低功率霍尔元件DH471.doc

Features Micropower consumption for battery powered applications Omnipolar, output switches with absolute value of North or South pole from magnet Operation down to 2.5V High sensitivity for direct reed switch replacement applications CMOS output Chopper stabilized amplifier stage2．Description The DH471 Omnipolar Hall effect sensor IC is fabricated from mixed signal CMOS technology .It incorporates advanced chopper-stabilization techniques to provide accurate and stable magnetic switch points. The circuit design provides an internally controlled clocking mechanism to cycle power to the Hall element and analog signal processing circuits. This serves to place the high current-consuming portions of the circuit into a “Sleep” mode. Periodically the device is “Awakened” by this internal logic and the magnetic flux from the Hall element is evaluated against the predefined thresholds. If the flux density is above or below the Bop/Brp thresholds then the output transistor is driven to change states accordingly. While in the “Sleep” cycle the output transistor is latched in its previous state. The design has been optimized for service in applications requiring extended operating lifetime in battery powered systems. The output transistor of the DH471 will be latched on (Bop) in the presence of a sufficiently strong South or North magnetic field facing the marked side of the package. The output will be latched off (Brp) in the absence of a magnetic field. 3．Applications Solid state switch Handheld Wireless Handset Awake Switch Lid close sensor for battery powered devices Magnet proximity sensor for reed switch replacement in low duty cycle applications 4．Typical Application Circuit Innosens pole-independent sensing technique allows for operation with either a north pole or south pole magnet orientation, enhancing the manufacturability of the device. The state-of-the-art technology provides the same output polarity for either pole face. It is strongly recommended that an exter