Datasheet

HMC1051/HMC1052/HMC1053
www.honeywell.com 11
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.
HMC1052
U1
Vcc
offset
set/reset
.1uf
IRF7509
set/reset
Vcc/2
Vcc/2
5.00k
5.00k
500k
500k
5.00k
5.00k
500k
500k
LMV324
LMV324
1nf
1nf
U3
U4
3.3 to 5.0v
HMC1051
U2
Vcc
Vcc/2
5.00k
5.00k
500k
500k
LMV324
.1µf
+
-
set/reset
µC
with
Multiplexed
A/D Conv.
AN0
AN1
AN2
AN3
Vcc/2
U6
U5
xout
yout
Two-axis
accelerometer
Vcc
Vcc
DO0
DI0
DI1
HMC1052
U1
Vcc
offset
set/reset
.1uf
IRF7509
set/reset
Vcc/2
Vcc/2
5.00k
5.00k
500k
500k
5.00k
5.00k
500k
500k
LMV324
LMV324
1nf
1nf
U3
U4
3.3 to 5.0v
HMC1051
U2
Vcc
Vcc/2
5.00k
5.00k
500k
500k
LMV324
.1µf
+
-
set/reset
µC
with
Multiplexed
A/D Conv.
AN0
AN1
AN2
AN3
Vcc/2
U6
U5
xout
yout
Two-axis
accelerometer
Vcc
Vcc
DO0
DI0
DI1
Figure 7
Three Axis Compass
MMBT2907ALT1
µC
To Sensor Circuits
toggle
10kΩ
+
-
10µf
0.01µf
Vcc
Vcc
Gnd
Off
On
*MMBD7001LT1
* Used when Vcc = 5.0 volts, jumper
when using Vcc = 3.3 volts or less.
MMBT2907ALT1
µC
To Sensor Circuits
toggle
10kΩ
+
-
10µf
0.01µf
Vcc
Vcc
Gnd
Off
On
*MMBD7001LT1
* Used when Vcc = 5.0 volts, jumper
when using Vcc = 3.3 volts or less.
Figure 8
Duty Cycling