HMR2300-D00-232 Honeywell, HMR2300-D00-232 Datasheet - Page 11

• Manufacturer Part Number: HMR2300-D00-232
• Manufacturer: Honeywell

Specifications of HMR2300-D00-232

• Lead Free Status / RoHS Status: Not Compliant

HMR2300
CIRCUIT DESCRIPTION
The HMR2200 Smart Digital Magnetometer contains all the basic sensors and electronics to provide digital indication
of magnetic field strength and direction. The HMR2300 has all three axis of magnetic sensors on the far end of the
printed circuit board, away from the J1 and J2 connector interfaces. The HMR2300 uses the circuit board mounting
holes or the enclosure surfaces as the reference mechanical directions. The complete HMR2300 PCB assembly
consists of a mother board, daughter board, and the 9-pin D-connector (J1).
The HMR2300 circuit starts with Honeywell HMC2003 3-Axis Magnetic Sensor Hybrid to provide X, Y, and Z axis
magnetic sensing of the earth’s field. The HMC2003 contains the AMR sensing bridge elements, a constant current
source bridge supply, three precision instrumentation amplifiers, and factory hand-selected trim resistors optimized
for performance for magnetic field gain and offset. The HMC2003 is a daughter board that plugs into the HMC2300
motherboard, and the hybrid analog voltages from each axis is into analog multiplexors and then into three 16-bit
Analog to Digital Converters (ADCs) for digitization. No calibration is necessary as the HMC2003 hybrid contains all
the compensation for the sensors, and the set/reset routine handles the temperature drift corrections. A
microcontroller integrated circuit receives the digitized magnetic field values (readings) by periodically querying the
ADCs and performs any offset corrections. This microcontroller also performs the external serial data interface and
other housekeeping functions. An onboard EEPROM integrated circuit is employed to retain necessary setup
variables for best performance.
The power supply for the HMR2300 circuit is regulated +5 volt design (LM2931M) with series polarity power inputs
diodes in case of accidental polarity reversal. A charge pump circuit is used to boost the regulated voltage for the
set/reset pulse function going to the set/reset straps onboard the HMC2003. Transient protection absorbers are
placed on the TD, RD, and V+ connections to J1.
APPLICATIONS PRECAUTIONS
Several precautions should be observed when using magnetometers in general:
NON-FERROUS MATERIALS
Materials that do not affect surrounding magnetic fields are: copper, brass, gold, aluminum, some stainless steels,
silver, tin, silicon, and most non-metals.
HANDLING PRECAUTIONS
The HMR2300 Smart Digital Magnetometer measures fields within 2 gauss in magnitude with better than 0.1 milli-
gauss resolution. Computer floppy disks (diskettes) store data with field strengths of approximately 10 gauss. This
means that the HMR2300 is many times more sensitive than common floppy disks. Please treat the magnetometer
with at least the same caution as your diskettes by avoiding motors, CRT video monitors, and magnets. Even though
the loss of performance is recoverable, these magnetic sources will interfere with measurements.
Solid State Electronics Center • www.magneticsensors.com • [phone] • Page 11
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The presence of ferrous materials, such as nickel, iron, steel, and cobalt near the magnetometer will create
disturbances in the earth’s magnetic field that will distort the X, Y, and Z field measurements.
The presence of the earth’s magnetic field must be taken into account when measuring other magnetic
fields.
The variance of the earth’s magnetic field must be accounted for in different parts of the world. Differences in
the earth’s field are quite dramatic between North America, South America and the Equator region.
Perming effects on the HMR2300 circuit board need to be taken into account. If the HMR2300 is exposed to
fields greater than 10 gauss, then it is recommended that the enclosure/circuit boards be degaussed for
highest sensitivity and resolution. A possible result of perming is a high zero-field output indication that
exceeds specification limits. Degaussing wands are readily available from local electronics tool suppliers and
are inexpensive. Severe field offset values could result if not degaussed.
SENSOR PRODUCTS