HMC1051Z Honeywell, HMC1051Z Datasheet - Page 5

• Manufacturer Part Number: HMC1051Z
• Manufacturer: Honeywell

Specifications of HMC1051Z

• Lead Free Status / Rohs Status: Compliant

HMC1051Z / HMC1052
Set/Reset Circuit Notes
The set/reset circuit using the IRF7507 dual complementary MOSFETs is shown in Figure 2 with more detail in its H-
bridge driven configuration. This configuration is used primarily in battery operated applications were the 0.5 ampere
nominal set/reset pulsed currents are best obtained under low voltage conditions. For operation at normal 3.3 or 5
volt logic levels, a single complementary MOSFET pair can be used in a single ended circuit shown in Figure 3.
Other complementary MOSFET pairs can be used with the caution that the chosen devices should have less than
0.5 ohms ON resistance and be able to handle the needed supply voltages and set/reset currents. Note that even a
1Hz rate of set/reset function draws an average current of less than 2 microamperes.
Magnetic Field Detection
For simple magnetic field sensing applications such Magnetic Anomaly Detectors (MADs) and Magnetometers, a
similar circuit to the compass application can be implemented. In the example circuit in Figure 4, a HMC1051Z
sensor bridge is used with a low voltage capable dual op-amp to detect sufficient intensity of a magnetic field. Uses
of the circuit include ferrous object detection such as vehicle detection, a “sniffer” for moderate currents in nearby
conductors, and magnetic proximity switching. By using two circuits with a HMC1052, a more omni-directional
sensing pattern can implemented. There is nothing special in choosing the resistors for the differential op-amp gain
stages other than having like values (e.g. the two 5kΩ and the 500kΩ resistors) matched at 1% tolerance or better to
reject common-mode interference signals (EMI, RFI). The ratio of the 500kΩ/5kΩ resistors sets the stage gain and
can be optimized for a specific purpose. The choice of the 5kΩ value sets impedance loading seen by the sensor
bridge network and should be about 4 kilo-ohms or higher for best voltage transfer or matching.
Solid State Electronics Center • www.magneticsensors.com • [phone] • Page 5
Rset/reset
Figure 2
4Ω
.1µf
D
D
S
S
Vsr
IRF7509(P)
IRF7509(N)
1µf
G
G
+
-
D
D
S
S
Vsr
IRF7509(N)
IRF7509(P)
G
G
200Ω
set/reset
_set/reset
Vcc
Rset/reset
Figure 3
4Ω
.1µf
1µf
+
-
D
D
S
S
Vsr
IRF7509(P)
SENSOR PRODUCTS
IRF7509(N)
G
G
200Ω
set/reset
Vcc