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Allegro MicroSystems A1321LLHLT-T
- Part No.:
- A1321LLHLT-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Linear, Compass (ICs)
- Package:
- SOT-23W
- Datasheet:
-
A1321LLHLT-T.pdf
- Description:
- SENSOR HALL EFFECT ANALOG SOT23W
- Quantity:
- Payment:
- Shipping:
Inventory:4,065
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Product details
Overview
A1321LLHLT-T from Allegro MicroSystems is a ratiometric linear Hall-effect sensor IC optimized for high-temperature operation in automotive and industrial position sensing. It delivers 5.000 mV/G sensitivity, operates from –40 °C to +150 °C, features rail-to-rail ratiometric output with 2.5 V quiescent voltage at 5 V supply, and uses dynamic offset cancellation for stable performance under thermal stress.
For engineers reviewing the A1321LLHLT-T datasheet, A1321LLHLT-T pinout, A1321LLHLT-T application, or A1321LLHLT-T equivalent, this page provides verified technical context, package mapping, real-world use cases, and validated alternative options for legacy design support and obsolescence mitigation.
Technical Context
The A1321LLHLT-T integrates a BiCMOS monolithic circuit with Hall element, high-gain amplifier, rail-to-rail output stage, and proprietary dynamic offset cancellation using a 150 kHz internal clock. Its architecture enables precise magnetic field measurement while rejecting mechanical stress and thermal drift effects.
It operates ratiometrically across 4.5–5.5 V supply, maintains ±1.5% ratiometry on both quiescent voltage and sensitivity, and achieves 30 kHz bandwidth with <40 mV peak-to-peak noise (A1321 variant) when bypassed with 0.1 μF capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Sensitivity | 5.000 mV/G typical - enables high-resolution analog magnetic field measurement with minimal signal conditioning |
| Operating Temperature | –40 °C to +150 °C - qualified for under-hood automotive and industrial motor control environments |
| Quiescent Output Voltage | 2.5 V ±75 mV at 5 V supply - ratiometric center point simplifies ADC reference alignment |
| Supply Voltage Range | 4.5–5.5 V - compatible with standard 5 V regulated rails and tolerant of minor line variation |
| Output Bandwidth | 30 kHz - supports fast-responding position feedback in rotating machinery and servo systems |
| Dynamic Offset Cancellation Clock | 150 kHz - suppresses low-frequency drift and improves long-term stability without external components |
| Noise (Peak-to-Peak) | 40 mV max - defines minimum detectable field change in noisy EMI environments |
Pinout & Package
Package: 3-pin SOT-23W (LH suffix), lead-free with 100% matte tin plating, footprint per Allegro drawing 802840.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 1) | Power supply input | Accepts 4.5–5.5 V; includes internal Zener clamp (6–8.3 V) for transient protection |
| VOUT (Pin 2) | Analog output | Rail-to-rail ratiometric voltage proportional to magnetic flux density; drives ≥4.7 kΩ load |
| GND (Pin 3) | Ground reference | Common return for supply and output; critical for noise immunity in high-EMI applications |
Key Features
| Feature | Design Value |
|---|---|
| Dynamic offset cancellation | 150 kHz clock eliminates thermal and mechanical drift, enabling stable zero-field output over temperature cycling |
| Ratiometric rail-to-rail output | Output scales with supply voltage - preserves accuracy without separate voltage references or calibration |
| High-temperature qualification | Validated for continuous operation up to +150 °C ambient - suitable for engine compartment and powertrain applications |
| BiCMOS monolithic integration | Hall element + amplifier + output stage on single die - minimizes parasitic coupling and improves signal integrity |
| Robust EMC protection | Integrated filtering and layout-optimized design - meets automotive-level radiated and conducted immunity requirements |
Applications
| Automotive Throttle Position Sensing | Industrial Motor Commutation |
|---|---|
Use Scenario: Monitoring angular position of throttle plate in gasoline engines under hood temperatures up to 150 °C. IC Role / Device Role / Timing Role: Analog magnetic field transducer converting rotary motion into ratiometric voltage for ECU ADC sampling. Use Value: 5.000 mV/G sensitivity and ±1.5% ratiometry ensure consistent pedal response mapping across full temperature range without recalibration. | Use Scenario: Detecting rotor position in brushless DC motors used in HVAC blowers and industrial pumps. IC Role / Device Role / Timing Role: High-bandwidth (30 kHz) linear sensor feeding closed-loop commutation logic in real time. Use Value: Dynamic offset cancellation maintains zero-point stability during rapid thermal transients caused by motor heating cycles. |
| Heavy-Duty Gear Position Detection | Hydraulic Valve Linear Displacement |
Use Scenario: Measuring gear engagement state in off-road vehicle transmissions exposed to vibration and wide thermal swings. IC Role / Device Role / Timing Role: Ratiometric analog output directly interfaced to microcontroller ADC with no external gain/offset adjustment. Use Value: Immunity to mechanical stress ensures reliable position reporting despite shock loads and mounting strain. | Use Scenario: Monitoring spool position in electro-hydraulic control valves operating in diesel generator sets. IC Role / Device Role / Timing Role: High-precision linear transducer providing analog feedback for PID-controlled valve actuation. Use Value: 2.5 V quiescent output centered at 50% VCC simplifies differential measurement and reduces common-mode error in noisy power systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar linear Hall-effect sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A1324LLHLX-T | Same LH package, same 5.000 mV/G sensitivity, but updated process with improved ΔSens(TAmax) stability (–5% to +5% vs –5% to +5% for A1321LLHLT-T); discontinued status lifted | Qualified for new designs; supports extended lifecycle and current Allegro support channels | Select for new designs requiring drop-in replacement with enhanced long-term availability and thermal stability data |
| ACS724LLCTR-5AB-T | Current sensor (not Hall voltage sensor); 5 A range, bidirectional, 100 mV/A output; SOIC-8 package; different functional domain | Used where current monitoring replaces position sensing - e.g., motor phase current feedback instead of rotor angle | Choose only if system architecture shifts from magnetic position to current-based commutation or fault detection |
Compared with A1321LLHLT-T, the A1324LLHLX-T offers identical sensitivity and package with documented production continuity and tighter high-temperature sensitivity drift specs, while the ACS724LLCTR-5AB-T serves a fundamentally different measurement function and requires PCB redesign.
Availability
A1321LLHLT-T is available at Aetrix Electronics and suitable for automotive throttle sensing, industrial motor commutation, heavy-duty gear position detection, and hydraulic valve displacement applications requiring stable component supply despite end-of-life status.
Supply support for A1321LLHLT-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensing and power ICs, specializing in automotive-grade analog and mixed-signal solutions.
The A132X family was developed specifically for high-temperature linear and rotary position sensing in harsh environments, emphasizing ratiometric stability, mechanical stress immunity, and integrated offset cancellation.
FAQ
What is the operating temperature range of the A1321LLHLT-T?
The A1321LLHLT-T is rated for ambient operation from –40 °C to +150 °C. This high-temperature capability is validated per its qualification in automotive under-hood and industrial motor applications. The device's internal dynamic offset cancellation and BiCMOS process enable stable quiescent output and sensitivity across this full range, with specified drift limits of ±10 G equivalent and ±1.5% ratiometry.
Is the A1321LLHLT-T still in production?
No, the A1321LLHLT-T is a discontinued product. Allegro MicroSystems declared it Not for New Design as of January 31, 2011, and samples are no longer available. However, Aetrix Electronics maintains limited legacy inventory and supports continuity for existing production programs through traceable sourcing and lifecycle coordination.
What is the pin configuration and package type of the A1321LLHLT-T?
The A1321LLHLT-T uses a 3-pin SOT-23W (LH) surface-mount package. Pin 1 is VCC, Pin 2 is VOUT, and Pin 3 is GND - matching the standard LH pinout shown in Allegro's A1321-DS Rev. 23. The package is lead-free with 100% matte tin plating and follows footprint dimensions in Allegro drawing 802840.
How does the ratiometric output of the A1321LLHLT-T benefit system design?
The A1321LLHLT-T's ratiometric output means both its quiescent voltage (2.5 V at 5 V supply) and sensitivity (5.000 mV/G) scale linearly with VCC. This eliminates the need for a separate precision voltage reference when interfacing with an ADC, since supply rail variations affect both the sensor output and ADC reference proportionally - preserving measurement accuracy without additional components or calibration.
What is the recommended bypass capacitor for the A1321LLHLT-T?
The A1321LLHLT-T requires a 0.1 μF ceramic bypass capacitor placed between VCC and GND, as specified in the Functional Block Diagram and Electrical Characteristics section of the datasheet. This capacitor stabilizes the internal regulator, reduces noise coupling, and ensures proper operation of the 150 kHz dynamic offset cancellation circuit - directly impacting output stability and peak-to-peak noise (≤40 mV).
A1321LLHLT-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- SOT-23W
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Technology:
- Hall Effect
- Axis:
- Single
- Output Type:
- Analog Voltage
- Sensing Range:
- -
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Supply (Max):
- 8mA
- Current - Output (Max):
- 10mA
- Resolution:
- -
- Bandwidth:
- 30kHz
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Features:
- Temperature Compensated
- Supplier Device Package:
- SOT-23W
- Mounting Type:
- Surface Mount
A1321LLHLT-T FAQ
1.How can I place an order for A1321LLHLT-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A1321LLHLT-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for A1321LLHLT-T reliable?
The price and inventory of A1321LLHLT-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A1321LLHLT-T is usually 5 days.
3.What payment methods are accepted for A1321LLHLT-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A1321LLHLT-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A1321LLHLT-T?
A1321LLHLT-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A1321LLHLT-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for A1321LLHLT-T?
For technical support, including A1321LLHLT-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A1321LLHLT-T requirements.
6.How does Aetrix verify that A1321LLHLT-T is sourced from the original manufacturer or authorized distributors?
All A1321LLHLT-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A1321LLHLT-T meets industry standards.
7.What is the process for return or replacement of A1321LLHLT-T?
All A1321LLHLT-T units undergo pre-shipment inspection (PSI). If there is an issue with A1321LLHLT-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The A1321LLHLT-T part is unused and in its original packaging.
Return procedure for A1321LLHLT-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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