A1102LLHLT - Unipolar Hall Effect Switch, 180G Trip, SOT-23W
料号： A1102LLHLT ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.18 | $21.80 |
| 100 | $1.84 | $184.00 |
| 500 | $1.52 | $760.00 |
| 1,000 | $1.29 | $1,290.00 |
| 3,000 | $1.05 | $3,150.00 |
A1102LLHLT 概述
A Hall-effect switch is a magnetic sensor whose output changes state when the applied magnetic flux density crosses a programmed threshold. Compared with reed switches, Hall ICs offer solid-state reliability, sub-microsecond response, and integration of the sensing element, signal conditioning, and output driver in a single silicon die. The A1102 belongs to Allegro's continuous-time family: the on-chip oscillator drives a dynamic-cancellation chopper-stabilized Hall plate, eliminating the residual offset of DC-biased Hall elements and yielding a stable switch point over temperature and supply.
Key features include a south-pole-only unipolar transfer function (output turns on when |B| exceeds Bop and off when |B| falls below Brp), 20 kHz typical chopping frequency for clean output, low quiescent current, 30 V absolute-maximum supply tolerance, and reverse-battery protection on the supply pin. The open-drain output requires an external pull-up resistor, simplifying interface to 3.3 V, 5 V, or 12 V logic rails without level shifting.
Architecturally, the device combines a BiCMOS Hall sensing front-end, a precision comparator with trimmed thresholds, an open-drain DMOS output stage, and on-chip protection (reverse-supply, over-voltage, and output ESD). The BiCMOS process enables fast power-on (<10 µs) and low-noise operation without the offset drift seen in older bipolar Hall ICs, while the chopper-stabilized front end virtually eliminates the residual offset that would otherwise shift the switch point with mechanical stress.
Typical applications include automotive seat-belt buckle detection, gear-shift and transmission position sensing, BLDC motor commutation triggers, valve and solenoid position feedback, consumer appliance lid/door interlocks, and contactless limit switches. The wide 3.8 V-24 V supply range allows direct connection to 12 V automotive rails without an upstream regulator.
Designers should provide a bypass capacitor of at least 0.1 µF close to the supply pin and a pull-up resistor (typically 10 kΩ) on the output. Place the device so the brand-side marking aligns with the target magnet's pole direction; the sensitive axis is perpendicular to the package top.
This page synthesizes distributor pricing, drop-in SOT-23W alternatives, and practical design notes that the manufacturer datasheet alone does not aggregate.
直接替换替代料： A1102LLHLT ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
A1101LLHLT
✅ 直接替换📋 参考替代料（不在目录中）
A1103LLHLT
✅ 直接替换📋 参考替代料（不在目录中）
A1104LLHLT
✅ 直接替换📋 参考替代料（不在目录中）
A1106LLHLT
✅ 直接替换📋 参考替代料（不在目录中）
A1102EUA
✅ 直接替换📋 参考替代料（不在目录中）
SS39ET
✅ 直接替换📋 参考替代料（不在目录中）
A1102LLHLT 最大额定值与电气特性
| 传感器类型 | Hall Effect Digital Switch |
| Switch Type | Unipolar (South Pole) |
| 输出类型 | Open Drain |
| Magnetic Trip Point (Bop, typ.) | 180 G (24.5 mT) |
| Magnetic Release Point (Brp, typ.) | 125 G (6 mT) |
| Supply Voltage Range | 3.8 V to 24 V |
| Absolute Maximum Supply Voltage | 30 V |
| 工作温度范围 | -40 °C to +150 °C (TA) |
| Output Current (sink) | 30 mA (max) |
| Power-On Time | < 10 µs |
| Chopping Frequency | 20 kHz (typ.) |
| 封装 | SOT-23W (3-pin) |
| 安装类型 | Surface Mount |
| Lead Finish | Matte Tin (Sn) |
| MSL 等级 | 1 |
| RoHS 状态 | Compliant |
| ESD Protection | Output ESD protected (per datasheet) |
| Reverse Battery Protection | Yes |
A1102LLHLT 引脚配置
| 引脚 1 | VCC — Supply voltage input, 3.8 V to 24 V |
| 引脚 2 | GND — Ground reference |
| 引脚 3 | OUTPUT — Open-drain Hall switch output; external pull-up required |
典型应用
A1102LLHLT 适用于 6 应用s: Automotive Seat-Belt Buckle Detection, Gear-Shift and Transmission Position Sensing, BLDC Motor Commutation Trigger, Valve and Solenoid Position Feedback, Consumer Appliance Lid/Door Interlock, Contactless Limit Switch Replacement.
Automotive Seat-Belt Buckle Detection
The A1102LLHLT's 180 G unipolar trip point and -40 °C to +150 °C automotive temperature range make it ideal for seat-belt buckle latching sensors. A small permanent magnet embedded in the buckle slides into proximity with the SOT-23W sensor when latched; the open-drain output drives low and signals the airbag controller that the buckle is fastened. The 30 V absolute-maximum supply tolerance withstands 12 V automotive load-dump transients without external TVS protection, and the chopper-stabilized front-end prevents switch-point drift over the 15-year vehicle service life. Designers typically place the sensor on a flexible tail of the buckle PCB with a 0.1 µF VCC bypass capacitor.
推荐
Gear-Shift and Transmission Position Sensing
The A1102LLHLT delivers a clean digital edge for PRNDL position feedback in automatic transmissions. Mounted on a small PCB near each detent, the sensor triggers when a magnet embedded in the shift lever enters the trip window. The 20 kHz chopping frequency eliminates output chatter during slow lever movement, and the 55 G hysteresis prevents false release at the exact threshold. The 3.8 V to 24 V supply range allows direct connection to the 12 V body control module without an LDO, reducing BOM cost and quiescent draw. The SOT-23W footprint fits inside space-constrained gear-shift assemblies.
推荐
BLDC Motor Commutation Trigger
The A1102LLHLT functions as a low-cost Hall-sensor for trapezoidal commutation in small BLDC motors, fans, and water pumps. Three sensors spaced 120 electrical degrees apart provide six-step commutation signals directly to a driver IC. The sub-10 µs power-on time allows the controller to start the motor within one electrical cycle after release from standby, and the 30 mA sink current is sufficient to drive opto-isolated or gate-driver inputs directly. For sinusoidal (FOC) commutation requiring linear feedback, upgrade to the Allegro A1302 or A3214 instead.
推荐
Valve and Solenoid Position Feedback
The A1102LLHLT provides end-of-travel position confirmation for pneumatic and hydraulic solenoid valves used in industrial process control. A magnet mounted on the spool triggers the sensor when the valve reaches full open or full close, allowing the controller to verify actuation without a mechanical limit switch. The solid-state Hall IC survives millions more cycles than reed switches in high-vibration solenoid environments, and the chopper-stabilized front-end rejects the 50/60 Hz electromagnetic interference common in industrial cabinets.
推荐
Consumer Appliance Lid/Door Interlock
The A1102LLHLT's small SOT-23W footprint fits inside washing-machine door latches and microwave oven interlocks where PCB area is constrained. A magnet in the door triggers the sensor when the door closes, and the controller refuses to start the motor until the open-drain output confirms latching. The 3.8 V minimum supply allows operation directly from a 5 V logic rail, while the open-drain output interfaces cleanly to a 3.3 V MCU GPIO without level shifting. The -40 °C to +150 °C range covers unheated garage and laundry-room installations.
推荐
Contactless Limit Switch Replacement
The A1102LLHLT replaces mechanical limit switches in factory automation where dust, oil, or mechanical wear would otherwise shorten contact life. A permanent magnet on the moving part triggers the Hall switch when in position, eliminating contact bounce and providing sub-millimeter repeatability. The wide 3.8 V to 24 V supply range accommodates both 24 V PLC inputs and 5 V logic controller inputs. Reverse-battery protection prevents damage during installation rework, and the 30 V absolute-maximum rating tolerates the inductive kickback typical of long cable runs in industrial cabinets.
推荐
推荐产品汇总
工程参考数据： A1102LLHLT ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | A1101LLHLT | A1103LLHLT | A1104LLHLT | A1106LLHLT | A1102EUA | SS39ET |
|---|---|---|---|---|---|---|---|
| Package | SOT-23W (3-pin) | SOT-23W (3-pin) - same | SOT-23W (3-pin) - same | SOT-23W (3-pin) - same | SOT-23W (3-pin) - same | SIP-3 (UA) - through-hole | SOT-23 (3-pin) - same footprint |
| Brand | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Honeywell |
| Magnetic Trip (Bop, typ.) | 180 G (24.5 mT) | 230 G | 130 G | 175 G | 180 G (inverted polarity) | 180 G | 150 G |
| Supply Voltage | 3.8 V to 24 V | 3.8 V to 24 V | 3.8 V to 24 V | 3.8 V to 24 V | 3.8 V to 24 V | 3.8 V to 24 V | 2.7 V to 24 V |
| Output Type | Open Drain | Open Drain | Open Drain | Open Drain | Open Drain | Open Drain | Open Collector |
| Operating Temperature | -40 °C to +150 °C | -40 °C to +150 °C | -40 °C to +150 °C | -40 °C to +150 °C | -40 °C to +150 °C | -40 °C to +150 °C | -40 °C to +150 °C |
| Unit Price (qty-1, USD, as of 2026-10-06) | 2.45 | approx. 2.45 (Allegro family) | approx. 2.45 (Allegro family) | approx. 2.45 (Allegro family) | approx. 2.45 (Allegro family) | approx. 1.95 (through-hole, lower) | approx. 2.80 (Honeywell) |
关键差异点
- Wide 3.8 V to 24 V supply supports direct 12 V automotive rails （对比 SS39ET (Honeywell))
- 180 G mid-range trip covers most magnet-air-gap combinations （对比 A1101LLHLT (230 G trip) and A1103LLHLT (130 G trip))
- Chopper-stabilized front-end eliminates switch-point drift over stress and temperature （对比 Older Allegro 312x/314x bipolar Hall switches)
设计说明
Place a 0.1 µF ceramic bypass capacitor within 5 mm of the VCC pin (Pin 1). For long VCC traces or noisy automotive environments, add a 10 µF bulk capacitor on the same node. Allegro's A110x application notes recommend keeping the bypass loop area under 25 mm² to minimize supply ringing at the 20 kHz chopping frequency.
The open-drain output (Pin 3) WILL NOT drive high without an external pull-up resistor. A 10 kΩ pull-up to VCC or to a 3.3 V/5 V logic rail is typical. Forgetting the pull-up is the single most common reason a Hall switch 'does not work' on the bench - the output simply floats at undefined voltage. If the pull-up is tied to a logic rail different from VCC, ensure the output's VOH does not exceed the sensor's absolute-maximum rating.
Estimated: at VCC = 24 V with open-drain output OFF (no current), quiescent dissipation is below 50 mW and the SOT-23W junction rises less than 5 °C above ambient. With output ON sinking 20 mA, dissipation adds 0.48 W at VCC = 24 V, but the SOT-23W theta_JA of ~250 °C/W on a small copper pour would push Tj above 150 °C. Derate sink current or increase copper pour for high-VCC continuous-on operation.
The Hall sensitive axis is perpendicular to the top face of the package. Position the SOT-23W so that the brand-side marking faces the incoming magnet's south pole - reversing the device 180° inverts the trip direction. For through-hole assemblies, the A1102EUA has the sensitive axis through the curved side of the SIP package per the Allegro datasheet.
合规信息
RoHS compliant per Allegro product page. Matte-Tin lead finish confirmed from datasheet. AEC-Q100 qualification documentation should be requested from Allegro for the specific date code used in production builds. Halogen-free status not explicitly stated in the verified data.
