September SA-V Single-Axis Magnetic Sensor ASIC Features: Sensitive to a magnetic field parallel with the chip surface Very high magnetic sensitivity Analog and digital output voltages Very low offset and offset-drift Very low noise Gain and offset programming Applications: Low Magnetic Field Measurement Contactless Distance Measurement DC to khz Current Sensing Magnetic Proximity Switch General Description The SA-V is a single-axis integrated magnetic field sensor based on the Hall effect. The circuit is fabricated using a conventional CMOS technology with an additional ferromagnetic layer. The ferromagnetic layer is used as a magnetic flux concentrator providing a high magnetic gain. Therefore, the circuit features very high magnetic sensitivity, low offset, and low noise. Moreover, the magnetic sensitivity, the residual offset, and their temperature coefficients can be altered by programming. The sensor SA-V provides two output signals: one is a precise analog voltage directly proportional to the magnetic field; the other is a digital signal being switched-on or switched-off at the presence of a sufficient magnetic field. The V-version of the SA- is optimized for applications where a high saturation limit of the measured field is required. During the manufacturing process or after customer installation, sensor parameters like sensitivity, offset and temperature coefficient can be one-time programmed. (Either programmed or unprogrammed sensors can be orderd.) Therefore, the circuit features a wide application range and very high accuracy. Page of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Package: SOIC-8 Pin Out: B. PV, programming voltage. GND. PD, programming data. PC, programming clock. D_OUT, digital output switch 6. CO_OUT, common output 7. A_OUT, analog output sensor 8. VDD Note: Also available in chip form Absolute Maximum Ratings Symbol Parameter Min. Typ. Max. Unit Remarks V SUP Supply Voltage 6 V V SUP T Ambient Temperature - + o C T Recommended Operating Conditions Symbol Parameter Min. Typ. Max. Unit Remarks V SUP Supply Voltage.. V I OUT Output Current - ma I Dout Output Current Switch ma Magnetic Switch C L Load Capacitance pf Electrical Characteristics At T=- C to C, VSUP=.V to.v if not otherwise specified. Symbol Parameter Min. Typ. Max. Unit Test Conditions I SUP Supply Current 6 ma V Common Common (reference) V SUP / V SUP / V SUP / I OUT =ma Output Voltage ) -mv +mv BW Bandwidth: DC to khz ) Ratiometric Page of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Characteristics of the Linear Magnetic Field Sensor With V SUP = V and in the temperature range - o C to o C, if not otherwise specified. I =ma Symbol Parameter Min. Typ. Max. Unit Test Conditions S Magnetic G= 8 Sensitivity,) G= 6 V/T S/S T Magn. Sensitivity -.. %/ C Temperature Drift ) OUT T=- C to C Voff Offset Voltage,) - mv B=T, Iout=mA, T= C, S=V/T Boff Equivalent Magnetic Offset,6) - µt B=T, I OUT =ma T=- C to 8 C Voff/ T Offset Temperature Drift -.. mv/ C B=T, I OUT =ma, T=- C to C S=V/T B FS Full Scale Magnetic Field Range - -7. 7. mt S=V/T S=V/T B L Linear Magnetic Field Range - - mt S=V/T S=V/T NL Non Linearity.. B=+/-mT %. B=+/-mT Bnoise Input referred magnetic noise spectrum density (RMS) nt/ Hz f=hz to khz ) Ratiometric (proportional to V SUP ) ) Programmable in 6 steps of about.v/t between G= and G= ) Programmable in 7 steps of about. %/ C ) Programmable in steps of mv (@G=) 6) Programmable in steps of about µt (@G=) Magnetic Characteristics of the Magnetic Switch 7) With V SUP =V and in the temperature range - o C to o C, if not otherwise specified. Symbol Parameter Min. Typ. Max. Unit Test Conditions B OP Magnetic Threshold Turn-On 8,9)... mt T= o C S=V/T B RP Magnetic Threshold Turn-Off 8,9) -. -. -. mt T= o C S=V/T B OP - B RP Hysteresis 8,9)...6 mt T= o C 7) When the digital output pin is used 8) Increases up to the factor of by decreasing the magnetic sensitivity 9) Ratiometric (proportional to V SUP ) Page of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Block Diagram VDD Hall Element System Offset Cancellation Amplifier Buffer & Filter A_OUT analog (differential) Schmitt Trigger CO_OUT D_OUT digital (single ended) Biasing Unit Programming Unit GND PV PC PD Hysteresis of Magnetic Switch (S=V/T) Hysteresis of Magnetic Switch output voltage magnetic switch [V]... B RP = -.mt B OP =.mt... -. - -. - -... Turn On Turn Off magnetic field [mt] Page of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Package Information SOIC-8 B: Magnetic sensitive direction B Dimension and Pads SA- in dice form (all dimensions in µm) 9 VDD 9 B A_OUT PV GND PD PC D_OUT CO_OUT Page of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Programming the Sensor Parameters This is an overview of the programming capabilities of the SA- sensor. For detailed information, please read the document Programming Instruction SA- with examples and supporting info. Sensitivity According to the application specific magnetic field strength, the sensitivity of the SA- can be programmed and ranges from S= to S=V/T (Gain= to ) by 6 Bits. Field B [mt] Sensitivity [V/T] Gain < < * for B >mt the sensor output becomes less linear, but the sensor can still be used Offset Compensation Sensor and application offsets such as mechanical and geometrical tolerances can be compensated by programming. Programmable Offset Compensation is performed by Bits in mv steps. Temperature Coefficient Sensor and application temperature drifts can be compensated by programming. Programmable Temperature Coefficient ranges from ppm/k to ppm/k in steps of ppm/k by Bits. Page 6 of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88
September Typical Applications. Angular Position Sensing using a Multipole Magnet S N S N The SA- is mounted in the vicinity outside a multipole magnet rotating on an axis. If the distance between magnet and chip center is about the pole distance on the magnet, then the SA- yields a sine-shape signal, which is transformed into a rectangular pulse signal by the digital output. Analog Output [V] Analog Output 6 9 8 Angle [ ] Digital Output [V] 6 - Digital Output 6 9 8 Angle [ ]. Position Switch using a Dipole Magnet Displacement The SA- is mounted underneath a small dipole magnet with its magnetization axis perpendicular to the chip surface. When the magnet moves along a line parallel to the axis of sensitivity of the SA-, the analog output of the SA- changes its sign. The digital output is V on one side an V on the other. Around the center the digital output shows a hysteresis between Bop and Brp of about. mt which (for the given example) corresponds to a mechanical hysteresis of about.mm. Analog Output [V] Analog Output... -. - -. - -. - - Displacement [mm] Digital Output [V]...... -. Digital Output - - Displacement [mm] Digital Output [V] Switching Hystere sis....... -.. -. -. -. -. -. -. -...... Displacement [mm] Analog Output [V] Page 7 of 7 Sentron AG Baarerstrasse 7 6 Zug Switzerland Phone: + () 7 7 Fax: + () 7 88