A3425

• Two matched Hall effect switches on a single substrate
• Sensor Hall element spacing approximately 1 mm
• Superior temperature stability
• 3.3 to 18 V operation
• Integrated ESD diode from OUTPUT and VCC pins to GND
• High-sensitivity switchpoints
• Robust structure for EMC protection
• Solid-state reliability

he A3425 is a dual-output channel, bipolar switch with two separate Hall-effect sensor circuits, each providing a separate digital output for speed and direction signal processing capability. Each sensor circuit has its own independent Hall element, which are photolithographically aligned to better than 1 µm. Maintaining accurate mechanical location between the two active Hall elements eliminates the major manufacturing hurdle encountered in fi ne-pitch detection applications. The A3425 is a highly sensitive, temperature-stable magnetic sensing device, which is ideal for use in ring magnet-based speed and direction systems used in harsh automotive and industrial environments.

The A3425 monolithic integrated circuit contains two independent Hall effect switches, located approximately 1 mm apart. The digital outputs are 90º out of phase so that the outputs are in quadrature with the proper ring magnet design. This allows for easy processing of speed and direction signals. Extremely low- drift amplifi ers guarantee symmetry between the switches to maintain signal quadrature. The patented chopper stabilization technique cancels offsets in each channel, and provides stable operation over the operating temperature and voltage ranges. An on-chip regulator allows the use of this device over a wide operating voltage range. Post-assembly factory programming provides sensitive switchpoints that are symmetrical between the two switches.