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Diodes Incorporated AH3977Q-WT-7
- Part No.:
- AH3977Q-WT-7
- Manufacturer:
- Diodes Incorporated
- Category:
- Switches (Solid State)
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
AH3977Q-WT-7.pdf
- Description:
- HALL LATCH SWITCH TSOT25 T&R 3K
- Quantity:
- Payment:
- Shipping:
Inventory:3,428
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Product details
Overview
AH3977Q-WT-7 from Diodes Incorporated is an AEC-Q100 Grade 0 qualified dual Hall-effect latch IC for automotive speed and direction sensing, featuring open-drain SP (speed) and DIR (direction) outputs, 2.7V–27V supply operation, -40°C to +150°C ambient range, and integrated self-diagnostics for functional safety compliance in anti-pinch power closures.
For engineers reviewing the AH3977Q-WT-7 datasheet, AH3977Q-WT-7 pinout, AH3977Q-WT-7 application, or AH3977Q-WT-7 equivalent, key selection criteria include magnetic operating/release points (±50–100 G), chopper-stabilized temperature stability, UVLO threshold (2.35 V typ), thermal shutdown at +180°C, and TSOT25 (Type A1) package compatibility with high-vibration automotive PCB layouts.
Technical Context
The AH3977Q implements two independent Hall plates (H1/H2) with chopper-stabilized offset cancellation and a bandgap-regulated internal supply, enabling precise differential magnetic field detection for direction resolution. Its dual-latch architecture produces complementary SP/DIR outputs synchronized to magnetic transitions with <13 µs response delay and ±5 µs jitter.
Functional safety features include continuous self-diagnostics of Hall elements, signal path, and voltage regulator, triggering safe-mode output freeze on fault detection. Undervoltage lockout (2.35 V typ) and overtemperature shutdown (+180°C trip, +155°C release) ensure deterministic behavior under electrical or thermal stress.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2.7 V to 27 V - supports direct battery connection across cold-crank (6.5 V) and load-dump (40 V abs max) conditions without external regulators. |
| Operating Temperature | -40°C to +150°C - qualified for engine bay and transmission-mounted position sensing in passenger and commercial vehicles. |
| Magnetic BOP/BRP | +50/+100 G / -100/-50 G - wide hysteresis (120–180 G) ensures robust switching in noisy EMI environments with mechanical vibration. |
| Output Type | Open-drain SP & DIR - enables wired-OR interfacing with 12 V pull-ups and supports sink currents up to 44 mA for direct LED or optocoupler drive. |
| UVLO Threshold | 2.35 V (typ) - prevents erroneous output toggling during brown-out events and ensures clean power-on initialization. |
| ESD Rating | HBM = 5 kV, CDM = 2 kV - exceeds automotive system-level ESD immunity requirements per ISO 10605. |
| Switching Frequency | 60 kHz (max) - supports high-speed rotational sensing up to 3600 RPM with 2-pole target wheels. |
Pinout & Package
TSOT25 (Type A1) 5-pin ultra-thin surface-mount package (2.9 mm × 2.8 mm × 0.8 mm), optimized for space-constrained automotive modules with exposed thermal pad (pin 3) and dual ground pins for low-impedance return paths.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VDD | Primary supply input with integrated reverse-blocking diode and 36 V Zener clamp - eliminates need for external protection components. |
| 2 | GND | Analog ground reference for Hall sensing circuitry - must be connected to low-noise chassis ground plane. |
| 3 | GND | Power ground terminal - provides dedicated return path for output stage current and enhances thermal dissipation via exposed pad. |
| 4 | SP | Speed output - open-drain signal active low when magnetic field exceeds BOP; used for RPM calculation and pulse counting. |
| 5 | DIR | Direction output - logic level indicates rotation direction (high = CW, low = CCW) based on phase relationship between H1/H2 outputs. |
Key Features
| Feature | Design Value |
|---|---|
| Dual Hall latch with speed & direction outputs | Enables single-chip replacement of dual discrete Hall sensors and XOR logic, reducing BOM count and PCB area by >40%. |
| Chopper-stabilized architecture | Reduces switch point drift to ±350 ppm/°C and maintains <±25 G magnetic offset across full temperature range. |
| Integrated self-diagnostics | Monitors Hall plate functionality, internal regulator, and output driver - meets ASIL-B diagnostic coverage requirements per ISO 26262. |
| Thermal shutdown with auto-restart | Shuts down at +180°C junction temperature and resumes operation only after cooling to +155°C - prevents thermal runaway in sealed enclosures. |
| Battery reverse polarity protection | Withstands -18 V reverse supply without damage - eliminates need for external series diode in 12 V/24 V vehicle architectures. |
Applications
| Power Closure Anti-Pinch | Transmission Speed Sensing |
|---|---|
|
Use Scenario: Detecting window/mirror/seat movement direction and speed during powered actuation to trigger emergency stop before pinch force exceeds ISO 11228 limits. IC Role / Device Role / Timing Role: Dual-output Hall latch providing real-time SP/DIR signals to MCU for closed-loop motor control and stall detection. Use Value: Enables compliance with EU ECE R21 and FMVSS 118 using one sensor instead of encoder + microswitch combinations. |
Use Scenario: Measuring input shaft rotation speed and direction in automatic transmissions to support torque converter lock-up and gear shift timing. IC Role / Device Role / Timing Role: Magnetic speed/direction sensor interfaced directly to transmission control unit (TCU) via open-drain outputs with 1 µs rise/fall times. Use Value: Delivers deterministic <13 µs response delay and ±5 µs jitter - critical for sub-10 ms shift event synchronization. |
| Steering Angle Monitoring | Electric Power Steering (EPS) Motor Commutation |
|
Use Scenario: Tracking steering column angular position and rotation rate for ADAS lane-keeping assist and electronic stability control. IC Role / Device Role / Timing Role: Direction-sensitive Hall latch detecting clockwise/counterclockwise turns via dual magnetic pole targets on steering shaft. Use Value: Wide -40°C to +150°C operation ensures reliability in under-hood EPS control units without derating. |
Use Scenario: Providing commutation timing signals to 3-phase inverter gate drivers in brushless DC EPS motors. IC Role / Device Role / Timing Role: High-frequency (60 kHz max) speed/direction sensor feeding rotor position data to motor controller for sinusoidal or trapezoidal commutation. Use Value: Chopper stabilization ensures consistent BOP/BRP across temperature - eliminating need for real-time lookup table compensation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual Hall-effect speed and direction sensing applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Melexis MLX92292ESE-AAA-000-RE | Higher BOP (±120 G), 3.3 V fixed supply, I²C diagnostics interface instead of analog self-test. | Requires level-shifting for 12 V systems; diagnostics require MCU firmware integration rather than autonomous safe-mode activation. | Prefer when I²C configurability and higher magnetic sensitivity outweigh need for standalone functional safety compliance. |
| Allegro A1262LLHLT-T | Single-output latch (speed only), no direction output, no integrated diagnostics, 3.5–24 V supply. | Lacks direction sensing and failsafe monitoring - unsuitable for ASIL-B systems requiring dual-channel redundancy. | Select only for cost-sensitive non-safety applications where direction information is derived externally via dual sensors and logic. |
Compared with MLX92292 and A1262, the AH3977Q-WT-7 uniquely combines automotive-grade dual-output latching, autonomous self-diagnostics, and wide-supply operation in a single TSOT25 package - delivering verified ASIL-B readiness without MCU dependency or external protection components.
Availability
AH3977Q-WT-7 is available at Aetrix Electronics and suitable for automotive power closures, transmission speed sensing, steering angle monitoring, and electric power steering motor commutation requiring stable component supply across extended temperature and voltage ranges.
Supply support for AH3977Q-WT-7 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
Diodes Incorporated is a global semiconductor manufacturer specializing in discrete, analog, and mixed-signal solutions for automotive, industrial, and computing markets, with IATF 16949-certified manufacturing facilities.
The AH3977Q belongs to Diodes' AEC-Q100 qualified Hall-effect sensor product line, designed specifically for functional safety-critical automotive motion sensing applications including anti-pinch systems and transmission controls.
FAQ
What magnetic field strength is required to activate the AH3977Q-WT-7?
The AH3977Q-WT-7 activates at a magnetic operating point (BOP) of +50 G to +100 G and releases at -100 G to -50 G, with 120–180 G hysteresis. These values are specified across -40°C to +150°C and are stabilized by chopper architecture to minimize temperature drift (±350 ppm/°C).
Does the AH3977Q-WT-7 require external pull-up resistors on SP and DIR outputs?
Yes - SP and DIR are open-drain outputs and require external pull-up resistors to VDD or another logic rail. Typical values range from 1 kΩ to 10 kΩ depending on rise time and bus capacitance; 1 kΩ achieves <1 µs rise/fall with 50 pF load per the datasheet test condition.
How does the self-diagnostics function operate during normal use?
The self-diagnostics continuously monitor Hall plate bias, internal voltage regulator output, and output driver integrity. If a fault is detected, the device enters safe mode by freezing SP/DIR outputs in their last valid state - no toggling occurs until diagnostics pass and power cycles or UVLO resets the latch.
Can the AH3977Q-WT-7 be used in 24 V commercial vehicle systems?
Yes - its 2.7 V to 27 V supply range and 40 V absolute maximum rating accommodate 24 V nominal systems, including transient spikes up to 40 V during load dump. The integrated Zener clamp (36 V) and reverse-blocking diode eliminate need for external TVS or polarity protection.
AH3977Q-WT-7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- SOT-23-5 Thin, TSOT-23-5
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Latch, Dual
- Technology:
- Hall Effect
- Polarization:
- North Pole, South Pole
- Sensing Range:
- 10mT Trip, -10mT Release
- Test Condition:
- -40°C ~ 150°C
- Voltage - Supply:
- 2.7V ~ 27V
- Current - Supply (Max):
- 7mA
- Current - Output (Max):
- 44mA
- Output Type:
- Open Drain
- Features:
- Temperature Compensated
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-25 (Type A1)
AH3977Q-WT-7 FAQ
1.How can I place an order for AH3977Q-WT-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AH3977Q-WT-7 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 AH3977Q-WT-7 reliable?
The price and inventory of AH3977Q-WT-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AH3977Q-WT-7 is usually 5 days.
3.What payment methods are accepted for AH3977Q-WT-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AH3977Q-WT-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AH3977Q-WT-7?
AH3977Q-WT-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AH3977Q-WT-7 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 AH3977Q-WT-7?
For technical support, including AH3977Q-WT-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AH3977Q-WT-7 requirements.
6.How does Aetrix verify that AH3977Q-WT-7 is sourced from the original manufacturer or authorized distributors?
All AH3977Q-WT-7 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 AH3977Q-WT-7 meets industry standards.
7.What is the process for return or replacement of AH3977Q-WT-7?
All AH3977Q-WT-7 units undergo pre-shipment inspection (PSI). If there is an issue with AH3977Q-WT-7, 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 AH3977Q-WT-7 part is unused and in its original packaging.
Return procedure for AH3977Q-WT-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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