Hall vs Temperature Sensors: Sensing Selection for Embedded Designs

1. Two sensing jobs

A Hall sensor converts a magnetic field into a switch or analog signal — used for position, rotation, lid detection and current sensing. A temperature sensor converts heat into resistance (NTC/PTC) or a digital/analog voltage (IC sensor) — used for protection, compensation and thermal management.

2. Hall sensor types

Type	Behaviour	Typical use
Switch (unipolar)	output changes when field exceeds Bop	lid, door, magnet detection
Latch	holds state until opposite pole seen	rotation / RPM counting
Linear	analog output proportional to field	position, current sensing

• Hysteresis (B_op − B_rp) prevents chatter — pick a part with enough for your magnet speed
• Open-drain outputs need a pull-up; check the sink current
• Supply 3.3 V or 5 V; keep the magnet field above B_op with margin at the worst air gap

3. Temperature sensor types

Type	Output	Accuracy / notes
NTC thermistor	resistance	±1–3% typical; B value 3380–3950 K; non-linear
PTC thermistor	resistance jump	self-protection / heating
IC sensor (analog)	voltage (e.g. 10 mV/°C)	±0.5–2°C
IC sensor (digital)	I²C / SPI	±0.5°C, addressable

NTC is cheap and fast but needs linearisation (Steinhart–Hart or a lookup table). An IC sensor costs more but gives a calibrated digital reading with no firmware curve fitting.

4. How to choose

• Magnetic position / rotation / current → Hall
• Thermal protection or compensation → NTC or IC temperature sensor
• Need a calibrated digital value with no linearisation → I²C IC sensor
• Cost-sensitive and space-limited → NTC with a lookup table

5. Design checks

• Place the sensor where it sees the real quantity — not next to a heat source it is meant to ignore
• Check the operating temperature range covers your worst case
• Filter the analog output before the ADC
• For Hall current sensing, keep the conductor geometry consistent

Related products

• Hall Sensor Series
• Temperature Sensor Series
• Thermistor Series
• Optocoupler Series