A1128 Datasheet, PDF (1/20 Pages) Allegro MicroSystems – Highly Programmable Hall-Effect Switch

A1128
Highly Programmable Hall-Effect Switch
Features and Benefits
• Chopper stabilization for stable switchpoints throughout
operating temperature range
• Externally programmable:
▫ Operate point (through the VCC pin)
▫ Output polarity
▫ Output fall time for reduced EMI in
automotive applications
• On-board voltage regulator for 3 to 24 V operation
• On-chip protection against:
▫ Supply transients
▫ Output short-circuits
▫ Reverse battery condition
Packages: 3-pin SIP (suffix UA) and 3-pin
SOT89 (suffix LT)
Description
TheA1128 is a field-programmable, unipolar Hall-effect switch
designed for use in high-temperature applications. This device
uses a chopper-stabilization technique to eliminate offset
inherent in single-element devices.
The devices are externally programmable. A wide range of
programmability is available on the magnetic operate point,
B_OP , while the hysteresis remains fixed. This advanced
feature allows optimization of the sensor IC switchpoint and
can drastically reduce the effects of mechanical placement
tolerances found in end-use production environments.
A proprietary dynamic offset cancellation technique, with
an internal high-frequency clock, reduces the residual offset
voltage, which is normally caused by device overmolding,
temperature dependencies, and thermal stress. Having the Hall
element and amplifier in a single chip minimizes many problems
normally associated with low-level analog signals.
Two package styles provide a magnetically optimized package
for most applications. Type LT is a miniature SOT89/TO-243AA
surface mount package that is thermally enhanced with an
exposed ground tab, and type UA is a three-lead ultramini SIP
for through-hole mounting. The packages are lead (Pb) free,
with 100% matte tin plated leadframes.
Not to scale
V+
VCC
C_BYPASS
Functional Block Diagram
Regulator
Trim Control
To All Subcircuits
TC Trim
Switchpoint
GND
Amp
Signal Recovery
Program Control
Output Fall Time
Output Polarity
VOUT
A1128-DS, Rev. 1