A1245
Chopper-Stabilized, Two Wire Hall-Effect Latch
FEATURES AND BENEFITS
DESCRIPTION
• High speed, 4-phase chopper stabilization
□ Low switchpoint drift throughout temperature range
□ Low sensitivity to thermal and mechanical stresses
• On-chip protection
□ Supply transient protection
□ Reverse battery protection
• On-board voltage regulator
The A1245 is a two-wire Hall-effect latch. The device is
producedontheAllegro™ advancedBiCMOSwaferfabrication
process,whichimplementsapatentedhighfrequency,4-phase,
chopper-stabilization technique. This technique achieves
magnetic stability over the full operating temperature range,
and eliminates offsets inherent in devices with a single Hall
element that are exposed to harsh application environments.
□ 3.0 to 24 V operation
• Solid-state reliability
• Industry leading ISO 7637-2 performance through use of
proprietary, 40 V clamping structures
Two-wirelatchesareparticularlyadvantageousincost-sensitive
applications because they require one less wire for operation
versus the more traditional open-collector output switches.
Additionally, the system designer inherently gains diagnostics
because there is always output current flowing, which should
be in either of two narrow ranges.Any current level not within
these ranges indicates a fault condition.
PACKAGES:
Not to scale
The Hall-effect latch will be in the high output current state
in the presence of a magnetic south polarity field of sufficient
magnitude and will remain in this state until a sufficient north
polarity field is present.
Approximate
footprints
The device is offered in two package styles. The LH is a
SOT-23W style, miniature low profile package for surface-
mount applications. The UA is a 3-pin ultra-mini single inline
packages (SIP) for through-hole mounting. Both packages are
lead (Pb) free, with 100% matte tin leadframe plating.
3-pin SOT23-W
2 × 3 × 1 mm
(suffix LH)
3-pin ultramini SIP
1.5 × 4 × 3 mm
(suffix UA)
VCC
V+
Regulator
Clock/Logic
Amp
To all subcircuits
Schmitt
Trigger
Low-Pass
Filter
Polarity
GND
UA package only
GND
Functional Block Diagram
A1245-DS, Rev. 1