CMOS Omnipolar High Sensitivity Micropower Hall SwitchFeatures¾ Micropower consumption for battery poweredapplications¾ Omnipolar, output switches with absolute value oNorth or South pole from magnet¾ Operation down to 2.5V¾ High sensitivity for direct reed switch replacement applicationsChopper stabilized amplifier stage2．DescriptionThe EST248 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 operatingill 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 transistor of the yh148 will be latched off (Brp) in the absence of a magnetic field.