AS5304

A S5304 / AS5306 Integrated Hall ICs for Linear and Off-Axis Rotary Motion Detection P RELIMINARY DATA S HEET 1 G eneral Description 2 • • • • B enefits C omplete system-on-chip H igh reliability due to non-contact sensing S uitable for the use in harsh environments R obust against external magnetic stray fields T he AS5304/AS5306 are single-chip IC’s with integrated Hall elements for measuring linear or rotary motion using multi-pole magnetic strips or rings. This allows the usage of the AS5304/AS5306 in applications where the Sensor IC cannot be mounted at the end of a rotating device (e.g. at hollow shafts). Instead, the AS5304/AS5306 are mounted off-axis underneath a multipole magnetized ring or strip and provides a quadrature incremental output with 40 pulses per pole period at speeds of up to 20 meters/sec (AS5304) or 12 meters/sec (AS5306). A single index pulse is generated once for every pole pair at the Index output. Using, for example, a 32pole-pair magnetic ring, the AS5304/AS5306 can provide a resolution of 1280 pulses/rev, which is equivalent to 5120 positions/rev or 12.3bit. The maximum speed at this configuration is 9375 rpm. The pole pair length is 4mm (2mm north pole / 2mm south pole) for the AS5304, and 2.4mm (1.2mm north pole / 1.2mm south pole) for the AS5306. The chip accepts a magnetic field strength down to 5mT (peak). Both chips are available with p ush-pull outputs (AS530xA) o r with o pen drain outputs (AS530xB) . The AS5304/AS5306 are available in a small 20-pin TSSOP package and specified for an operating ambient temperature of -40° to +125°C. 3 • • • • • • • • • K ey Features H igh speed, up to 20m/s (AS5304) 12m/s (AS5306) M agnetic pole pair length: 4 mm (AS5304) o r 2 .4mm (AS5306) R esolution: 2 5µm (AS5304) o r 1 5µm (AS5306) 4 0 pulses / 160 positions per magnetic period. 1 i ndex pulse per pole pair L inear movement magnetic strips measurement using multi-pole C ircular off-axis movement measurement using multipole magnetic rings 4 .5 to 5.5V operating voltage M agnetic field strength indicator, magnetic field alarm for end-of-strip or missing magnet 4 A pplications T he AS5304/AS5306 are ideal for high speed linear motion and off-axis rotation measurement in applications such as • • • • e lectrical motors X -Y-stages r otation knobs i ndustrial drives F igure 1: R evision 1.5 AS5304 (AS5306) with multi-pole ring magnet. F igure 2: AS5306 (AS5304) with magnetic multi-pole strip magnet for linear motion measurement P age 1 of 13 www.austriamicrosystems.com A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection 5 F unctional Description T he AS5304/AS5306 require a multi-pole magnetic strip or ring with a pole length of 2mm (4mm pole pair length) on the AS5304, and a pole length of 1.2mm (2.4mm pole pair length) on the AS5306. The magnetic field strength of the multi-pole magnet should be in the range of 5 to 60mT at the chip surface. The Hall elements on the AS5304/AS5306 are arranged in a linear array. By moving the multi-pole magnet over the Hall array, a sinusoidal signal (SIN) is generated internally. With proper configuration of the Hall elements, a second 90° phase shifted sinusoidal signal (COS) is obtained. Using an interpolation circuit, the length of a pole pair is divided into 160 positions and further decoded into 40 quadrature pulses. An Automatic Gain Control provides a large dynamic input range of the magnetic field. An Analog output pin (AO) provides an analog voltage that changes with the strength of the magnetic field (see chapter 8). F igure 3: AS5304 / AS5306 block diagram 6 S ensor Placement in Package T SSOP20 / 0.65mm pin pitch Die C/L 1.02 0.2299±0.100 0.2341±0.100 3.200±0.235 Package Outline 0.7701±0.150 3.0475±0.235 F igure 4: Sensor in package D ie Tilt Tolerance ±1º Revision 1.5 www.austriamicrosystems.com P age 2 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection 6 .1 P in Description P in P in Name P in Type N otes 1 2 3 4 5 ,12,13, 14,17,18,19 6 7 8 9 ,10,11 15 16 20 P IN Types: V SS A V DDP B TEST AO V DD I ndex TEST TEST_GND VDDA Hall ZPZmskdis S AIO DO_OD S D O_OD S D O_OD AIO AO S D O_OD AIO S S DI S upply ground I ncremental quadrature position output A. Short circuit current limitation Peripheral supply pin, connect to VDD I ncremental quadrature position output B. Short Circuit Current Limitation test pins, must be left open A GC Analogue Output. (Used to detect low magnetic field strength) P ositive supply pin I ndex output, active HIGH. Short Circuit Current Limitation test pins, must be left open test pin, must be connected to VSS Hall Bias Supply Support (connected to VDD) Test input, connect to VSS during operation supply pin AO analogue output analog input / output DI digital input digital output push pull or open drain (programmable) 6 .2 P ackage Drawings and Markings 2 0 Lead Thin Shrink Small Outline Package – T SSOP20 Revision 1.5 www.austriamicrosystems.com P age 3 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection D imensions S ymbol A A1 A2 b c D E E1 e K L 0° 0 .45 4.30 mm M in 0.05 0.80 0 .19 0 .09 6 .40 T yp 1.00 6.50 6 .40 4.40 0 .65 0.60 8° 0.75 0° 0.018 4.50 0.169 M ax 1 .20 0.15 1.05 0.30 0.20 6.60 M in 0.002 0.031 0.007 0.004 0.252 i nch T yp 0.039 0.256 0.252 0.173 0.0256 0.024 8° 0 .030 0 .177 M ax 0 .047 0 .006 0 .041 0 .012 0 .008 0 .260 M arking: AYWWIZZ A : Pb-Free Identifier Y: Last Digit of Manufacturing Year WW: Manufacturing Week I: Plant Identifier ZZ: Traceability Code JEDEC Package Outline Standard: M O-153-AC T hermal Resistance R th(j-a) : 89 K/W in still air, soldered on PCB. IC's marked with a white dot or the letters "ES" denote Engineering Samples 6 .3 E lectrical Connection T he supply pins VDD, VDDP and VDDA are connected to +5V. Pins VSS and TEST_GND are connected to the supply ground. A 100nF decoupling capacitor close to the device is recommended. F igure 5: Electrical connection of the AS5304/AS5306 Revision 1.5 www.austriamicrosystems.com P age 4 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection 7 I ncremental Quadrature AB Output S N S N S T he digital output is compatible to optical incremental encoder outputs. Direction of rotation is encoded into two signals A and B that are phase-shifted by 90º. Depending on the direction of rotation, A leads B (CW) or B leads A (CCW). 7 .1.1 I ndex Pulse 40 1 2 40 1 2 A 40 1 2 40 1 2 A s ingle index pulse is generated once for every pole pair. One pole pair is interpolated to 40 quadrature pulses (160 steps), so one index pulse is generated after every 40 quadrature pulses (see Figure 6) The Index output is switched to Index = high, when a magnet is placed over the Hall array as shown in Figure 7, top graph: the north pole of the magnet is placed over the left side of the IC (top view, pin#1 at bottom left) and the south pole is placed over the right side of the IC. The index output will switch back to Index = low, when the magnet is moved by one LSB from position X=0 to X=X1, as shown in Figure 7, bottom graph. One LSB is 25µm for AS5304 and 15µm for AS5306. N ote: Since the small step size of 1 LSB is hardly recognizable in a correctly scaled graph it is shown as an exaggerated step in the bottom graph of Figure 7 . B Index Detail: A B Index Step # 157 158 159 0 1 2 3 4 5 F igure 6: Quadrature A / B and Index output 7 .1.2 M agnetic Field Warning Indicator T he AS5304 can also provide a low magnetic field warning to indicate a missing magnet or when the end of the magnetic strip has been reached. This condition is indicated by using a combination of A, B and Index, that does not occur in normal operation: A low magnetic field is indicated with: Index = high A=B=low 7 .1.3 V ertical Distance between Magnet and IC T he recommended vertical distance between magnet and IC depends on the strength of the magnet and the length of the magnetic pole. Typically, the vertical distance between magnet and chip surface should not exceed ½ of the pole length. That means for AS5304, having a pole length of 2.0mm, the maximum vertical gap should be 1.0mm, For the AS5306, having a pole length of 1.2mm, the maximum vertical gap should be 0.6mm These figures refer to the chip surface. Given a typical distance of 0.2mm between chip surface and IC package surface, the recommended vertical distances between m agnet and IC surface a re therefore: AS 5304: ≤ 0 .8mm AS 5306: ≤ 0 .4mm Revision 1.5 www.austriamicrosystems.com P age 5 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection X=0 X Magnet drawn at index position X=0 CW magnet movement direction Hall Array Center Line N 4.220±0.235 S Index = High Pin 1 Chip Top view 3.0475±0.235 25µm (AS5304) 15µm (AS5306) X=0 X=X1 X Magnet drawn at position X1 (exaggerated) CW magnet movement direction Hall Array Center Line N 4.220±0.235 S Index = Low Pin 1 Chip Top view 3.0475±0.235 F igure 7: Magnet placement for index pulse generation 7 .1.4 S oft Stop Feature for Linear Movement Measurement W hen using long multi-pole strips, it may often be necessary to start from a defined home (or zero) position and obtain absolute position information by counting the steps from the defined home position. The AS5304/AS5306 provide a soft stop feature that eliminates the need for a separate electro-mechanical home position switch or an optical light barrier switch to indicate the home position. The magnetic field warning indicator (see 7.1.2) together with the index pulse can be used to indicate a unique home position on a magnetic strip: 1. 2. F irst the AS5304/AS5306 move to the end of the strip, until a magnetic field warning is displayed (Index = high, A=B=low) T hen, the AS5304/AS5306 move back towards the strip until the first index position is reached (note: an index position is generated once for every pole pair, it is indicated with: Index = high, A=B= high). Depending on the polarity of the strip magnet, the first index position may be generated when the end of the magnet strip only covers one half of the Hall array. This position is not recommended as a defined home position, as the accuracy of the AS5304/AS5306 are reduced as long as the multi-pole strip does not fully cover the Hall array. Revision 1.5 www.austriamicrosystems.com P age 6 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection 3. I t is therefore recommended to continue to the next (second) index position from the end of the strip (Index = high, A=B= high). This position can now be used as a defined home position. 7 .2 I ncremental Hysteresis I f the magnet is sitting right at the transition point between two steps, the noise in the system may cause the incremental outputs to jitter back and forth between these two steps, especially when the magnetic field is weak. To avoid this unwanted jitter, a hysteresis has been implemented. The hysteresis lies between 1 and 2 LSB, depending on device scattering. Figure 8 shows an example of 1LSB hysteresis: the horizontal axis is the lateral position of the magnet as it scans across the IC, the vertical axis is the change of the incremental outputs, as they step forward (blue line) with movement in +X direction and backward (red line) in –X direction. Note: 1LSB = 25µm for AS5304, 15µm for AS5306 I ncrem en tal o ut put X +4 X +3 X +2 X +1 H ys teres is: 1 LS B M agnet po sition X X X +1 X +2 X+ 3 X +4 M ov ement d ir ection: +X M ovem ent direc tion: -X F igure 8: Hysteresis of the incremental output 7 .3 I ntegral Non-Linearity (INL) T he INL (integral non-linearity) is the deviation between indicated position and actual position. It is better than 1LSB for both AS5304 and AS5306, assuming an ideal magnet. Pole length variations and imperfections of the magnet material, which lead to a non-sinusoidal magnetic field will attribute to additional linearity errors. 7 .3.1 E rror Caused by Pole Length Variations AS5304 Systematic Linearity Error caused by Pole Length Deviation 140 120 100 80 60 40 20 0 1500 Error [µm] F igure 9 and Figure 10 show the error caused by a non-ideal pole length of the multi-pole strip or ring. This is less of an issue with strip magnets, as they can be manufactured exactly to specification using the proper magnetization tooling. Error [µm] 1700 1900 2100 2300 2500 Pole Length [μm] F igure 9: Additional error caused by pole length variation: AS5304 AS5306 Systematic Linearity Error caused by Pole Length Deviation 140 120 100 80 60 40 20 0 900 1000 1100 1200 1300 Pole Length [μm] Error [µm] H owever, when using a ring magnet (see Figure 1) the pole length differs depending on the measurement radius. For optimum performance it is therefore essential to mount the IC such that the Hall sensors are exactly underneath the magnet at the radius where the pole length is 2.0mm (AS5304) or 1.2mm (AS5306), see also 8.1.2. Note that this is an additional error, which must be added to the intrinsic errors INL (see 7.3) and DNL (see 7.4). Error [µm] 1400 1500 F igure 10: Additional error caused by pole length variation: AS5306 Revision 1.5 www.austriamicrosystems.com P age 7 of 13 A S5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection 7 .4 D ynamic Non-Linearity (DNL) T he DNL (dynamic non-linearity) describes the non-linearity of the incremental outputs from one step to the next. In an ideal system, every change of the incremental outputs would occur after exactly one LSB (e.g. 25µm on AS5304). In practice however, this step size is not ideal, the output state will change after 1LSB +/-DNL. The DNL must be