HMC6343_13 Datasheet, PDF (6/13 Pages) Honeywell Solid State Electronics Center – 3-Axis Compass with Algorithms

HMC6343
BASIC DEVICE OPERATION
The Honeywell HMC6343 magnetoresistive sensor circuit is a trio of magnetic sensors, accelerometers, and analog
support circuits to measure magnetic fields. Additionally a microcontroller is integrated for computation of direction and
calibration. With power supply applied, the sensor converts any incident magnetic field in the sensitive axis direction to a
differential voltage output. In addition to the bridge circuit, the sensors have on-chip magnetically coupled offset straps for
incident field adjustment.
The circuit is sensitive to power supply noise, and adding a 1.0 microfarad ceramic capacitor is recommended on the
positive supply to help reduce noise. Also careful layout practices should be enforced to keep high current traces (>10mA)
a few millimeters away from the sensors. Also, since the sensors are typically sensing the earth’s magnetic field direction,
avoid employing RF/EMI shields using ferrous metals or coatings.
BASIC SCHEMATIC INTERFACE
HMC6343
VDD2 ²¹
VDD1 ³
VDD3 ¹¹
+3.3V
1uF
HOST
P
VDD
32
SCL
36
SDA
22
CS
35
CS_CTRL
25
GND2
29
GND1
10k 10k
I2C_CLK
I2C_DATA
GND
Offset Straps
The three offset straps have a spiral of metallization that couples in the sensor element’s sensitive axis. The straps will
handle currents to buck or boost fields through the ±4 gauss linear measurement range, but designers should note the
thermal heating on the die when doing so.
With most applications, the offset strap is not utilized and can be ignored. Designers can leave one or both strap
connections (Off- and Off+) open circuited, or ground one connection node.
Operational Modes
The HMC6343 has three operational modes; Sleep, Standby, and Run. Sleep mode is defined as having the analog
circuitry powered off, and has the lowest power consumption while power is applied to the VDD pins. Standby mode has
the HMC6343 fully powered, but with no measurements performed and the processor is waiting for commands to perform.
Run mode is fully engaged in continuous measurements at the set rate, and ready to receive further commands. The
operational mode settings are stored in EEPROM register 0x04, and shown further the HMC6343 protocol definition.
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