HMC1055 datasheet(7/12 Pages) ETC1

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HMC1055

Advance Information

SENSOR PRODUCTS

MXS3334UL

Application Notes

The HMC1055 Chipset is composed of three sensors packaged as integrated circuits for tilt compensated electronic

compass development. These three sensors are composed of a Honeywell HMC1052 two-axis magnetic field sensor,

a Honeywell HMC1051Z one-axis magnetic sensor, and the Memsic MXS3334UL two-axis accelerometer.

Traditionally, compassing is done with a two-axis magnetic sensor held level (perpendicular to the gravitational axis)

to sense the horizontal vector components of the earth’s magnetic field from the south pole to the north pole. By

incorporating a third axis magnetic sensor and the two-axis accelerometer to measure pitch and roll (tilt), the compass

is able to be electronically “gimbaled” and can point to the north pole regardless of level.

The HMC1052 two-axis magnetic sensor contains two Anisotropic Magneto-Resistive (AMR) sensor elements in a

single MSOP-10 package. Each element is a full wheatstone bridge sensor that varies the resistance of the bridge

magneto-resistors in proportion to the vector magnetic field component on its sensitive axis. The two bridges on the

HMC1052 are orientated orthogonal to each other so that a two-dimensional representation of an magnetic field can

be measured. The bridges have a common positive bridge power supply connection (Vb); and with all the bridge

ground connections tied together, form the complete two-axis magnetic sensor. Each bridge has about an 1100-ohm

load resistance, so each bridge will draw several milli-amperes of current from typical digital power supplies. The

bridge output pins will present a differential output voltage in proportion to the exposed magnetic field strength and the

amount of voltage supply across the bridge. Because the total earth’s magnetic field strength is very small (~0.6

gauss), each bridge’s vector component of the earth’s field will even be smaller and yield only a couple milli-volts with

nominal bridge supply values. An instrumentation amplifier circuit; to interface with the differential bridge outputs, and

to amplify the sensor signal by hundreds of times, will then follow each bridge voltage output.

The HMC1051Z is an additional magnetic sensor in an 8-pin SIP package to place the sensor silicon die in a vertical

orientation relative to a Printed Circuit Board (PCB) position. By having the HMC1052 placed flat (horizontal) on the

PCB and the HMC1051Z vertical, all three vector components of the earth’s magnetic field (X, Y, and Z) are sensed.

By having the Z-axis component of the field, the electronic compass can be oriented arbitrarily; and with a tilt sensor,

perform tilt-compensated compass heading measurements as if the PCB where perfectly level.

Solid State Electronics Center

• www.magneticsensors.com • (800) 323-8295 • Page 7

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