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Related Links:

Datasheets:
A1242: Two-Wire Chopper-Stabilized Hall Effect Latch (PDF)

Selection Guides:
Hall-Effect Sensors,

Hall-Effect Digital Latches

when this product is updated

Press Releases:
A1242: Allegro MicroSystems, Inc. Introduces New Chopper-Stabilized Latch

A1242
Two-Wire Chopper-Stabilized Hall Effect Latch

Features and Benefits

• Chopper stabilization
  – Superior temperature stability
  – Extremely low switchpoint drift
  – Insensitive to physical stress
• Reverse battery protection
• Solid-state reliability
• Small size
• Robust EMC capability
• High ESD ratings (HBM)

Description

The A1242 Hall effect latch is a two-wire latch especially suited for operation over extended temperature ranges, from –40 to +150°C. Superior high-temperature performance is made possible through the Allegro® patented dynamic offset cancellation technique, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.

The current-switching output technique allows for the reduction in cost in the wiring harness because only two connections to the sensor are required. The current- switching output structure also inherently provides more immunity against EMC/ESD transients. These sensors have low magnetic thresholds, thereby enabling more flexibility in the magnetic circuit design.

The Hall effect latch will be in the high output current state in the presence of a magnetic South Pole field of sufficient magnitude and will remain in this state until a sufficient North Pole field is present.

The A1242 includes the following on a single silicon chip: a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a current source output. Advanced BiCMOS wafer fabrication processing takes advantage of low-voltage requirements, component matching, very low input-offset errors and small component geometries.

Suffix ‘L-’ devices are rated for operation over a temperature range of –40°C to +150°C; suffix ‘E-’ devices are rated for operation over a temperature range of –40°C to +85°C. Two A1242 package styles provide magnetically optimized solutions for most applications. Package LH is a SOT23W, a miniature low-profile surface-mount package, while package UA is a three-lead ultra-mini SIP for through-hole mounting. Each package is available lead (Pb) free, with 100% matte tin plated leadframes.

Functional Block Diagram

Complete Part Numbers

Part Number	Package Type	RoHS Compliant	Part Composition/ RoHS Data	Temperature	Comments	Samples	Distributor Stock
A1242ELHLT-I1-T	3-lead SOT	Yes	view data	-40 °C to  85 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242EUA-I1-T	3-pin SIP	Yes	view data	-40 °C to  85 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242LLHLT-I1-T	3-lead SOT	Yes	view data	-40 °C to  150 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242LUA-I1-T	3-pin SIP	Yes	view data	-40 °C to  150 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242ELHLT-I2-T	3-lead SOT	Yes	view data	-40 °C to  85 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242EUA-I2-T	3-pin SIP	Yes	view data	-40 °C to  85 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242LLHLT-I2-T	3-lead SOT	Yes	view data	-40 °C to  150 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.
A1242LUA-I2-T	3-pin SIP	Yes	view data	-40 °C to  150 °C		Due to warehouse relocation, samples will be unavailable until July 14, 2008. Contact your sales rep or purchase from distributor.

Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system.