Features: Chopper stabilization
Low switchpoint drift over operating temperature range
Low sensitivity to stress
Factory programmed at end-of-line for optimized switchpoints
On-chip protection
Supply transient protection
Reverse-battery protection
On-board voltage regulator
3.5 to 24 V operation
SpecificationsSupply Voltage, VCC ..........................................28 V
Reverse-Supply Voltage, VRCC .......................18 V
Magnetic Flux Density, B .............................Unlimited
Power Dissipation, PD...............................Graph, p. 5
Operating Temperature
Ambient, TA, Range E..........................40ºC to 85ºC
Ambient, TA, Range L........................40ºC to 150ºC
Maximum Junction, TJ(max)...............................165ºC
Storage Temperature, TS ................65ºC to 170ºCDescriptionThe A1147 and A1148 devices are two-wire, unipolar, Hall effect switches that are factory-programmed at end-of-line to optimize ultrasensitive magnetic switchpoint accuracy. A1147 and A1148 use a patented high frequency chopper-stabilization technique, produced using the Allegro advanced BiCMOS wafer fabrication process, to achieve magnetic stability and to eliminate offset inherent in single-element devices exposed to harsh application environments.
Commonly found in a number of automotive applications, A1147 and A1148 are utilized to sense seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position. Two-wire unipolar switches, such as the A1147 and A1148, are particularly advantageous in price-sensitive applications because they require one less wire for operation than do switches with the more traditional open-collector output. Additionally, the system designer inherently gains diagnostics because there is always output current flowing, which should be in either of two narrow ranges. Any current level not within these ranges indicates a fault condition. A1147 and A1148 also feature on-chip transient protection and a Zener clamp to protect against overvoltage conditions on the supply line.
The output currents of the A1148 switches HIGH in the presence of a south (+) polarity magnetic field of sufficient strength, and switches LOW otherwise, as in the presence of a weak field or a north () polarity field. The A1147 has an opposite output: the currents switch LOW in the presence of a south-polarity magnetic field of sufficient strength, and switch HIGH otherwise.
Both versions are offered in two package styles. The LH is a SOT-23W, miniature low-profile package for surface-mount applications. The UA is a three-lead ultramini SIP for through-hole mounting. Each package is available in a lead (Pb) free version (suffix, T) with 100% matte tin plated leadframe. Field-programmable versions are also available: A1180 and A1181.
Also see: A1140-43 and A1145-46
A1148 Data Sheet
