US3881
CMOS Low Voltage Hall Effect Latch
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.
US3881
US3881
Temperature Suffix
Package
Temperature Range
E
SO or UA
-40
o
C to 85
o
C Commercial
L
SO or UA
-40
o
C to 150
o
C Automotive
* Contact factory or Sale Representative for legacy temperature options
Functional Diagram
Description
The US3881 is a bipolar Hall effect sensor IC fabri-
cated from mixed signal CMOS technology. It in-
corporates advanced chopper stabilization tech-
niques to provide accurate and stable magnetic
switch points. There are many applications for this
sensor in addition to those listed above. The de-
sign, 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 mag-
netic field facing the marked side of the package.
Similarly, the output will be latched off (B
RP
) in the
presence of a North field.
SO Package
Pin 1 - V
DD
Pin 2 - Output
Pin 3 - GND
V
DD
Output
Voltage
Regulator
Chopper
GND
UA Package
Pin 1 - V
DD
Pin 2 - GND
Pin 3 - Output
The SOT-23 device is reversed from the UA pack-
age. 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.
Note:
Static sensitive device; please observe ESD precautions. Re -
verse V
DD
protection is not included. For reverse voltage protec -
tion, a 100Ω resistor in series with V
DD
is recommended.
US3881 CMOS Low Voltage Hall Effect Latch
3901003881 Rev 4.2
7/23/01
Page 1
US3881
CMOS Low Voltage Hall Effect Latch
US3881 Electrical Specifications
DC Operating Parameters: T
A
= 25, V
DD
= 12V
DC
(unless otherwise specified).
Parameter
Supply Voltage
Supply Current
Saturation Voltage
Output Leakage
Output Rise Time
Output Fall Time
Symbol Test Conditions
V
DD
Operating
I
DD
V
DS(on)
I
OFF
t
r
t
f
B<B
OP
I
OUT
= 20 mA, B>B
OP
B<B
RP
, V
OUT
= 18V
V
DD
= 12V, R
L
= 1.1KÙ, C
L
= 20pf
V
DD
= 12V, R
L
= 1.1KÙ, C
L
= 20pf
Min
2.2
1.5
Typ
2.5
0.4
0.01
0.04
0.18
Max
18
4.0
0.5
5.0
Units
V
mA
V
ìA
ìs
ìs
US3881 Magnetic Specifications
DC Operating Parameters: T
A
= -40 to 150
o
C, V
DD
=12 V
DC
(unless otherwise specified). 1mT=10 Gauss.
Parameter
Operating Point
Release Point
Hysteresis
Symbol Test Conditions
B
OP
B
RP
B
hys
Min
1.0
-9.0
5.5
Typ
5.0
-5.0
10.0
Max
9.0
-1.0
12.0
Units
mT
mT
mT
Absolute Maximum Ratings
Supply Voltage (Operating), V
DD
Supply Current (Fault), I
DD
Output Voltage, V
OUT
Output Current (Fault), I
OUT
Power Dissipation, P
D
Operating Temperature Range, T
A
Storage Temperature Range, T
S
Maximum Junction Temp, T
J
ESD Sensitivity (All Pins)
18V
50mA
18V
50mA
100mW
-40 to 150°C
-65 to 150°C
175°C
+/- 4KV
Melexis Inc. reserves the right to make changes without further notice to any products herein to improve reliability, function o r design. Melexis
does not assume any liability arising from the use of any product or application of any product or circuit described herein.
US3881 CMOS Low Voltage Hall Effect Latch
3901003881 Rev 4.2
7/23/01
Page 2
US3881
CMOS Low Voltage Hall Effect Latch
Performance Graphs
Typical Magnetic Switch Points
versus
Supply Voltage
12.5
Typical Magnetic Switch Points
versus
Temperature
12.5
3881
3881
B
HYS
7.5
B
OP
2.5
7.5
Flux Density (mT)
Flux Density (mT)
B
OP
2.5
-2.5
B
RP
-7.5
-2.5
B
RP
-7.5
-12.5
0
5
10
15
20
25
30
-12.5
-40
0
40
80
120
160
200
Supply Voltage (V)
Temperature (
o
C)
Min/Max Magnetic Switch
Range
versus
Temperature
12.5
Output Voltage
versus
Flux Density
25
3881
3881
7.5
B Max
OP
20
V
DD
B
OP
Flux Density (mT)
Output Voltage (V)
2.5
B Min
OP
15
B
RP
10
-2.5
B
P
Max
R
-7.5
5
B
P
Min
R
V
out
-12.5
-40
0
0
40
80
120
160
200
-30
-20
-10
0
1
0
2
0
30
Temperature (
o
C)
Flux Density (mT)
US3881 CMOS Low Voltage Hall Effect Latch
3901003881 Rev 4.2
7/23/01
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US3881
CMOS Low Voltage Hall Effect Latch
Performance Graphs
Performance Graphs
Typical Supply Current
versus
Supply Voltage
5
Typical Saturation Voltage
versus
Temperature
V
DD
= 12 V, I
OUT
= 20mA
3881
500
3881
4
T
A
= -40
o
C
400
V
DS(ON)
Supply Current (mA)
V
DS(ON)
(mV)
3
T
A
=
25
o
C
300
2
T
A
= 125
o
C
200
1
100
0
0
5
10
15
20
25
30
0
-40
0
40
80
120
160
200
Supply Voltage (V)
Temperature (
o
C)
Power Dissipation
versus
Temperature
500
Wave Soldering Parameters
All Devices
All Devices
280
Package Power Dissipation (mW)
400
UAPackage
R
J A
=206
o
C/W
θ
300
o
Solder Temperature ( C)
260
240
200
220
100
SOPackage
R
θ
J A
=575
o
C/W
0
-40
200
0
40
80
120
160
200
0
5
10
15
20
25
30
Temperature (
o
C)
Time in Wave Solder (Seconds)
3901003881 Rev 4.2
7/23/01
Page 4
US3881 CMOS Low Voltage Hall Effect Latch
US3881
CMOS Low Voltage Hall Effect Latch
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 possi-
ble. The CMOS chip is also much smaller than
a bipolar chip, allowing very sophisticated cir-
cuitry to be placed in less space. The small chip
size also contributes to lower physical stress
and less power consumption.
Applications
If reverse supply protection is desired, use a re-
sistor 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.
Installation
Consider temperature coefficients of Hall IC and
magnetics, as well as air gap life time varia-
tions. Observe temperature limits during wave
soldering.
Applications Examples
Automotive and Severe
Environment Protection Circuit
R
1
100
Ω
V
DD
D1
Z1
C1
Supply
Voltage
4.7nF
Two Wire Optional Current
Biasing Circuit
R
L
I
DD
V
R
L
1.2K
OUT
C2
4.7nF
DD
I
IN
Iout
Hall IC
V
SS
R
b
Hall IC
The resistors R
b
and R
L
can be used to bias the input current, Iin.
Refer to the part specification for limiting values. This circuit will help in
getting the precise ON and OFF currents desired.
B
RP
= Ioff = (V
DD
/ Rb + I
DD
)
B
OP
= Ion = (Ioff + V
DD
/ R
L
)
US3881 CMOS Low Voltage Hall Effect Latch
3901003881 Rev 4.2
7/23/01
Page 5
PCB Design
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