NOT RECOMMENDED FOR NEW DESIGN
USE
AH3781
AH921
HIGH SENSITIVITY CMOS HALL-EFFECT LATCH
Description
The AH921 is a Hall-effect latch designed in mixed signal CMOS
technology. It is quite suitable for use in automotive, industrial and
consumer applications.
Superior high-temperature performance is made possible through
dynamic offset cancellation, which reduces the residual offset voltage
normally caused by device over-molding, temperature dependencies,
and thermal stress. The device integrates a voltage regulator, Hall-
voltage generator, small-signal amplifier, chopper stabilization,
schmitt trigger, and is directly drivable by the output.
An on-board regulator permits operation with supply voltage from
3.5V to 24V.
The AH921 is available in TO-92S-3 and SOT-23-3 packages, which
are optimized for most applications.
Pin Assignments
(Front View)
3
2
1
OUT
GND
VCC
TO-92S-3
(Top View)
GND
3
Features
Wide Operating Voltage Range from 3.5V to 24V
Symmetrical Switch Points
Chopper-stabilized Amplifier Stage
Superior Temperature Stability
Compact Size
Built-in Pull-up Resistor
Wide Operating Temperature Range: -40º to +125º
C
C
ESD Rating: 3500V (Human Body Model)
Totally Lead-free & Fully RoHS Compliant (Note 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
1
2
VCC
OUT
SOT-23-3
Applications
Brushless DC Motor Commutation
Brushless DC Fan
Solid-state Switch
Revolution Counting
Speed Detection
High Sensitivity and Unconnected Switch
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit
OUT
Output
OUT
Output
AH921
AH921
GND
GND
VCC
C
L
0.1mF
C
L
0.1mF
V
CC
AH921
Document number: DS37028 Rev. 3 -3
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VCC
V
CC
June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH3781
AH921
Absolute Maximum Ratings
(Note 4)
Symbol
V
CC
I
CC
I
OUT
Supply Voltage
Supply Current (Fault)
Output Current (Continuous)
TO-92S-3
P
D
Power Dissipation
SOT-23-3
T
A
T
STG
T
J
(Max)
ESD
Operating Temperature
Storage Temperature
Maximum Junction Temperature
ESD (Human Body Model)
-50 to +150
-65 to +150
+165
3500
230
º
C
º
C
º
C
V
Parameter
Rating
28
5
25
400
mW
Unit
V
mA
mA
Note 4: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied.
Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.
Recommended Operating Conditions
Symbol
V
CC
T
A
Supply Voltage
Parameter
Min
3.5
-40
Max
24
+125
Unit
V
º
C
Operating Temperature
AH921
Document number: DS37028 Rev. 3 -3
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June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH3781
AH921
Electrical Characteristics
Symbol
V
CC
I
CC
Parameter
Supply Voltage
Supply Current
(@V
CC
=12V, T
A
=+25° unless otherwise specified. Notes 5 & 6.)
C,
Conditions
Operating
B<B
RP
B>B
OP
V
CC
=3.5V, I
OUT
=5mA, B>B
OP
(Note 7)
Min
3.5
–
–
–
–
–
–
–
–
Typ
12
3.0
3.0
50
185
185
0.1
0.4
0.4
Max
24
5.0
Unit
V
mA
5.0
120
500
500
10
2
2
μA
mV
V
SAT
Saturation Voltage
I
OUT
=20mA, B>B
OP
(Note 7)
V
CC
=24V, I
OUT
=20mA, B>B
OP
(Note 7)
I
LEAKAGE
t
RISING
t
FALLING
Notes:
Output Leakage Current
Output Rising Time
Output Falling Time
V
CC
=V
OUT
=24V, B<B
RP
(Note 8)
C
L
=20pF
C
L
=20pF
5. Output initial status is low when powering on.
6. The supply current I
CC
represents the average supply current. The output is open during measurement.
7. The device is put under the magnetic field: B>B
OP.
8. The device is put under the magnetic field: B<B
RP.
Magnetic Characteristics
(@V
CC
=12V, T
A
=+25° unless otherwise specified.)
C,
Symbol
B
OP
B
RP
B
HYS
Operating Point
Releasing Point
Hysteresis
Parameter
Min
5
-40
–
Typ
22
-22
45
Max
40
-5
–
Unit
Gauss
Gauss
Gauss
V
OUT
V
OUT
V
CC
V
d
High
B
HYS
V
d
V
CC
High
B
HYS
V
SAT
N
B
RP
0
B
OP
S
Low
Low
B
RP
N
0
For SOT-23-3
B
OP
S
V
SAT
For TO-92S-3
Figure 1. Magnetic Flux Density of AH921
AH921
Document number: DS37028 Rev. 3 -3
4 of 14
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June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH3781
AH921
Magnetic Characteristics
(Cont.)
South Pole
North Pole
Output=Low (For TO-92S-3)
Output=High (For TO-93S-3)
South Pole
North Pole
Output=High (For SOT-23-3)
Output=Low (For SOT-23-3)
Figure 2. Output Status vs. Magnetic Pole
Package Type
TO-92S-3
Parameter
South Pole
North Pole
South Pole
Test Condition
B＞B
OP
B＜B
RP
B＞B
OP
B＜B
RP
Output
Low
High
High
Low
SOT-23-3
North Pole
Table 1. Output Status vs. Magnetic Pole
AH921
Document number: DS37028 Rev. 3 -3
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June 2017
© Diodes Incorporated
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