HMC1023PCB HONEYWELL [Honeywell Solid State Electronics Center], HMC1023PCB Datasheet - Page 6

• Manufacturer Part Number: HMC1023PCB
• Description: 3-AXIS MAGNETIC SENSOR
• Manufacturer: HONEYWELL [Honeywell Solid State Electronics Center]

HMC1023
A reset pulse is defined as a negative pulse current entering the S/R+ strap connection. The successful result would
be the magnetic domains aligned in a reverse easy-axis direction so that sensor bridge’s polarity is a negative slope
with positive fields on the sensitive axis result in negative voltages across the bridge output connections.
Typically a reset pulse is sent first, followed by a set pulse
a few milliseconds later. By shoving the magnetic domains
in completely opposite directions, any prior magnetic
disturbances are likely to be completely erased by the duet
of
requirements for noise and accuracy, a single polarity
pulse circuit may be employed (all sets or all resets). With
these uni-polar pulses, several pulses together become
close in performance to a set/reset pulse circuit. Figure 1
shows a quick and dirty manual pulse circuit for uni-polar
application of pulses to the set/reset strap.
Application Notes
Three Axis Compassing with Tilt Compensation
For full three-axis compassing, the circuit depicted in Figure 2 shows HMC1023 used for sensing the magnetic field
in three axes. A two-axis accelerometer with digital (PWM) outputs is also shown to provide pitch and roll (tilt)
sensing, to correct the three-axis magnetic sensors outputs into to the tilt-compensated two-axis heading. The
accelerometer can be substituted with a fluidic 2-axis tilt sensor if desired. For lower voltage operation with Lithium
battery supplies (2.5 to 3.6Vdc), the Set/Reset circuit should be upgraded from a single IRF7509 to the dual IRF7509
implementation (H-bridge) to permit a minimum 1.5-ampere pulse (500mA per set/reset strap resistance) to the
sensors.
Solid State Electronics Center • www.magneticsensors.com • [phone] • Page 6
pulses.
For
simpler
Vcc
Vcc
Vcc
Vcc
U1
U1
circuits
HMC1023
HMC1023
set/reset
set/reset
U2
U2
with
.33uf
.33uf
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
5.00k
less
IRF7509
IRF7509
Three Axis Compass
500k
500k
500k
500k
500k
500k
1nf
1nf
1nf
1nf
.1 f
.1 f
critical
Vcc/2
Vcc/2
Vcc/2
Vcc/2
Vcc/2
Vcc/2
Figure 7
-
-
+
+
LMV324
LMV324
LMV324
LMV324
U4
U4
LMV324
LMV324
U3
U3
500k
500k
500k
500k
500k
500k
5 volts
5 volts
Vcc
Vcc
accelerometer
accelerometer
3.3 to 5.0v
3.3 to 5.0v
Two-axis
Two-axis
yout
yout
xout
xout
Set Pulse Circuit
Vcc/2
Vcc/2
U5
U5
Vcc
Vcc
set/reset
set/reset
Figure 1
DO0
DO0
AN0
AN0
AN1
AN1
AN2
AN2
AN3
AN3
DI0
DI0
DI1
DI1
Multiplexed
Multiplexed
A/D Conv.
A/D Conv.
with
with
U6
U6
SENSOR PRODUCTS
C
C
Iset
Iset
Rsr
Rsr
3.0
3.0