A1250 Datasheet, PDF (1/12 Pages) Allegro MicroSystems – Hall Effect Latch / Bipolar Switch

A1250
Hall Effect Latch / Bipolar Switch
Features and Benefits
• High speed, 4-phase chopper stabilization
• Low operating voltage down to 3.0 V
• High Sensitivity
• Stable switchpoints
• Robust EMC
Packages: 3-pin SOT23W (suffix LH), and
3-pin SIP (suffix UA)
Not to scale
Description
The A1250 Hall-effect sensor IC is a temperature stable,
stress-resistant bipolar switch. This device is the most sensitive
Hall-effect device in the Allegro® bipolar switch family and is
intended for ring-magnet sensing. Superior high-temperature
performance is made possible through an Allegro patented
dynamic offset cancellation that utilizes chopper-stabilization.
This method reduces the offset voltage normally caused by
device overmolding, temperature dependencies, and thermal
stress.
The A1250 includes the following on a single silicon chip:
a voltage regulator, Hall-voltage generator, small-signal
amplifier, chopper stabilization, Schmitt trigger, and a short
circuit protected open-drain output. Advanced BiCMOS
wafer fabrication processing takes advantage of low-voltage
requirements, component matching, very low input-offset
errors, and small component geometries.
The A1250 Hall-effect bipolar switch turns on in a south
polarity magnetic field of sufficient strength and switches
off in a north polarity magnetic field of sufficient strength.
Because the output state is not defined if the magnetic field
is diminished or removed, to ensure that the device switches,
Allegro recommends using magnets of both polarities and of
sufficient strength in the application.
Continued on the next page…
Functional Block Diagram
V+
VCC
Regulator
To All Subcircuits
Clock / Logic
Amp
Low-Pass
Filter
Control
Current
Limit
VOUT
1Ω
GND
A1250-DS, Rev. 1