2
Sept/02
Rev. 012
Melexis Inc. reserves the right to make changes without further notice to any products herein to improve reliability, function or design. Melexis
does not assume any liability arising from the use of any product or application of any product or circuit described herein.
Absolute Maximum Ratings
Supply Voltage (Operating), V
DD
18V
Supply Current (Fault), I
DD
50mA
Output Voltage, V
OUT
18V
Output Current (Fault), I
OUT
50mA
Power Dissipation, P
D
100mW
Operating Temperature Range, T
A
-40 to 150C
Storage Temperature Range, T
S
-65 to 150C
Maximum Junction Temp, T
J
175C
US3881 Electrical Specifications
DC Operating Parameters: T
A
= 25, V
DD
= 12V
DC
(unless otherwise specified).
Parameter
Symbol Test Conditions
Min
Typ
Max
Units
Supply Voltage
V
DD
Operating
2.2
18
V
Supply Current
I
DD
B<B
OP
1.5
2.5
4.0
mA
Saturation Voltage
V
DS(on)
I
OUT
= 20 mA, B>B
OP
0.4
0.5
V
Output Leakage
I
OFF
B<B
RP
, V
OUT
= 20V
0.01
10.0
A
Output Rise Time
t
r
V
DD
= 12V, R
L
= 1.1K
, C
L
= 20pf
0.04
s
Output Fall Time
t
f
V
DD
= 12V, R
L
= 1.1K
, C
L
= 20pf
0.18
s
US3881 Magnetic Specifications
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
Operating Point
B
OP
EUA,ESO 25 & 85C, Vdd=2.2 & 18 volts DC
1.0
5.0
9.0
mT
Release Point
B
RP
EUA,ESO 25 & 85C, Vdd=2.2 & 18 volts DC
-9.0
-5.0
-1.0
mT
Hysteresis
B
hys
EUA,ESO 25 & 85C, Vdd=2.2 & 18 volts DC
5.5
10.0
12.0
mT
Operating Point
B
OP
LUA, LSO 25 & 150C, Vdd=2.2 & 18 volts DC
1.0
5.0
9.0
mT
Release Point
B
RP
LUA,LSO 25 & 150C, Vdd=2.2 & 18 volts DC
-9.0
-5.0
-1.0
mT
Hysteresis
B
hys
LUA,LSO 25 & 150C, Vdd=2.2 & 18 volts DC
5.5
10.0
12.0
mT
3901003881
Page 3
Sept/02
Rev. 012
Performance Graphs
Typical Magnetic Switch Points
vs. Vdd
-12.5
-10.0
-7.5
-5.0
-2.5
0.0
2.5
5.0
7.5
10.0
12.5
0.0
5.0
10.0
15.0
20.0
Vdd (V)
F
i
e
l
d
S
t
r
e
n
g
t
h
(
m
T
)
3881
3901003881
Page 4
Sept/02
Rev. 012
Performance Graphs
3901003881
Page 5
Sept/02
Rev. 012
Unique Features
CMOS Hall IC Technology
The chopper stabilized amplifier uses switched
capacitor techniques to eliminate the amplifier
offset voltage, which, in bipolar devices, is a
major source of temperature sensitive drift.
CMOS makes this advanced technique possible.
The CMOS chip is also much smaller than a
bipolar chip, allowing very sophisticated circuitry
to be placed in less space. The small chip size
also contributes to lower physical stress and less
power consumption.
Installation
Consider temperature coefficients of Hall IC and
magnetics, as well as air gap life time variations.
Observe
temperature
limits
during
wave
soldering.
Applications
If reverse supply protection is desired, use a
resistor in series with the V
DD
pin. The resistor
will limit the Supply Current (Fault), I
DD
, to 50
mA. For severe EMC conditions, use the
application circuit below.
Applications Examples
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