HMC1051/HMC1052/HMC1053
U1
Vcc
1nf
500k
3.3 to 5.0v
Vcc
5.00k
AN0
AN1
AN2
AN3
LMV324
5.00k
U3
500k
Vcc/2
1nf
Vcc/2
HMC1052
set/reset
DO0
500k
5.00k
5.00k
U6
LMV324
500k
µC
Vcc/2
with
.1uf
U4
set/reset
Multiplexed
A/D Conv.
IRF7509
Vcc
offset
U5
set/reset
Two-axis
accelerometer
Vcc
.1µf
500k
U2
5.00k
5.00k
-
LMV324
xout
yout
DI0
DI1
+
500k
Vcc/2
HMC1051
Figure 7
Three Axis Compass
Duty Cycling for Lower Energy Consumption
For battery powered and other applications needing limited energy consumption, the sensor bridge and support
electronics can be switched “off” between magnetic field measurements. The HMC105X family of magnetic sensors are
very low capacitance (Bandwidth > 5MHz) sensor bridges and can stabilize quickly, typically before the support
electronics can. Other energy saving ideas would be to minimize the quantity of set/reset pulses which saves energy over
the battery life. Figure 8 shows a simple supply switching circuit that can be microprocessor controlled to duty cycle
(toggle) the electronics in moderate current (<25mA) applications.
Vcc
MMBT2907ALT1
To Sensor Circuits
Vcc
0.01µf
+
-
Gnd
10µf
µC
* Used when Vcc = 5.0 volts, jumper
when using Vcc = 3.3 volts or less.
*MMBD7001LT1
Off
On
toggle
10kΩ
Figure 8
Duty Cycling
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