The A139x family of linear Hall effect sensor integrated circuits from Allegro MicroSystems Europe combines micropower operation, a tri-state output and a user-selectable 'sleep' mode. The new sensor ICs provide a voltage output that is directly proportional to an applied magnetic field. The 'sleep' mode allows the devices to operate at a current consumption of less than 25 µA.
This low-current operation and the resulting power consumption of less than 10 mW makes these devices suitable for battery-operated applications such as mobile telephones, digital cameras, and portable tools. The operating voltage of 3 V makes them compatible with 2.5-3.5 V supplies. There are four devices in the family, differentiated only by sensitivity: A1391, 1.25 mV/Gs; A1392, 2.5 mV/Gs; A1393, 5 mV/Gs; and A1395, 10 mV/Gs. Despite the low power consumption of the circuitry in the A139x family, it offers the features required to produce a highly accurate linear Hall effect IC.
Each BiCMOS monolithic circuit integrates a Hall element, improved temperature-compensating circuitry to reduce the intrinsic sensitivity drift of the Hall element, a small-signal high-gain amplifier, and proprietary dynamic offset cancellation circuits. End-of-line post-packaging factory programming allows precise control of device sensitivity and offset. End users can control the current consumption of the A139x by applying a logic level signal to the 'sleep' pin. The outputs of the devices are not valid during sleep mode, when they switch to high-impedance mode. The high-impedance output feature allows the connection of multiple A139x Hall-effect devices to a single A-to-D convertor input.
The quiescent output voltage of these devices is 50% nominal of the ratiometric supply reference voltage applied to the reference pin of the device. The new sensors will operate over a wide ambient temperature range from -20°C to +85°C, and feature electrostatic discharge protection of greater than 3 kV. The A1391x Series devices are available in a small (2.0 × 3.0 mm, 0.75 mm nominal height) microleaded MLP/DFN package. The package is Pb (lead) free, with 100% matt tin leadframe plating.
