The A3211 and A3212 integrated circuits are ultrasensitive, pole independent Hall-effect switches with latched digital output. These devices are especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palmtop computers. A 2.5 to 3.5 V operation and a unique clocking scheme reduce the average operating power requirements to less than 15 µW with a 2.75 V supply.
Unlike other Hall-effect switches, either a north or south pole of sufficient strength will turn the output on in the A3212, and in the absence of a magnetic field, the output is off. The A3211 provides an inverted output. The polarity independence and minimal power requirements allow these devices to easily replace reed switches for superior reliability and ease of manufacturing, while eliminating the requirement for signal conditioning.
Improved stability is made possible through chopper stabilization (dynamic offset cancellation), which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.
This device includes on a single silicon chip a Hall-voltage generator, small-signal amplifier, chopper stabilization, a latch, and a MOSFET output. Advanced CMOS processing is used to take advantage of low-voltage and low-power requirements, component matching, very low input-offset errors, and small component geometries.
Four package styles provide magnetically optimized solutions for most applications. Miniature low-profile surface-mount package types EH and EL (0.75 and 0.50 mm nominal height) are leadless, LH is a 3-pin low-profile SMD, and UA is a three-pin SIP for through-hole mounting. Packages are lead (Pb) free (suffix, –T) with 100% matte tin plated leadframes
A3211 和 A3212 集成电路是带有锁存数字输出的超灵敏、不受磁极约束的霍尔效应开关。这些器件尤其适用于电池供电、手持型设备的操作，例如移动和无绳电话、传呼机以及掌上型电脑。2.5 至 3.5 V工作电压范围和独特的时钟方法，能将平均操作功率要求降低到 15 µW 以下（2.75 V 电源电压时） 。
与其他霍尔效应开关不同的是，只要北极或南极磁场强度足够大，就能打开 A3212 中的输出，没有磁场的时候，输出就会停止。A3211 提供反向输出。不受磁极影响和最低的功率要求，允许这些器件轻松取换簧片开关，具有更高的可靠性并便于制造，从而降低对信号条件的要求。
稳定斩波（动态偏移取消）提升了稳定性，可降低通常由器件超模压、温度依存性及热应力引起的剩余偏移电压。
该器件将霍尔发电机、小型信号放大器、稳定斩波特性、锁存和 MOSFET 输出集中在单硅片上。运用先进的 BiCMOS 工艺，实现低电压和低功率要求、元件匹配、极低的输入偏差错误和小型元件几何尺寸。
四种封装类型能为大多数应用提供磁性优化的解决方案。微型低厚度表面安装封装类型 EH 和 EL（标高为 0.75 和 0.50 mm）不含铅，LH 是三引脚低厚度 SMD，而 UA 则是用于过孔安装的三引脚 SIP。该封装为无铅封装（后缀 –T），引脚框采用 100% 雾锡电镀
