Dual-channel quadrature Hall-effect bipolar switch is ultra-sensitive

Paul Boughton

Allegro Microsystems Europe is launching the A1230 ultra-sensitive dual-channel quadrature Hall-effect bipolar switch integrated circuit (IC) that is designed for use in rotating ring-magnet-based speed and direction sensing applications in harsh automotive and industrial environments.
The A1230 is a highly sensitive, temperature-stable magnetic sensing device incorporating two Hall-effect sensing elements spaced 1mm apart, each providing a separate digital output for speed and direction signal processing. The digital outputs are out of phase so that the outputs are in quadrature when interfaced with the proper ring-magnet design, allowing easy processing of the speed and direction signals.
Allegro Microsystems says that the two Hall elements are photolithographically aligned to better than 1um; the company claims that this accuracy has not previously been achieved in fine-pitch detection applications. Extremely low-drift amplifiers guarantee symmetry between the switches to maintain signal quadrature. Allegro's patented high-frequency chopper-stabilisation technique cancels offsets in each channel, thereby providing stable operation over the full specified temperature and voltage ranges.
The high-frequency chopping circuits also allow an increased analogue signal-to-noise ratio at the input of the digital comparators within the IC. As a result, the A1230 is claimed to achieve industry-leading digital output jitter performance that is important for high-performance motor commutation applications.
An on-chip low dropout (LDO) regulator enables the A1230 to be used over a wide operating voltage range. Post-assembly factory programming at Allegro provides sensitive switchpoints that are symmetrical between the two switches.
In addition, the A1230 features integrated electrostatic discharge protection between outputs and supply voltage to ground, a robust structure for EMC protection, and reverse battery protection on supply and both output pins.
The A1230 is available in a plastic eight-pin SOIC surface-mount package (L) and a plastic four-pin SIP (K). Both are available in a temperature range of -40 to +150 degrees C. Each package is lead-free, with a 100 per cent matt tin-plated leadframe.
For more information, visit www.allegromicro.com