Improved Speed and Direction Sensing Using Vertical Hall Technology

Improved Speed and Direction Sensing Using Vertical Hall Technology

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By Marvin Ng, Allegro MicroSystems, LLC

Introduction

这A12622 d双通道采用霍尔传感器集成电路offered in a 5-pin SOT23W surface-mount package, as well as a 4-pin SIP through-hole package. It features operation with traditional planar—as well as vertical—magnetic field direction. The dual operation of the centrally located planar and vertical Hall elements results in:

• Inherent 90° phase separation between outputs (quadrature), making quadrature magnet pole-pitch and air gap independent
• Smaller package size, allowing smaller PCB size and tighter Total Effective Air Gap (TEAG)
• X-Z选项提供更小的尺寸传感Teagg
• 机械设计的灵活性利用自由选择环形磁铁基于可用性和/或成本
• A potential replacement of through-hole devices, as in-plane sensing can be achieved with an SMT device

这two available options allow system design flexibility by sensing in the Y and Z axes or the X and Z axes. This allows the sensor IC, and therefore the PCB on which it is mounted, the flexibility to be mounted in different orientations, relative to the magnet.

A1262是先前一代装置的替代解决方案，例如A1230和A3425，其1D（双平面厅）设计需要环形磁极间距优化并仅提供一种感测方向，而A1262不需要环形磁铁优化和罐头配置为四种不同的方向（请参阅感应配置部分）。另外，A1262以较小的（SOT23W）包装提供。有关2D A1262至双平面A1230和A3425的比较，请参见表1。

Table 1: Comparison of 2D versus 1D (Dual Planar)

Characteristic	Device
	A1262	A1230	A3425
Hall Element Spacing	n/a	1.0 mm	1.0 mm
Inherent Output Quadrature	Yes	No	No
传感配置	4.	1	1
Available Packages	LH (SOT23W), K (SIP)	L (SOIC), K (SIP)	L (SOIC), K (SIP)
BOP / BRP (maximum)	±40 g	±30 G	±30 G
Output Polarity, B > BOP	Low	Low	Low

Vertical and Planar Hall Elements

Advances in IC design and fabrication allow the creation of vertical Hall elements sensitive to magnetic fields parallel to the plane of the IC. They function under the same principles of planar Hall elements, which are sensitive only to magnetic fields perpendicular to the plane of the IC. This Z-axis sensitivity is not altered by the
sensor IC orientation or rotation. As such, in-plane sensing is not possible using a surface-mount device with only a planar Hall element.

Planar Hall elements are constructed across the length and width of the die (in-plane) as shown in Figure 2. Vertical Hall elements are constructed from bottom to top along the depth of the chip as shown in Figure 3.

By rotating the IC, or by altering the orientation of the vertical Hall sensing elements on the die, a sensor IC can discriminate magnetic field direction as well as amplitude and truly sense in multiple spatial dimensions. In the A1262, the X and Y axes are the vertical Hall sensing axes, and the Z axis is the planar Hall sensing axis (See Figure 4).

A1262有两个不同的传感配置，可以选择作为订购选项。差异是垂直霍尔元素的方向。X-Z选项在X轴上定向有一个垂直的霍尔元素，与Z轴中的平面厅元件一起工作。Y-Z选项的垂直霍尔元件旋转以在Y轴上敏感。这允许用户选择如何相对于环形磁铁定位传感器IC。这在感测配置部分中进一步解释。

传感配置

A1262提供双通道感应，具有环形磁磁型输出正交。提供两种不同的2D感测轴配置，X-Z和Y-Z轴。垂直和平面霍尔元素一起使用以产生正交输出，类似于使用类似A1230或A3425的双平面传感器IC（但是，双平面图传感器仅在一个配置中敏感）。Planar Hall Element定位在环形磁体上的磁极感测磁极，而垂直霍尔元件感测过磁极之间的过渡（如图12所示）。

In the X-Z configuration (Figure 5), the Hall elements are positioned to detect magnetic fields parallel to the face of the package, across/perpendicular to the non-leaded sides (X axis) and magnetic fields perpendicular to the face of the package (Z axis), as shown in Figure 2. The vertical Hall can be configured to sense the magnet poles (head-on).

Since the sensor IC is sensitive on the edges without leads, the IC can be positioned closer to the target (compared to the Y-Z combination), in applications which require the IC to be oriented with the vertical element positioned head-on to the magnet (see Figure 7).

In the Y-Z configuration (Figure 6), the Hall elements are positioned to detect magnetic fields parallel to the face of the package across the leaded sides (Y-axis) and magnetic fields perpendicular to the face of the package (Z-axis). The vertical Hall can be configured to sense the magnet poles (head-on). Traditional dualchannel devices like the A1230 and A3425 cannot sense the ring magnet in either of the Figure 6 configurations (A or B).

关闭气隙能力

可用的X-Z选项允许传感器的极其紧密的空气间隙定位到磁体上，以进行需要PCB垂直于环形磁体的应用。亚博尊贵会员这是由于敏感边缘是没有引线的侧面。

Figure 7 illustrates the advantage of sensing on the side without leads. Sensing on the leadless sides allows the IC to be placed at the edge of the PCB, without the need to accommodate the device leads and the associated PCB solder pads and traces. This results in a significant reduction in Total Effective Air Gap (TEAG). On the Y-Z option the sensor must be placed further inboard on the PCB.

Table 2: Sensing Option Part Numbers

Y-Z Option	X-Z Option
A1262LLH-T	A1262LLH-X-T

双重输出

这A1262 is a dual-output sensor with outputs for the vertical Hall element (X or Y) and planar Hall element (Z) on two independent output pins (OUTPUTA and OUTPUTB, respectively). This is achieved with time-division multiplexing of the channels. See the block diagram in Figure 8. Each channel is sampled approximately every 16 μs (typical) to allow for channel settling, therefore both channels are updated approximately every 32 μs. See Figure 9.

这relatively fast time-division multiplexing of the A1262 sample rate is capable of high magnetic input frequencies, and is suitable to most applications. Contact your Allegro representative for more information regarding suitability to high frequency applications.

Inherent Quadrature

With the planar and vertical elements located in essentially the same spot, this sensing technique alleviates the need for ring magnet target optimization to achieve quadrature (90° phase separation between output channels).

Dual-planar sensor ICs will only have the two channels in quadrature when the ring magnet pole-pair pitch is 4× that of the Hall element pitch.

Figure 10 above shows a ring magnet with the magnet pole pitch dimension optimized for a dual-planar sensor IC, resulting in 90° phase separation in the output signals, while Figure 11 below shows a ring magnet with a significantly larger magnet pole pitch. This larger pole pitch is not optimized for the Hall element spacing of the dual-planar sensor IC, and results in a significantly smaller output signal phase separation. Since the 2D sensor IC is not affected by the magnet pole pitch, the output signals remain in quadrature (90° phase separation).

Figure 12 below illustrates how a 2D sensor array achieves quadrature sensing independent of the magnet dimensions.

1. 这IC is positioned over a south pole. In this position, the perpendicular flux is in the Z axis, and only passes through the planar Hall element, while there is no perpendicular flux in the X axis. Therefore the respective output channels will output a voltage proportional to the perpendicular flux. The Z channel will output a positive voltage, while the X channel will be at zero volts.
2. 这IC is positioned over the transition from south-to-north poles. Now the Z channel output will be zero and the X channel output will be a positive voltage.
3. 这IC is positioned over a north pole, resulting in the Z channel output to be negative, while the X channel is back to zero.
4. 这IC is positioned over the transition from north-to-south poles. The Z channel output is now zero again, while the X channel output is negative.

Phase Separation

Phase separation with the A1262 is inherently 90°, regardless of the magnet pole pitch. However, the mechanical placement can affect the phase separation.

As shown in Figure 13, when the sensor IC is not aligned with the axis of rotation (tangential offset), the phase separation can shift by several degrees from 90°. The amplitude of the shift in phase separation depends on the amount of mechanical offset. In this example, the effects are exaggerated due to the relatively large offset and a small diameter ring magnet.

总结和结论

A1262采用新的垂直霍尔传感技术，为旋转环磁体和电机应用提供理想的解决方案。亚博尊贵会员与现有的双通道霍尔锁存IC相比，使用A1262的设计更容易，但整个系统配置和机械包装的更具限制和更多选项。二维双通道磁传感器IC提供的前所未有的灵活性减轻了优化输出正交的环形磁体目标的需要，并且选择两个不同的垂直感测轴，为IC和PCB安装提供各种选项。

• 设计者可以选择四种不同的感测方向中的任何一种，以及在表面安装（LH）或通孔包（K）之间的选择。
• 2D sensing provides inherent output signal quadrature, irrespective of the ring magnet design, providing the option to use existing ring magnets from other applications or to select an off-the-shelf ring magnet.
• X-Z选项提供改进的Teag，包括在SOT包中提供的Teagucate Dualchannel设备。
• 使用表面安装装置感测平面内的平面的能力支持具有更少的装配步骤与传感器在通孔（SIP）封装中的传感器的较小较轻的系统的设计。

For additional information of theAllegro A1262 2D Hall-effect sensor IC，请参阅A1262 datasheet和其他应用注释s available in theyabo 11选5

yabo 11选5