Hall latch for speed and direction sensing
The TLV4946-2K is a Hall-effect latch from Infineon — it switches its open-drain output when a south-pole field crosses 3.5 mT and releases at -3.5 mT (north pole). The latch behaviour means the output stays high until the opposite polarity is applied, which suits brushless-DC motor commutation, rotary encoder index detection, and flow-meter pulse counting. Supply voltage is 2.7 V minimum, so it runs from a 3.3 V or 2.8 V rail without a regulator. The open-drain output sinks up to 20 mA, enough to drive a logic input or a small LED directly.
Temperature range and field threshold
Rated -40°C to 85°C, the TLV4946-2K covers industrial and automotive-cabin environments. The temperature-compensated design keeps the operate and release points stable across the range. Operate point is 3.5 mT (south pole), release is -3.5 mT (north pole). This hysteresis prevents chatter from electrical noise or mechanical vibration in the target magnet.
Sourcing and lifecycle status
Infineon lists the TLV4946-2K as Active. The silicon is in a standard surface-mount SOT-23 footprint — confirm the specific package code on the reel label when ordering.