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Related Links:

Datasheets:
A1171: Micropower Ultrasensitive Hall Effect Switch (PDF)

Selection Guides:
Omnipolar Hall-Effect Digital Switches

when this product is updated

Press Releases:
A1171: Allegro MicroSystems, Inc. Introduces a New MicroPower Hall-Effect Switch with Complementary Push-Pull Outputs

A1171
Micropower Ultrasensitive Hall Effect Switch

Features

• 1.65 to 3.5 V battery operation
• Low supply current
• High sensitivity, B_OP typically 30 G (3.0 mT)
• Operation with either north or south pole
• Configurable unipolar or omnipolar magnetic sensing
• Complementary, push-pull outputs
• Chopper stabilized
  Superior temperature stability
  Extremely low switchpoint drift
  Insensitive to physical stress
• Solid state reliability
• Small size

Description

The A1171 integrated circuit is an ultrasensitive, Hall effect switch with latched digital outputs and either unipolar or omnipolar magnetic actuation. It features operation at low supply currents and voltages, making it ideal for battery-operated electronics. The low operating supply voltage, 1.65 to 3.5 V, and unique clocking algorithm assist in reducing the average operating power consumption. For example, the power requirement is less than 15 µW with a 2.75 V supply.

Unlike more traditional Hall effect switches, the A1171 allows the user to configure how the device is magnetically actuated. Under default conditions the device activates output switching with either a north or south polarity magnetic field of sufficient strength. The magnetic actuation can be set via an external selection pin to operate in a unipolar mode, switching only on a north or south polarity but not both. Furthermore, the output of the A1171 can be configured to switch either off or on in the absence of any significant magnetic field. Lastly, the A1171 has two push-pull output structures.

This polarity-independence, as well as the minimal power requirements, allows the A1171 to easily replace reed switches, providing superior reliability and ease of manufacturing while eliminating the requirement for signal conditioning.

Improved stability is made possible through dynamic offset cancellation using chopper stabilization, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. This device includes, on a single silicon chip, a Hall-voltage generator, a small-signal amplifier, chopper stabilization, a latch, and a MOSFET output.

The A1171 device offers a magnetically optimized solution, suitable for most applications. Package type EW (0.40 mm maximum height) offers a leadless surface mount solution. It is lead (Pb) free, with NiPdAu leadframe plating.

Functional Block Diagram

Complete Part Numbers

Part Number	Package Type	RoHS Compliant	Part Composition/ RoHS Data	Temperature	Comments	Samples	Distributor Stock
A1171EEWLT-P	6-lead MLP/DFN	Yes	view data	-40 °C to  85 °C	new

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.