A3250 and A3251
A3250-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
AB SO LUTE MAX I MUM RAT INGS
Supply Voltage, V
CC
......................................26.5 V
Reverse-Supply Voltage, V
RCC
........................–18 V
Zener Overvoltage, V
Z
.......................................30 V
Output Current, I
OUT
.........................................20 mA
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Ambient, T
A
, Range J................. –40ºC to 115ºC
Ambient, T
A
, Range L................–40ºC to 150ºC
Maximum Junction, T
J(max)
........................165ºC
Storage Temperature, T
S
..................–65ºC to 170ºC
On-chip protection against:
null Supply transients
null Output short-circuits
null Reverse-battery condition
Field-Programmable, Chopper-Stabilized
Unipolar Hall-Effect Switches
Features and Benefits
The A3250 and A3251 are field-programmable, chopper-stabilized, unipolar Hall-
effect switches designed for use in high-temperature applications. These devices
use a chopper-stabilization technique to eliminate offset inherent in single-element
devices.
The A3250 and A3251 are externally programmable devices. The devices have a
wide range of programmability of the magnetic operate point (B
OP
) while the hys-
teresis remains fixed. This advanced feature allows for optimization of the sensor
switchpoint and can drastically reduce the effects of variations found in a produc-
tion environment, such as magnet and device placement tolerances.
These devices provide on-chip transient protection. A Zener clamp on the power
supply protects against overvoltage conditions on the supply line. These devices
also include short-circuit protection on the output.
The output of the A3250 switches LOW when subjected to a south-polarity mag-
netic field with a flux density that exceeds the threshold for B
OP
, and switches
HIGH when the field drops below the magnetic release point, B
RP
. The output of
the A3251 has the opposite polarity, switching HIGH in a south-polarity magnetic
field that B
OP
, and switching LOW when the field drops below B
RP
.
The other differences in the devices are the power-on state. The A3250 powers-on
in the HIGH state, while the A3251 powers-on in the LOW state.
These devices are available in a TO-92 three-lead ultra-mini SIP (Single In-line
Package), with either straight or formed and trimmed lead configuration.
1. VCC
2. GND
3. VOUT
Package UA, 3-pin SIP
Chopper stabilization for stable switchpoints
throughout operating temperature range
Externally programmable operate point
(through VCC pin)
On-board voltage regulator for 4.2 V to 24 V
operation
231
TL Option
Part Number Package
T
A
(ºC)
B
hys(typ)
(G)
V
OUT
Power-On Running*
A3250JUA
A3250JUATL
Straight lead
Formed lead
–40 to 115 18
High Low
A3250LUA
A3250LUATL
Straight lead
Formed lead
–40 to 150 13
A3251JUA
A3251JUATL
Straight lead
Formed lead
–40 to 115 18
Low High
A3251LUA
A3251LUATL
Straight lead
Formed lead
–40 to 150 13
*In south polarity magnetic field of sufficient strength.
Use the following complete part numbers when ordering: