A1245: Chopper-Stabilized, Two Wire Hall-Effect Latch


 Allegro MicroSystems recommends APS12400 for all new Automotive 2-wire Hall-Effect latch IC designs.

The A1245 is a two-wire Hall-effect latch. The device is produced on the Allegro™ advanced BiCMOS wafer fabrication process, which implements a patented high frequency, 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.

Two-wire latches are particularly advantageous in cost-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.

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.

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.

Top Features

  • 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
    • 3.0 to 24 V operation
  • Operation up to 175°C junction temperature
  • Solid-state reliability
  • Industry leading ISO 7637-2 performance through use of proprietary, 40 V clamping structures

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A1245LUA-I1-T 3-lead SIP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock
A1245LUA-I2-T 3-lead SIP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.



Related Resources