[AK8778] AK8778 Hall Effect IC for Pulse Encoders Overview The AK8778 is a Hall effect latch which detects both “vertical magnetic field” and “horizontal magnetic field” (perpendicular and parallel to the marking side of the package) at the same time. The pulse output F and direction output D are switched according to the vertical and horizontal magnetic fields applied to the device. The direction is calculated internally and output D is switched at a rising or falling edge of output F. The AK8778 is for use in the incremental pulse encoders or rotational detection systems. Features 4.0 to 24V supply voltage operation Low power consumption : 1.4mA(Typ.) Sensitivity (Vertical, Horizontal) : ±2.5mT(Typ.) Two outputs : F (Pulse), D (Direction) Small package: SOP-6pin Halogen free MS1467-E-00 September 2012 1 [AK8778] Block Diagram VDD 0.1mF REGULATOR VSS BIAS OSC HE_DRIVE TIMING LOGIC VREG COMP CHOP_AMP LATCH & LOGIC CHOPPER_SW F D HALL SENSORS Figure 1. Block diagram Circuit Configuration Table 1. Circuit configuration Block REGULATOR HALL SENSORS CHOPPER_SW CHOP_AMP COMP BIAS HE_DRIVE OSC TIMING LOGIC LATCH & LOGIC Function Generate internal operating voltage. Two Hall elements fabricated by CMOS process. Perform chopping in order to cancel the offset of Hall sensor. Amplifies two Hall sensor output voltage with summation and subtraction circuit. Hysteresis comparator. Generates bias current to internal circuits. Generates bias current for Hall sensors. Generates operating clock. Generates timing signal for internal circuits. Logical circuits and open drain driver. MS1467-E-00 September 2012 2 [AK8778] Pin/Function Table 2. Description of pin name and function Pin No. Pin name I/O Function 1 VDD Power supply pin 2 TAB (TAB pin) 3 F O Output F (Pulse) pin 4 D O Output D (Direction) pin 5 TAB (TAB pin) 6 VSS Ground pin Note) TAB pins should be connected to VSS. Note Open drain Open drain Absolute Maximum Ratings Table 3. Absolute maximum ratings Parameter Symbol Min. Max. Unit +32 Supply voltage VDD V 0.3 Output voltage VOUT +32 V 0.3 Output current ISINK 20 mA +150 Storage temperature TSTG 55 C Note) Stress beyond these listed values may cause permanent damage to the device. Note VSS=0V F,D pin VSS=0V F,D pin Recommended Operating Conditions Parameter Supply voltage Output current Operating temperature Table 4. Recommended operating conditions Symbol Min. Typ. VDD 4.0 12.0 ISINK Ta 40 MS1467-E-00 Max. 24.0 15 +115 Unit V mA C September 2012 3 [AK8778] Electrical Characteristics Table 5. Electrical characteristics at VDD=4.0 to 24.0V, Ta= 40 to +115C Parameter Symbol Min. Typ. Max. Unit Note Current consumption IDD 0.7 1.4 2.5 mA Average Output saturation voltage VSAT 0.4 V F, D pin, ISINK= 15mA Output leak current ILEAK 10 F, D=VDD mA 48.8 Pulse drive period TPD1 24.4 97.6 ms 24.4 Pulse drive duration time TPD2 12.2 48.8 ms Magnetic Characteristics Table 6. Magnetic characteristics at VDD=4.0 to 24.0V, Ta= 40 to +115C Parameter Symbol Operating point of BopV vertical magnetic field Releasing point of BrpV vertical magnetic field Operating point of BopH horizontal magnetic field Operating point of BrpH horizontal magnetic field Hysteresis BhV, BhH (*1) Horizontal magnetic flux density is zero. Min. Typ. Max. Unit Note 0.1 2.5 6.0 mT (*1) 6.0 2.5 0.1 mT (*1) 0.1 2.5 6.0 mT (*2) 6.0 2.5 0.1 mT (*2) mT (*1), (*2) 5.0 (*2) Vertical magnetic flux density is zero. MS1467-E-00 September 2012 4 [AK8778] Operational Characteristics The internal signal A switches „Low‟ state when the magnetic field perpendicular to the marking side of the package exceeds BopV. When the magnetic field is reduced below BrpV, the internal signal A goes „High‟ state. Otherwise; that is, in case of the magnetic field strength is greater than BrpV and smaller than BopV; the internal signal A keeps its status. S Internal signal A Top(Marking) BhV BopV BrpV Bottom 0 N N S Figure 2. Switching behavior of the internal signal A when vertical magnetic field is applied The internal signal B switches „Low‟ state when the magnetic field parallel to the marking side of the package exceeds BopH. When the magnetic field is reduced below BrpH, the internal signal B goes „High‟ state. Otherwise; that is, in case of the magnetic field strength is greater than BrpH and smaller than BopH; the internal signal B keeps its status. Internal signal B Line Marking Top(Marking) VSS pin BhH S N BopH BrpH 0 N D pin S Bottom Figure 3. Switching behavior of the internal signal B when horizontal magnetic field is applied MS1467-E-00 September 2012 5 [AK8778] Behaviors of internal signal A,B and output signal F, D when a rotating magnetic field is applied on AK8778 F signal (Pulse) is correspond to the result of EX-OR operation of internal signal A and B. And signal D (Direction) is calculated by the state of internal signal A and B. Direction changed Direction changed BopV Vertical M.F.D. BrpV 0 t BopH Horizontal M.F.D. 0 t BrpH Supply voltage VDD 0 t Internal signal A (Vertical) t Internal signal B (Horizontal) t F (Pulse) 0 t D (Direction) 0 t Undefined (High or Low) Signal F, D is determined. Figure 4. Behaviors of internal signal A,B and signal F, D when a rotating magnetic field is applied on AK8778 *M.F.D. is Magnetic Flux Density. Note) Signal D is determined after one signal F pulse is sent out. The indeterminate output state appears only in the powering up of this device. MS1467-E-00 September 2012 6 [AK8778] Functional Timing IDD TPD1: 48.8μs(Typ.) TPD2: 24.4μs(Typ.) IDD ON: 2.8mA(Typ.) 0 t Vertical M.F.D. BopV 0 BrpV t Horizontal M.F.D. BopH 0 BrpH t Internal signal A (Vertical) t Internal signal B (Horizontal) t F (Pulse) 0 t Figure 5. Timing diagram *M.F.D. is Magnetic Flux Density. MS1467-E-00 September 2012 7 [AK8778] Direction changed Direction changed IDD 0 t M.F.D. Vertical M.F.D. Horizontal M.F.D. BopV,BopH 0 BrpV,BrpH t 11μs(Typ.) 11μs(Typ.) 11μs(Typ.) 11μs(Typ.) F (Pulse) 50%VDD 0 t 11μs(Typ.) 11μs(Typ.) D (Direction) 50%VDD 0 t Figure 6. Timing diagram (in detail) *M.F.D. is Magnetic Flux Density. Note 1) VDD=12.0V ,RL=10k, CL=20pF Note 2) Signal F and D are changed at the same time. MS1467-E-00 September 2012 8 [AK8778] Typical Characteristic Data (for reference) Figure 7. Temperature dependence of sensitivity Figure 8. Temperature dependence of current consumption MS1467-E-00 September 2012 9 [AK8778] Package 6 5 4 1 2 3 1:VDD 2:TAB 3:F 4:D 5:TAB 6:VSS Unit in mm Figure 9. Package dimensions Note 1) The center of the sensitive area is located within the 0.3mm circle. Note 2) Coplanarity: The differences between standoff of terminals are max. 0.1mm. Note 3) The sensor part is located 0.71mm(Typ.) from marking surface. Material of terminals： Cu alloy Material of plating for terminals： Sn 100％ Thickness of plating for terminals：10μm (Typ.) MS1467-E-00 September 2012 10 [AK8778] Marking Line Marking 6 5 4 Marking is performed by laser 8YWWL Product name ：8 (AK8778) ：YWWL Date code Y：Manufactured year WW：Manufactured week 1 2 3 L：Lot Figure 10. Marking Recommended External Circuit 10kΩ VDD Output (F) GND 5 4 Top View 1 2 3 VDD 10kΩ VDD 0.1μF 6 Output (D) Figure 11. Recommended external circuit MS1467-E-00 September 2012 11 [AK8778] IMPORTANT NOTICE These products and their specifications are subject to change without notice. When you consider any use or application of these products, please make inquiries the sales office of Asahi Kasei Microdevices Corporation (AKM) or authorized distributors as to current status of the products. Descriptions of external circuits, application circuits, software and other related information contained in this document are provided only to illustrate the operation and application examples of the semiconductor products. You are fully responsible for the incorporation of these external circuits, application circuits, software and other related information in the design of your equipments. AKM assumes no responsibility for any losses incurred by you or third parties arising from the use of these information herein. AKM assumes no liability for infringement of any patent, intellectual property, or other rights in the application or use of such information contained herein. Any export of these products, or devices or systems containing them, may require an export license or other official approval under the law and regulations of the country of export pertaining to customs and tariffs, currency exchange, or strategic materials. 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