HMC6052 Datasheet, PDF (5/6 Pages) List of Unclassifed Manufacturers – INTEGRATED COMPASS SENSOR

HMC6052
Reference Design
The schematic diagram in Figure 1 shows the basic HMC6052 application circuit with a minimum of external components.
Vdds = 3V
3 _VBRIDGE
AMR
GND
AMR
4 ^OFF-
NC
1 ^OFF+
NC
GND
OFFSET
SET
S/R+
6
SC-
5
V+
G
GND
V+
G
GND
V+
SW
GND
SC+
9
0.1µF X7R
(2)
XTAL0
OUTA 13
OUTB ₁₄
Vref
RS
11
V+
12
GND
8
VSR ₇
SINL
V+
SW
10
SINH
GND
GND
XTAL1
AN0
CLK
AN1
TXD
RXD
DO0
µP DO1
DO2
Vss
Vdd
GND _MMBT2907
SERIAL
I/O
Vdd
+3V
Vdds
GND
1µF X7R
+
10k Ω
GND
Figure 1
From Figure 1, the host microprocessor (µP) controls the HMC6052 via digital output port lines DO0 through DO2. The
first digital control line (DO0) is normally in a high logic state and briefly pulls down to drive the high-side switch connected
to pin 10 (SINH) of the HMC6052. Likewise, DO1 is a reverse logic control line that is normally low and pulls high briefly to
drive the low-side switch at pin 7 (SINL) of the HMC6052. Together DO0 and DO1 toggle states to create a “set” pulse
through the internal set strap resistance that spirals through the sensor bridge elements. This set pulse creates an intense
magnetic field that will re-align the magnetic domains of the magneto-resistive elements to undo the effects of thermal
agitation, and any magnetic upset events that might “disturb” the sensors. The frequency of the toggling is the designer’s
choice, but typically ranges from once per second to once per day. The external set strap capacitance across pins 5 (SC-)
and 9 (SC+) is to be around 0.2uf to 1uf in value, with emphasis on keeping the total capacitor ESR (effective series
resistance) below 0.5 ohms to minimize capacitor internal losses while delivering a current spike in excess of 0.5
amperes.
The microprocessor also has control of the complete power supplied to the HMC6052 via digital control line DO2 that
switches the MMBT2907 bipolar junction transistor, to connect the 3.0-volt system supply voltage to the sensor circuits.
By pulling low DO2, the transistor saturates to connect Vdd to Vdds, which are the switched supply connections to
VSUPPLY (pin 11) and VBRIDGE (pin 3). With power applied, the HMC6052 internal circuits quickly stabilize to provide
accurate magnetic vector voltages at output pins 13 (OUTA) and 14 (OUTB). With near zero magnetic field inputs, OUTA
and OUTB should be near half the supply voltage to provide bipolar output voltage values corresponding to the intensity
and polarity of the resulting magnetic fields on the sensor bridges. Zero field stimulus to the HMC6052 can be obtained
using magnetic shielded containers, or helmholtz coil sets.
Toggling the DO2 digital control line is necessary in many applications to reduce the total system current consumption
when not taking magnetic field measurements to preserve battery energy reserves. Up to 15mA can be drawn from the
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